# Plasma p-tau181 as an outcome and predictor of multidomain intervention effects: a secondary analysis of a randomised, controlled, dementia prevention trial

Nicola Coley, Henrik Zetterberg, Christelle Cantet, Sophie Guyonnet, Nicholas

J Ashton, Bruno Vellas, Kaj Blennow, Sandrine Andrieu, Jean-François

Dartigues, Fleur Delva, et al.

► To cite this version:

Nicola Coley, Henrik Zetterberg, Christelle Cantet, Sophie Guyonnet, Nicholas J Ashton, et al. Plasma p-tau181 as an outcome and predictor of multidomain intervention effects: a secondary analysis of a randomised, controlled, dementia prevention trial. The Lancet. Healthy longevity, 2024, 5 (2), pp.e120-e130. hal-04959492

HAL Id: hal-04959492

https://hal.science/hal-04959492v1

Submitted on 20 Feb 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>
# Plasma p-tau181 as an outcome and predictor of multidomain intervention effects: a secondary analysis of a randomised, controlled, dementia prevention trial

Nicola Coley, Henrik Zetterberg, Christelle Cantet, Sophie Guyonnet, Nicholas J Ashton, Bruno Vellas, Kaj Blennow, Sandrine Andrieu for the MAPT study group*

<figure><img src="image_2.png" /></figure>

<figure><img src="image_3.png" /></figure>

CrossMark

<figure><img src="image_4.png" /></figure>

## Summary

**Background** It is unknown whether multidomain interventions, which might preserve late-life cognition, affect Alzheimer's disease pathology. Previous studies measured cerebrospinal fluid and imaging Alzheimer's disease biomarkers in small subsamples of multidomain trial participants. Newly developed assays enable the measurement of blood-based Alzheimer's disease biomarkers in larger samples. We aimed to assess whether plasma tau phosphorylated at threonine 181 (p-tau181) was able to detect or predict 3-year multidomain intervention effects.

**Methods** This is a secondary analysis of the randomised, controlled, Multidomain Alzheimer Prevention Trial (MAPT) testing a 3-year multidomain intervention, omega-3 fatty acid supplementation, or both versus placebo, in individuals aged 70 years and older in 13 memory centres in France and Monaco. Plasma p-tau181 was measured in stored blood samples in a subsample of 527 participants on an intention-to-treat basis. Changes in cognitive score were calculated as a composite measure using the average of Z scores for the following tests: Mini Mental State Examination orientation items, Free and Cued Selective Reminding Test (sum of free and total recall scores), category fluency, and Digit Symbol Substitution Test. Intervention effects on 3-year change in p-tau181 concentration were estimated by use of a linear mixed model with centre-specific random intercepts.

**Findings** Recruitment took place between May 30, 2008, and Feb 24, 2011. Median baseline plasma p-tau181 was 8.8 pg/mL (IQR 6.7–11.9) in the total sample, and significantly higher in older individuals, men, APOE ε4 carriers, and participants with renal dysfunction or a positive PET amyloid scan. During 3-year follow-up, individuals with raised baseline p-tau181 underwent greater cognitive decline (eg, mean difference in 3-year change on the composite cognitive score between control group participants with normal and abnormal baseline levels of p-tau was −0.34 [effect size −0.52; 95% CI −0.61 to 0.07] in the fully adjusted model using a 12.4 pg/mL cutoff for abnormal baseline p-tau181), but there were no intervention effects on change in p-tau181 either in this subgroup or the total population, and no effect on cognitive change in individuals with raised baseline p-tau181 (eg, in the fully adjusted model using the 12.4 pg/mL cutoff for p-tau181 abnormality, the mean difference [95% CI] in this subgroup in 3-year decline on the composite cognitive score between the control group and the multidomain + omega-3 group, the omega-3 group, and the multidomain intervention group, was, respectively: 0.13 [−0.21 to 0.47], 0.03 [−0.30 to 0.36], and 0.10 [−0.26 to 0.46]). Surprisingly, individuals with raised baseline p-tau181 showed a decrease in p-tau181 during follow-up (eg, unadjusted mean [95% CI] 3-year change was −3.01 pg/mL (−4.45 to −1.56) in control group subjects with abnormal baseline p-tau181 [using the 12.4 pg/mL abnormal p-tau cutoff]).

**Interpretation** Our results support the utility of p-tau181 as a prognostic biomarker, but it did not predict or detect intervention effects in this study. Further investigation of its usefulness as a prevention trial outcome measure is required.

**Funding** Toulouse Gérontopôle, French Ministry of Health and Pierre Fabre Research Institute.

**Copyright** © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.

## Introduction

Dementia is an increasingly common age-related disease, and modifiable risk factors might account for 40% of cases.¹ Multidomain interventions, targeting multiple risk factors simultaneously, could help prevent Alzheimer's disease and other forms of dementia, and some such interventions have shown beneficial effects on cognitive function in randomised controlled trials,

especially in at-risk populations.² However, their effects on the underlying pathology of Alzheimer's disease have not been well studied.³ In the Multidomain Alzheimer Prevention Trial (MAPT), for example, amyloid was quantified by PET in a subsample of 269 participants, and was found to be significantly lower in the groups randomised to multidomain lifestyle intervention, compared with placebo.⁴ Furthermore,

Lancet Healthy Longev 2024; 5: e120–30

See Comment page e88

*Members of the MAPT study group are listed at the end of the Article

Centre for Epidemiology and Research in Population Health, INSERM-University of Toulouse, UPS, Toulouse, France (N Coley PhD, C Cantet MSc, S Guyonnet PhD, Prof B Vellas MD PhD, Prof S Andrieu MD PhD);

Department of Epidemiology and Public Health, Toulouse University Hospital, Toulouse, France (N Coley, Prof S Andrieu); Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden

(Prof H Zetterberg MD PhD, N J Ashton PhD, Prof K Blennow MD PhD);

Clinical Neurochemistry Laboratory, Sahlgrenska

University Hospital, Mölndal,

Sweden (Prof H Zetterberg,

Prof K Blennow); Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK (Prof H Zetterberg); UK

Dementia Research Institute at UCL, London, UK

(Prof H Zetterberg); Hong Kong Centre for Neurodegenerative Diseases, Clear Water Bay, Hong Kong Special Administrative Region, China

(Prof H Zetterberg); Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA (Prof H Zetterberg); Gérontopôle of Toulouse, Institute of Ageing, Toulouse University Hospital, Toulouse, France (C Cantet, S Guyonnet, Prof B Vellas); Institute of Psychiatry, Psychology and Neuroscience King's College
London, London, UK
(N J Ashton); NIHR Biomedical
Research Centre for Mental
Health and Biomedical
Research Unit for Dementia at
South London and Maudsley
NHS Foundation, London, UK
(N J Ashton); Centre for Age-
Related Medicine, Stavanger
University Hospital, Stavanger,
Norway (N J Ashton)

Correspondence to:
Dr Nicola Coley, Centre for
Epidemiology and Research in
Population Health, Faculté de
Médecine, 31000 Toulouse,
France

nicola.coley@inserm.fr

Research in context

Evidence before this study

We searched PubMed up to Aug 1, 2023, using the terms "(biomarker OR amyloid OR tau) AND multidomain AND trial". The few studies assessing the effect of a multidomain intervention on longitudinal changes in the underlying pathology of Alzheimer's disease have involved small samples (n<150) and have only assessed structural or functional imaging biomarkers as outcomes. Possible intervention effects were observed on certain diffusion tensor imaging white matter markers, but not on other MRI markers or [¹⁸F] fluorodeoxyglucose-PET-measured brain metabolism.

Added value of this study

To our knowledge, this is the largest study to date assessing the
longitudinal effect of a multidomain intervention on an

Alzheimer's disease biomarker in a prevention trial setting, and the first such study to use a tau biomarker or a blood-based biomarker as an outcome measure. It is also the first study assessing multidomain intervention effects on cognitive decline in individuals with abnormal baseline tau concentrations.

Implications of all the available evidence

There is, so far, little evidence that multidomain interventions affect the underlying pathology of Alzheimer's disease, but further research is needed. Plasma tau phosphorylated at threonine 181 appears useful as a prognostic biomarker, in terms of predicting cognitive decline, but its utility as a prevention trial outcome measure has not yet been shown and requires further evaluation.

although in the primary analysis there were no
intervention effects on cognitive decline in this trial,
among the subsample that underwent PET imaging,
there was significantly less 3-year cognitive decline in
amyloid-positive participants who received the
multidomain intervention, compared with amyloid-
positive placebo participants, and there were no
between-group differences among amyloid-negative
participants.⁵,⁶ However, the cross-sectional nature of
the PET amyloid measurements, and the fact that they
were not all done at the same timepoint during the trial,
limits interpretation of these results. In terms of other
imaging markers, a small MAPT substudy suggested no
effect of multidomain intervention after 1 year on [¹⁸F]
fluorodeoxyglucose ([¹⁸F]FDG-PET-measured brain
metabolism,⁷ and small exploratory substudies of the
FINGER trial suggested a possible beneficial effect of a
2-year multidomain lifestyle intervention on certain
diffusion tensor imaging white matter markers,⁸ but not
on other MRI markers.⁹

Therefore, further exploration of the effects of
multidomain interventions on longitudinal changes in
markers of Alzheimer's disease pathology, and in
individuals with evidence of such pathology, is required.

Previously, expensive or burdensome procedures were
required to measure Alzheimer's disease biomarkers,
but reliable assays enabling their measurement in blood
samples have been developed.¹⁰ Plasma phosphorylated
tau markers, including phosphorylated tau at threonine
181 (p-tau181), correlate strongly with cerebrospinal
fluid, PET, and post-mortem brain tissue measures of
both amyloid and tau pathology at various clinical stages
of Alzheimer's disease, and can differentiate Alzheimer's
disease from other neurodegenerative disorders.¹¹⁻¹³
Because fluid markers of p-tau, unlike tau imaging
markers, are elevated in amyloid-positive cognitively
unimpaired individuals, and therefore might better
detect early Alzheimer's disease-related pathological

changes, they could be preferential for monitoring
intervention effects in prevention trials.¹³ Although
cerebrospinal fluid p-tau might be a closer indicator of
brain processes than peripheral measures,¹³ plasma
biomarkers offer huge advantages in clinical trial
settings, in terms of cost and burden, thus enabling
their measurement in larger numbers of participants.

Plasma p-tau181 detects treatment effects of anti-
amyloid therapies in early clinical Alzheimer's disease,¹⁴,¹⁵
but, to our knowledge, has not yet been evaluated in a
multidomain prevention trial setting. The primary aims
of this analysis were, therefore, first to assess the effects
of a multidomain intervention, omega-3 supplement-
ation, and both interventions combined on 3-year
change in plasma p-tau181, and second to assess
intervention effects on 3-year change in cognitive
performance and p-tau181 in participants with abnormal
baseline p-tau181.

Methods

Study design and participants

Recruitment took place between May 30, 2008, and
Feb 24, 2011, in 13 memory centres in France and
Monaco. This was a secondary analysis of the MAPT
trial, of which full details have been published
previously.⁶ Briefly, MAPT was a 3-year randomised
controlled trial evaluating the efficacy of a multidomain
lifestyle intervention (group-based cognitive training,
advice and education on physical activity and nutrition,
and an annual preventive consultation), omega-3 fatty
acid supplementation (800 mg docosahexaenoic acid
and 225 mg eicosapentaenoic acid daily), or both
interventions combined, compared with placebo, for the
prevention of cognitive decline. Participants were
1680 community-dwellers aged 70 years and older with
at least one of the following criteria: subjective memory
complaints, a limitation in one instrumental activity of
daily living,¹⁶ or slow walking speed (≤0·8 m/s). These
criteria were selected to identify individuals in the early stages of cognitive or physical frailty, or both, thought to be at increased risk of cognitive decline or dementia.¹⁷ At baseline, they had a Mini Mental State Examination score ≥24, no difficulties in basic activities of daily living,¹⁸ and were free of dementia. The present analysis included a subsample of participants (n=527) with plasma p-tau181 data, including 505 with measures at both baseline and 3 years. Due to French regulations we were unable to collect data on race or ethnicity.

The study was approved by the Toulouse Ethics Committee and the French Health Authority, and all participants provided written informed consent.¹⁹

## Procedures

Cognitive function was measured at baseline, and 6, 12, 24, and 36 months of follow-up. Plasma p-tau181 concentrations were measured in blood samples taken at baseline and 3 years and stored in edetic acid tubes at -80°C. Samples were analysed in 2022 at the Clinical Neurochemistry Laboratory, University of Gothenburg (Mölndal, Sweden), by use of an in-house Single molecule array (Simoa) method based on the AT270 (specific for the threonine-181 phosphorylation site), and Tau12 (N-terminal epitope 6-18 on human tau protein) anti-tau antibodies, as detailed previously.¹² All measurements were done by use of an HD-X Analyser (Quanterix, Billerica, MA, USA) in a single batch analysis. Samples from the same participants (baseline and follow-up) were analysed in parallel by board-certified laboratory technicians masked to clinical information and randomisation group. Values more than 3 SD above the mean and less than 1 pg/mL were excluded from this analysis.

PET amyloid scans were done in a subsample of participants at five sites at a single timepoint, either at baseline or during follow-up (mean [SD] time from baseline to PET acquisition: 512.7 [249.6] days). Regional ¹⁸F-florbetapir standardised uptake volume ratios were obtained via semi-automated quantitative analysis, by use of the cerebellum as the reference region, as described previously.²⁰ Participants with a standardised uptake volume ratio of at least 1.17 were considered amyloid-positive.²¹

Baseline sociodemographics and the following baseline clinical and biological measures were also used in this analysis: cognitive function (Mini Mental Status Examination), functional status (Alzheimer's Disease Cooperative Study—Activities of Daily Living Prevention Instrument), global status (Clinical Dementia Rating), depressive symptoms (15-item Geriatric Depression Scale), physical performance (Short Physical Performance Battery), estimated glomerular filtration rate (eGFR; values <60 were considered to indicate renal dysfunction),²² BMI, systolic and diastolic blood pressure, self-reported history of stroke or myocardial infarction, and APOE genotype (appendix p 1).

## Outcomes

The trial's primary outcome measure was 3-year change in a composite cognitive score calculated as the average of Z scores for the following tests: Mini Mental State Examination orientation items, Free and Cued Selective Reminding Test (sum of free and total recall scores), category fluency, and Digit Symbol Substitution Test. For the present analysis, the composite score was generated by calculating Z scores for each of the cognitive tests by use of baseline means and SDs from the p-tau181 subsample, and then the sum of the four Z scores was averaged. A Z score of -1, for example, represents a score that is 1 SD below the baseline mean, and a one-point decrease on the composite score indicates an average decline of 1 SD across the four cognitive tests.⁶

## Statistical analysis

Baseline characteristics are presented as mean (SD) or median (IQR) for continuous variables and frequency (%) for categorical variables. Formal power calculations were not done. Between-group comparisons of baseline characteristics were done by use of independent *t* tests (for two-group comparisons of normally distributed variables), one-way ANOVA (for ≥three-group comparisons of normally distributed variables), Wilcoxon rank-sum (for two-group comparisons of non-normally distributed variables) or Kruskal-Wallis (for ≥3-group comparisons of non-normally distributed variables) tests for continuous variables, and χ² or Fisher's exact (if expected values were <5) tests for categorical variables.

Intervention effects on 3-year change in p-tau181 concentration were estimated by use of a linear mixed model with centre-specific random intercepts. The random effects were assumed to have a normal distribution. Model residuals were assessed graphically in order to verify normality and homogeneity of variance. Models were run unadjusted, and with adjustment for baseline p-tau181 and the following prognostic variables: age, sex, and eGFR; and age, sex, eGFR, and APOE genotype. Models were first run for the whole sample, and then intervention effects were compared between subgroups with normal and raised baseline p-tau181 by introducing a group*baseline p-tau (dichotomised as normal–abnormal) interaction term. Since there are no established thresholds for abnormal p-tau181 concentrations, and cutpoints are likely to vary by assay and study population,²³ we used three methods to define abnormal baseline p-tau181 values in our population. First, we considered the highest tertile of the baseline distribution as abnormal, and for the second and third methods, we used receiver operating curves and the Youden index to identify optimal p-tau181 cutpoints for discriminating between individuals with and without a positive PET amyloid scan (amongst the subsample with an amyloid PET scan) and a diagnosis of Alzheimer's dementia during 3-year follow-up. Alzheimer's dementia was diagnosed by study investigators on the basis of clinical criteria, as per standard practice in each of the

See Online for appendix
participating memory centres (Diagnostic and Statistical Manual of Mental Disorders-IV and National Institute of Neurological Disorders and Stroke-Alzheimer Disease and Related Disorders criteria were used at the time of the study). Dementia diagnoses and probable causes were reviewed first by an internal study committee, and then by an independent external committee, both of which had access to the participants' cognitive evaluations. Participants who were diagnosed with non-Alzheimer's disease forms of dementia were excluded from the receiver operating characteristic curve analysis. The percentage of PET positive and negative participants diagnosed with dementia during follow-up is shown in the appendix (p 2).

Intervention effects on 3-year change in the composite cognitive score according to baseline p-tau181 status were estimated by use of longitudinal linear mixed models

with random subject intercepts and random quadratic slopes (which were retained in the model following verification by use of the restricted maximum likelihood procedure and were assumed to have a normal distribution). Model residuals were assessed graphically in order to verify normality and homogeneity of variance. In the unadjusted models, fixed effects were time, time², a group*p-tau181 interaction term, and interactions between this term and time and time². Models were then adjusted for gender, age, eGFR, and their interactions with time; and the same adjustment variables, plus APOE genotype and its interaction with time.

Analyses were done on an intention-to-treat basis, by use of Stata version 18.0 and SAS version 9.4. p values for the estimation of intervention effects were adjusted for multiple comparisons by use of the Hochberg procedure.

<table><thead><tr><th></th><th>Total sample (n=505)</th><th>Multidomain intervention plus omega-3 (n=132)</th><th>Omega-3 (n=121)</th><th>Multidomain intervention (n=119)</th><th>Control (n=133)</th><th>p value</th></tr></thead><tbody><tr><td>Age, years</td><td>74 (72-78)</td><td>74 (71-78)</td><td>75 (72-78)</td><td>74 (71-78)</td><td>74 (71-77)</td><td>0.33</td></tr><tr><td>Sex</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Female</td><td>340 (67%)</td><td>91 (69%)</td><td>79 (65%)</td><td>80 (67%)</td><td>90 (68%)</td><td>..</td></tr><tr><td>Male</td><td>165 (33%)</td><td>41 (31%)</td><td>42 (35%)</td><td>39 (33%)</td><td>43 (32%)</td><td>0.94</td></tr><tr><td>Level of education*</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Low</td><td>13/499 (2.6%)</td><td>3/131 (2%)</td><td>3/120 (3%)</td><td>3/117 (3%)</td><td>4/131 (3%)</td><td>0.44</td></tr><tr><td>Medium</td><td>268/499 (53.7%)</td><td>79/131 (60%)</td><td>69/120 (58%)</td><td>57/117 (49%)</td><td>63/131 (48%)</td><td>..</td></tr><tr><td>High</td><td>218/499 (44%)</td><td>49/131 (37%)</td><td>48/120 (40%)</td><td>57/117 (49%)</td><td>64/131 (49%)</td><td>..</td></tr><tr><td>Mini Mental State Examination</td><td>28 (27-29)</td><td>28 (27-29)</td><td>28 (27-29)</td><td>29 (27-29)</td><td>29 (27-30)</td><td>0.28</td></tr><tr><td>Eligibility criteria</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Memory complaint</td><td>502 (99%)</td><td>132 (100%)</td><td>121 (100%)</td><td>117 (98%)</td><td>132 (99%)</td><td>0.19</td></tr><tr><td>Instrumental Activities of Daily Living limitation</td><td>46 (9%)</td><td>8 (6%)</td><td>17 (14%)</td><td>12 (10%)</td><td>9 (7%)</td><td>0.11</td></tr><tr><td>Slow walking speed</td><td>53/504 (11%)</td><td>11/131 (8%)</td><td>12 (10%)</td><td>12 (10%)</td><td>18 (14%)</td><td>0.58</td></tr><tr><td>Clinical Dementia Rating</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>0</td><td>305 (60%)</td><td>79 (60%)</td><td>69 (57%)</td><td>73 (61%)</td><td>84 (63%)</td><td>0.79</td></tr><tr><td>0.5</td><td>200 (40%)</td><td>53 (40%)</td><td>52 (43%)</td><td>46 (39%)</td><td>49 (37%)</td><td>..</td></tr><tr><td>Geriatric Depression Scale</td><td>3 (1-4)†</td><td>3 (1-4)</td><td>3 (1-5)‡</td><td>3 (2-5)§</td><td>2 (1-4)</td><td>0.21</td></tr><tr><td>Short Physical Performance Battery</td><td>11 (10-12)†</td><td>11 (10-12)¶</td><td>11 (10-12)‡</td><td>11 (10-12)</td><td>11 (10-12)||</td><td>0.28</td></tr><tr><td>Alzheimer's Disease Cooperative Study—Activities of Daily Living</td><td>41 (38-44)†</td><td>41 (38-43)¶</td><td>41 (38-44)</td><td>41 (37-43)</td><td>42 (39-44)||</td><td>0.60</td></tr><tr><td>Estimated glomerular filtration rate, mL/min per 1.73 m²</td><td>76-1 (64.2-86.2)†</td><td>79-1 (64.1-86.3)¶</td><td>75-9 (65.8-86.7)‡</td><td>75-1 (65.0-84.8)§</td><td>73-4 (61.9-86.3)||</td><td>0.90</td></tr><tr><td>BMI, kg/m²</td><td>26-2 (4.0)†</td><td>26-3 (4.0)</td><td>26-4 (3.9)</td><td>26-1 (4.2)</td><td>26-1 (3.9)||</td><td>0.88</td></tr><tr><td>Systolic blood pressure, mm Hg</td><td>139-9 (19.5)†</td><td>140-9 (20.2)¶</td><td>139-7 (20.5)</td><td>139-6 (17.0)</td><td>139-6 (20.2)</td><td>0.94</td></tr><tr><td>Diastolic blood pressure, mm Hg</td><td>79-3 (11.6)†</td><td>80-6 (12.5)</td><td>77-9 (11.7)</td><td>78-1 (10.3)</td><td>80-2 (11.6)</td><td>0.11</td></tr><tr><td>History of stroke</td><td>30/505 (6%)</td><td>11 (8%)</td><td>7 (6%)</td><td>7 (6%)</td><td>5 (4%)</td><td>0.48</td></tr><tr><td>History of myocardial infarction</td><td>11/505 (2%)</td><td>3 (2%)</td><td>3 (2%)</td><td>0</td><td>5 (4%)</td><td>0.23</td></tr><tr><td>APOE ε4 carrier</td><td>102/454 (22%)</td><td>23/118 (19%)</td><td>19/105 (18%)</td><td>30/107 (28%)</td><td>30/124 (24%)</td><td>0.28</td></tr><tr><td>PET amyloid-positive</td><td>56/138 (41%)</td><td>11/39 (28%)</td><td>12/31 (39%)</td><td>12/27 (44%)</td><td>21/41 (51%)</td><td>0.20</td></tr><tr><td>p-tau181, pg/mL</td><td>8-8 (6.7-11.9)</td><td>8-8 (6.6-11.9)</td><td>9-4 (6.9-11.9)</td><td>8-3 (6.7-11.2)</td><td>8-9 (7.1-12.1)</td><td>0.65</td></tr></tbody></table>

Data are median (IQR), n (%), or mean (SD). p-tau181=plasma tau phosphorylated at threonine 181. *Low education=primary school certificate or lower; intermediate education=middle-vocational school; high education=high school diploma (baccalaureate) or higher. †Denominator differs from column total for non-percentage data (n=418-504). ‡Denominator differs from column total for non-percentage data (n=101-120). §Denominator differs from column total for non-percentage data (n=97-118). ¶Denominator differs from column total for non-percentage data (n=111-131). ||Denominator differs from column total for non-percentage data (n=109-132).

<caption>Table 1: Baseline characteristics of Multidomain Alzheimer Preventive Trial participants included in the p-tau181 subsample</caption>
The MAPT trial is registered at [ClinicalTrials.gov](http://ClinicalTrials.gov), NCT00672685.

## Role of the funding source

The study funders had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

## Results

527 participants were selected for the p-tau181 analysis with 505 participants with both baseline and 3-year data (appendix p 11). The median (IQR) age was 74 years (72–78), two-thirds of 505 participants were female, 200 (40%) had a Clinical Dementia Rating score of 0·5, 218 of 499 (44%) had a high level of education (ie, high school diploma or higher), 102 of 454 (22%) were APOE ε4 carriers, and the median Mini Mental State Examination score was 28 (27–29). In terms of eligibility criteria, almost all participants (502 of 505, 99%) reported a subjective memory complaint, whereas only around 10% had an instrumental activity of daily living limitation or slow

walking speed (table 1). Among the subsample with a PET amyloid scan (n=138), 41% (n=56) were amyloid-positive. Within the p-tau sample, baseline characteristics were similar across the four randomisation groups. However, compared with participants excluded from this analysis, those who were included had fewer depressive symptoms, better physical and functional status, better kidney function, and a higher level of education (appendix p 3).

The median (IQR) baseline plasma p-tau181 concentration was 8·8 pg/mL (6·7–11·9) in the total sample, and was higher in older individuals (70–74 years 8·29 [6·21–11·20], 75–79 years 9·01 [6·95–12·50], 80–84 years 10·05 [7·89–13·00], ≥85 years 11·55 [10·40–21·90]; p=0·0001), men (10·00 pg/mL [7·46–12·60] vs 8·39 pg/mL [6·53–11·50] in women; p=0·0013), APOE ε4 carriers (9·76 pg/mL [7·53–12·50] vs 8·38 pg/mL [6·61–11·80] in non-carriers; p=0·039), and participants with renal dysfunction (10·10 pg/mL [7·39–12·80] vs 8·63 pg/mL [6·55–11·60] in those without dysfunction; p=0·038) or a positive PET amyloid scan (11·00 pg/mL [7·72–13·00] vs 7·89 pg/mL

<figure><img src="image_5.png" /><figcaption>**Figure:** Box plots of baseline p-tau181 distributions across subgroups</figcaption></figure>

p values indicate the results of nonparametric Kruskal-Wallis tests comparing between-group p-tau181 values. Circles indicate outliers (ie, values ≥1.5 × IQR above the upper quartile or below the lower quartile). p-tau181=plasma tau phosphorylated at threonine 181.
<table><thead><tr><th></th><th>Multidomain intervention plus omega-3 (n=132)</th><th>Omega-3 (n=121)</th><th>Multidomain intervention (n=119)</th><th>Control (n=133)</th></tr></thead><tbody><tr><td>Observed mean change from baseline</td><td>0.08<br>(-0.49 to 0.66)</td><td>0.27<br>(-0.44 to 0.98)</td><td>0.52<br>(-0.22 to 1.27)</td><td>-0.48<br>(-1.16 to 0.19)</td></tr><tr><td>Estimated unadjusted mean difference (95% CI) in change from baseline compared to control group</td><td>0.69<br>(-0.19 to 1.56)</td><td>0.83<br>(-0.07 to 1.72)</td><td>1.04<br>(0.13 to 1.94)</td><td>NA</td></tr><tr><td>p value*</td><td>0.13</td><td>0.11</td><td>0.075</td><td>..</td></tr><tr><td>Estimated mean difference (95% CI) in change from baseline compared to control group, adjusted for baseline p-tau, age, gender, and kidney function</td><td>0.63<br>(-0.23 to 1.49)</td><td>0.64<br>(-0.24 to 1.52)</td><td>0.89<br>(0.00 to 1.78)</td><td>NA</td></tr><tr><td>p value*</td><td>0.15</td><td>0.15</td><td>0.15</td><td>..</td></tr><tr><td>Estimated mean difference (95% CI) in change from baseline compared to control group, adjusted for baseline p-tau, age, gender, kidney function, and APOE genotype</td><td>0.65<br>(-0.21 to 1.51)</td><td>0.67<br>(-0.21 to 1.55)</td><td>0.91<br>(0.02 to 1.80)</td><td>NA</td></tr><tr><td>p value*</td><td>0.14</td><td>0.14</td><td>0.14</td><td>..</td></tr></tbody><tfoot><tr><td colspan="5">p-tau181=plasma tau phosphorylated at threonine 181. NA=not applicable. *Mean differences are estimated from a linear mixed model, and p values are adjusted for multiple comparisons using the Hochberg procedure.</td></tr></tfoot></table>

(5.97-10.90) in participants with a negative scan; p=0.0004; figure). However, there was little evidence of differences in plasma p-tau181 by level of education, BMI, history of stroke or myocardial infarction, Clinical Dementia Rating status, or the presence of an instrumental activity of daily living limitation or slow walking speed.

The cutoffs used to define abnormal baseline p-tau181 were 10.9 pg/mL (179 [34%] of 527 abnormal) on the basis of highest tertile of the baseline distribution, 9.6 pg/mL (241 [46%] of 527 abnormal) on the basis of the prediction of a positive PET amyloid scan, and 12.4 pg/mL (122 [23%] of 527 abnormal) on the basis of the prediction of diagnosis of Alzheimer's dementia during 3-year follow-up.

The median (IQR) p-tau181 concentration did not change between baseline and 3 years in the total sample (8.8 pg/mL [6.7-11.9] vs 8.9 pg/mL [6.5-12.2], p=0.33). Furthermore, there was no strong evidence of differences in mean 3-year change from baseline in p-tau181 between the control group and the three intervention groups (table 2; appendix p 4).

Among patients with normal baseline p-tau181, there was little change in p-tau181 over 3 years in the control group (unadjusted mean [95% CI] 3-year change in p-tau181 -0.16 pg/mL [-1.44 to 1.13] in the models using baseline p-tau cutoffs defined by the highest tertile, -0.12 pg/mL [-1.38 to 1.14] in the models using prediction of PET amyloid positivity, and -0.44 pg/mL [-1.67 to 0.79] in the models using prediction of Alzheimer's dementia; appendix p 5). However, plasma p-tau181 decreased in control group patients with abnormal baseline p-tau181 (unadjusted mean [95% CI]

3-year change in p-tau181 -2.69 pg/mL [effect size 0.63; -4.12 to -1.26] in the models using baseline p-tau cutoffs defined by the highest tertile, -2.06 pg/mL [effect size -0.48; -3.34 to -0.77] in the models using prediction of PET amyloid positivity, and -3.45 pg/mL [effect size 0.81; -5.10 to -1.80] in the models using prediction of Alzheimer's dementia; appendix p 5).

Among patients with normal baseline p-tau181, there was no strong evidence of differences between the control group and the other randomisation groups in 3-year change from baseline in p-tau181 (table 3). Among the patients with abnormal baseline p-tau181, there was weak evidence of between-group differences in some models, but results were inconsistent, and none of the interaction terms implied evidence of overall differences in intervention effects between patients with normal and abnormal baseline p-tau (table 3; appendix p 6).

Similar patterns were observed with all three p-tau181 cutoffs for the unadjusted estimated 3-year trajectories of the composite cognitive score by intervention group and baseline p-tau181 status (appendix pp 12-16).

There was no suggestion of between-randomisation group differences in 3-year change in cognitive function in either the normal or abnormal p-tau181 groups, regardless of the definition used to define abnormal baseline p-tau181 (table 4; appendix pp 7-9). However, in all of the models, there was greater cognitive decline in patients with abnormal baseline p-tau181 compared with those with normal p-tau181 concentrations (eg, in the control group, in the fully adjusted models, mean [95% CI] difference in 3-year cognitive change between participants with normal and abnormal baseline concentrations of p-tau181 was -0.26 [effect size -0.40; -0.50 to -0.03] when using cutoffs defined by the highest tertile, -0.27 [effect size -0.41; -0.50 to -0.04] when using cutoffs defined by prediction of PET amyloid positivity, and -0.34 [effect size -0.52; -0.61 to -0.07] when using cutoffs defined by prediction of Alzheimer's dementia during 3-year follow-up; appendix p 10). The greatest decline in cognitive function amongst participants with raised p-tau181 was observed in the model with the highest p-tau181 cutoff (eg, mean [95% CI] 3-year cognitive change in the control group among patients with abnormal baseline p-tau181 was -0.20 [effect size -0.30; -0.36 to -0.05] when using cutoffs of 9.6 pg/mL, -0.24 [effect size -0.35; -0.41 to -0.06] when using cutoffs of 10.9 pg/mL, and -0.35 [effect size -0.52; -0.57 to -0.12] when using cutoffs of 12.4 pg/mL; table 4, appendix pp 7-9).

## Discussion

In a subsample of older adults from the large randomised controlled MAPT trial, in whom plasma p-tau181 was measured in stored blood samples collected at baseline and the end of the 3-year intervention period, we did not detect any significant effects of a multidomain intervention or omega-3 supplementation on change
<table><thead><tr><th rowspan="2"></th><th colspan="3">p-tau181-negative at baseline</th><th colspan="3">p-tau181-positive at baseline</th><th rowspan="2">p (interaction)</th></tr><tr><th>Multidomain intervention plus omega-3</th><th>Omega-3</th><th>Multidomain intervention</th><th>Multidomain intervention plus omega-3</th><th>Omega-3</th><th>Multidomain intervention</th></tr></thead><tbody><tr><td colspan="8"><strong>1. Tertile cutoff for p-tau181 positivity*</strong></td></tr><tr><td>Number of patients</td><td>92</td><td>75</td><td>87</td><td>40</td><td>46</td><td>32</td><td></td></tr><tr><td>Unadjusted</td><td>0.11 (-0.95 to 1.16)</td><td>0.32 (-0.80 to 1.43)</td><td>0.60 (-0.47 to 1.67)</td><td>1.30 (-0.17 to 2.77)</td><td>1.64 (0.22 to 3.06)</td><td>1.08 (-0.50 to 2.67)</td><td>0.44</td></tr><tr><td>p value†</td><td>0.85</td><td>0.85</td><td>0.82</td><td>0.13</td><td>0.072</td><td>0.18</td><td>..</td></tr><tr><td>Adjustment 1‡</td><td>0.37 (-0.76 to 1.50)</td><td>-0.06 (-1.27 to 1.15)</td><td>0.68 (-0.46 to 1.83)</td><td>1.48 (-0.10 to 3.06)</td><td>1.81 (0.31 to 3.30)</td><td>1.16 (-0.60 to 2.92)</td><td>0.27</td></tr><tr><td>p value†</td><td>0.78</td><td>0.92</td><td>0.73</td><td>0.099</td><td>0.054</td><td>0.20</td><td>..</td></tr><tr><td>Adjustment 2§</td><td>0.38 (-0.75 to 1.50)</td><td>-0.01 (-1.22 to 1.20)</td><td>0.72 (-0.42 to 1.87)</td><td>1.55 (-0.04 to 3.14)</td><td>1.84 (0.35 to 3.33)</td><td>1.15 (-0.61 to 2.91)</td><td>0.26</td></tr><tr><td>p value†</td><td>0.77</td><td>0.99</td><td>0.65</td><td>0.084</td><td>0.048</td><td>0.20</td><td>..</td></tr><tr><td colspan="8"><strong>2. Positive PET amyloid prediction cutoff for p-tau181 positivity¶</strong></td></tr><tr><td>Number of patients</td><td>72</td><td>64</td><td>72</td><td>60</td><td>57</td><td>47</td><td></td></tr><tr><td>Unadjusted</td><td>0.65 (-0.52 to 1.82)</td><td>0.57 (-0.63 to 1.78)</td><td>0.75 (-0.42 to 1.92)</td><td>0.60 (-0.67 to 1.86)</td><td>1.08 (-0.19 to 2.36)</td><td>1.06 (-0.29 to 2.41)</td><td>0.92</td></tr><tr><td>p value†</td><td>0.35</td><td>0.35</td><td>0.35</td><td>0.35</td><td>0.19</td><td>0.19</td><td>..</td></tr><tr><td>Adjustment 1‡</td><td>0.76 (-0.49 to 2.01)</td><td>0.21 (-1.11 to 1.53)</td><td>0.80 (-0.45 to 2.06)</td><td>0.94 (-0.45 to 2.32)</td><td>1.12 (-0.24 to 2.48)</td><td>1.25 (-0.26 to 2.75)</td><td>0.80</td></tr><tr><td>p value†</td><td>0.35</td><td>0.76</td><td>0.35</td><td>0.18</td><td>0.16</td><td>0.16</td><td>..</td></tr><tr><td>Adjustment 2§</td><td>0.75 (-0.49 to 2.00)</td><td>0.24 (-1.08 to 1.56)</td><td>0.83 (-0.43 to 2.08)</td><td>0.99 (-0.40 to 2.39)</td><td>1.16 (-0.20 to 2.52)</td><td>1.27 (-0.23 to 2.77)</td><td>0.81</td></tr><tr><td>p value†</td><td>0.35</td><td>0.72</td><td>0.35</td><td>0.16</td><td>0.14</td><td>0.14</td><td>..</td></tr><tr><td colspan="8"><strong>3. Alzheimer's dementia diagnosis prediction cutoff for p-tau181 positivity||</strong></td></tr><tr><td>Number of patients</td><td>103</td><td>93</td><td>94</td><td>29</td><td>28</td><td>25</td><td></td></tr><tr><td>Unadjusted</td><td>0.29 (-0.68 to 1.25)</td><td>0.70 (-0.29 to 1.69)</td><td>0.71 (-0.27 to 1.71)</td><td>1.99 (0.17 to 3.82)</td><td>1.33 (-0.52 to 3.18)</td><td>2.01 (0.11 to 3.91)</td><td>0.40</td></tr><tr><td>p value†</td><td>0.56</td><td>0.25</td><td>0.25</td><td>0.057</td><td>0.16</td><td>0.057</td><td>..</td></tr><tr><td>Adjustment 1‡</td><td>0.56 (-0.48 to 1.60)</td><td>0.43 (-0.65 to 1.52)</td><td>0.86 (-0.21 to 1.92)</td><td>2.03 (0.06 to 4.00)</td><td>1.45 (-0.48 to 3.38)</td><td>1.81 (-0.31 to 3.94)</td><td>0.62</td></tr><tr><td>p value†</td><td>0.43</td><td>0.43</td><td>0.35</td><td>0.13</td><td>0.14</td><td>0.14</td><td>..</td></tr><tr><td>Adjustment 2§</td><td>0.57 (-0.47 to 1.61)</td><td>0.46 (-0.63 to 1.54)</td><td>0.88 (-0.18 to 1.95)</td><td>2.08 (0.12 to 4.05)</td><td>1.55 (-0.38 to 3.47)</td><td>1.84 (-0.28 to 3.97)</td><td>0.60</td></tr><tr><td>p value†</td><td>0.41</td><td>0.41</td><td>0.31</td><td>0.11</td><td>0.12</td><td>0.12</td><td>..</td></tr></tbody></table>

p-tau181=plasma tau phosphorylated at threonine 181. *≥10.9 pg/mL. †p values are adjusted for multiple comparisons using the Hochberg procedure. ‡Adjustment 1: baseline age, gender, estimated glomerular filtration rate. §Adjustment 2: baseline age, gender, estimated glomerular filtration rate, and APOE genotype. ¶≥9.6 pg/mL. ||≥12.4 pg/mL.

<caption>**Table 3:** Estimated mean difference (95% CI) in 3-year change from baseline in p-tau181 (pg/mL), in the intervention groups versus the control group, by baseline p-tau181 status</caption>

from baseline in plasma p-tau181. Furthermore, we did not detect any intervention effects on 3-year change in cognitive function among participants with raised baseline plasma p-tau181, even though these participants underwent greater cognitive decline than those with normal p-tau181 at baseline.

The lack of change in plasma p-tau181 contrasts with the decrease towards normalisation found with amyloid immunotherapies,¹⁴,¹⁵ and might indicate that these interventions were ineffective in slowing Alzheimer's disease-related pathophysiological changes. However, further studies on the suitability of p-tau181 as a prevention trial outcome measure are also needed. In this setting, as in other settings, baseline plasma p-tau181 differed by age, gender, APOE genotype, and amyloid positivity,²³ and was also predictive of future cognitive decline.¹²,²⁴ Furthermore, our results confirm previously reported associations between kidney function and plasma biomarkers, underlining the potential importance of considering chronic kidney disease, a frequent condition in older populations, when interpreting Alzheimer's disease blood biomarkers.²³,²⁵ However, we observed no change in p-tau181 over 3 years in our total

sample. Although p-tau181 has been shown to increase over time in individuals with Alzheimer's disease dementia,²⁴,²⁶ little to no change has been reported in cognitively unimpaired individuals,²⁴,²⁶ particularly in the absence of amyloid markers.²⁷ Also, p-tau181 has been shown to reach abnormal concentrations several years after amyloid markers,²⁸ possibly suggesting that p-tau181 might be better suited as an outcome measure in trials done in slightly later disease stages. It is possible that we might have obtained different results with other measures of tau in vivo or other measures of plasma p-tau. Plasma p-tau217 has been found to increase with disease progression, whereas both p-tau181 and p-tau231 were longitudinally stable.²⁹ Future studies will tell whether p-tau biomarkers that remain stable in untreated patients are better biomarkers for drug effects than p-tau217 that increases with higher amounts of pathology in the brain.²⁹ Other plasma biomarkers also merit consideration as outcome measures for prevention trials, including glial acidic fibrillary protein, which increases across the Alzheimer's disease continuum from the preclinical stage, might be one of the earliest plasma biomarkers to undergo dynamic changes,³⁰ and decreases
<table><thead><tr><th rowspan="2"></th><th rowspan="2">Unadjusted estimated mean within-group change from baseline (95% CI)</th><th colspan="6">Estimated mean difference (95% CI) in 3-year change compared to control group</th></tr><tr><th>Unadjusted</th><th>p*</th><th>Adjustment 1†</th><th>p*</th><th>Adjustment 2‡</th><th>p*</th></tr></thead><tbody><tr><td colspan="8"><strong>1. Tertile cutoff for p-tau181 abnormality</strong></td></tr><tr><td colspan="8">Normal baseline p-tau181 (&lt;10.9 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>0.10 (-0.02 to 0.23)</td><td>0.08 (-0.11 to 0.26)</td><td>0.80</td><td>0.07 (-0.13 to 0.26)</td><td>0.79</td><td>0.07 (-0.13 to 0.26)</td><td>0.90</td></tr><tr><td>Omega-3</td><td>0.00 (-0.14 to 0.14)</td><td>-0.03 (-0.22 to 0.17)</td><td>0.80</td><td>-0.06 (-0.27 to 0.15)</td><td>0.79</td><td>-0.07 (-0.27 to 0.14)</td><td>0.90</td></tr><tr><td>Multidomain intervention</td><td>-0.02 (-0.15 to 0.11)</td><td>-0.05 (-0.23 to 0.14)</td><td>0.80</td><td>-0.03 (-0.23 to 0.17)</td><td>0.79</td><td>-0.01 (-0.21 to 0.18)</td><td>0.90</td></tr><tr><td>Control</td><td>0.02 (-0.11 to 0.16)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Abnormal baseline p-tau181 (≥10.9 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>-0.12 (-0.31 to 0.08)</td><td>0.12 (-0.14 to 0.38)</td><td>0.73</td><td>0.13 (-0.14 to 0.41)</td><td>0.75</td><td>0.12 (-0.15 to 0.40)</td><td>0.73</td></tr><tr><td>Omega-3</td><td>-0.28 (-0.45 to -0.10)</td><td>-0.04 (-0.29 to 0.20)</td><td>0.73</td><td>0.04 (-0.22 to 0.30)</td><td>0.75</td><td>0.05 (-0.21 to 0.30)</td><td>0.73</td></tr><tr><td>Multidomain intervention</td><td>-0.30 (-0.52 to -0.08)</td><td>-0.07 (-0.35 to 0.22)</td><td>0.73</td><td>0.05 (-0.26 to 0.36)</td><td>0.75</td><td>0.05 (-0.25 to 0.36)</td><td>0.73</td></tr><tr><td>Control</td><td>-0.24 (-0.41 to -0.06)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Interaction: between-subgroup difference in intervention effect (vs control)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td></td><td>0.04 (-0.28 to 0.36)</td><td>0.80</td><td>0.07 (-0.27 to 0.41)</td><td>0.69</td><td>0.05 (-0.28 to 0.39)</td><td>0.75</td></tr><tr><td>Omega-3</td><td></td><td>-0.02 (-0.33 to 0.29)</td><td>0.91</td><td>0.10 (-0.23 to 0.44)</td><td>0.54</td><td>0.11 (-0.22 to 0.45)</td><td>0.50</td></tr><tr><td>Multidomain intervention</td><td></td><td>-0.02 (-0.36 to 0.32)</td><td>0.91</td><td>0.08 (-0.29 to 0.44)</td><td>0.68</td><td>0.07 (-0.30 to 0.43)</td><td>0.72</td></tr><tr><td colspan="8"><strong>2. Positive PET amyloid prediction cutoff for p-tau181 abnormality</strong></td></tr><tr><td colspan="8">Normal baseline p-tau181 (&lt;9.6 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>0.11 (-0.03 to 0.26)</td><td>0.07 (-0.13 to 0.27)</td><td>0.99</td><td>0.03 (-0.18 to 0.25)</td><td>0.75</td><td>0.04 (-0.18 to 0.25)</td><td>0.73</td></tr><tr><td>Omega-3</td><td>0.04 (-0.11 to 0.19)</td><td>0.00 (-0.21 to 0.21)</td><td>0.99</td><td>-0.04 (-0.26 to 0.19)</td><td>0.75</td><td>-0.05 (-0.27 to 0.18)</td><td>0.73</td></tr><tr><td>Multidomain intervention</td><td>-0.03 (-0.17 to 0.11)</td><td>-0.07 (-0.27 to 0.13)</td><td>0.99</td><td>-0.07 (-0.28 to 0.15)</td><td>0.75</td><td>-0.06 (-0.27 to 0.16)</td><td>0.73</td></tr><tr><td>Control</td><td>0.04 (-0.10 to 0.19)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Abnormal baseline p-tau181 (≥9.6 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>-0.06 (-0.21 to 0.10)</td><td>0.15 (-0.07 to 0.37)</td><td>0.55</td><td>0.17 (-0.07 to 0.41)</td><td>0.47</td><td>0.16 (-0.07 to 0.40)</td><td>0.53</td></tr><tr><td>Omega-3</td><td>-0.27 (-0.42 to -0.11)</td><td>-0.06 (-0.28 to 0.16)</td><td>0.90</td><td>0.00 (-0.24 to 0.23)</td><td>0.99</td><td>0.01 (-0.23 to 0.24)</td><td>0.96</td></tr><tr><td>Multidomain intervention</td><td>-0.19 (-0.37 to -0.01)</td><td>0.01 (-0.22 to 0.25)</td><td>0.90</td><td>0.12 (-0.14 to 0.37)</td><td>0.73</td><td>0.13 (-0.13 to 0.38)</td><td>0.65</td></tr><tr><td>Control</td><td>-0.20 (-0.36 to -0.05)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Interaction: between-subgroup difference in intervention effect (vs control)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td></td><td>0.08 (-0.22 to 0.38)</td><td>0.61</td><td>0.14 (-0.19 to 0.46)</td><td>0.40</td><td>0.13 (-0.20 to 0.45)</td><td>0.44</td></tr><tr><td>Omega-3</td><td></td><td>-0.06 (-0.36 to 0.24)</td><td>0.69</td><td>0.04 (-0.29 to 0.36)</td><td>0.83</td><td>0.05 (-0.27 to 0.38)</td><td>0.74</td></tr><tr><td>Multidomain intervention</td><td></td><td>0.08 (-0.23 to 0.39)</td><td>0.60</td><td>0.18 (-0.15 to 0.52)</td><td>0.28</td><td>0.18 (-0.15 to 0.51)</td><td>0.28</td></tr><tr><td colspan="8"><strong>3. Alzheimer's dementia diagnosis prediction cutoff for p-tau181 abnormality</strong></td></tr><tr><td colspan="8">Normal baseline p-tau181 (&lt;12.4 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>0.10 (-0.02 to 0.22)</td><td>0.09 (-0.07 to 0.26)</td><td>0.81</td><td>0.09 (-0.09 to 0.27)</td><td>0.92</td><td>0.09 (-0.09 to 0.27)</td><td>0.93</td></tr><tr><td>Omega-3</td><td>0.01 (-0.11 to 0.13)</td><td>0.01 (-0.16 to 0.18)</td><td>0.94</td><td>-0.02 (-0.20 to 0.17)</td><td>0.995</td><td>-0.03 (-0.22 to 0.15)</td><td>0.93</td></tr><tr><td>Multidomain intervention</td><td>-0.02 (-0.14 to 0.10)</td><td>-0.02 (-0.19 to 0.15)</td><td>0.94</td><td>0.00 (-0.18 to 0.18)</td><td>0.995</td><td>0.01 (-0.17 to 0.19)</td><td>0.93</td></tr><tr><td>Control</td><td>0.00 (-0.11 to 0.12)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Abnormal baseline p-tau181 (≥12.4 pg/mL)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td>-0.18 (-0.41 to 0.04)</td><td>0.16 (-0.15 to 0.48)</td><td>0.83</td><td>0.13 (-0.21 to 0.48)</td><td>0.96</td><td>0.13 (-0.21 to 0.47)</td><td>0.86</td></tr><tr><td>Omega-3</td><td>-0.46 (-0.68 to -0.25)</td><td>-0.12 (-0.43 to 0.19)</td><td>0.83</td><td>-0.01 (-0.34 to 0.32)</td><td>0.96</td><td>0.03 (-0.30 to 0.36)</td><td>0.86</td></tr><tr><td>Multidomain intervention</td><td>-0.38 (-0.64 to -0.13)</td><td>-0.04 (-0.37 to 0.30)</td><td>0.83</td><td>0.08 (-0.29 to 0.45)</td><td>0.96</td><td>0.10 (-0.26 to 0.46)</td><td>0.86</td></tr><tr><td>Control</td><td>-0.35 (-0.57 to -0.12)</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td><td>..</td></tr><tr><td colspan="8">Interaction: between-subgroup difference in intervention effect (vs control)</td></tr><tr><td>Multidomain intervention plus omega-3</td><td></td><td>0.07 (-0.29 to 0.43)</td><td>0.70</td><td>0.04 (-0.35 to 0.43)</td><td>0.84</td><td>0.04 (-0.34 to 0.42)</td><td>0.84</td></tr><tr><td>Omega-3</td><td></td><td>-0.12 (-0.48 to 0.23)</td><td>0.50</td><td>0.01 (-0.37 to 0.39)</td><td>0.96</td><td>0.06 (-0.31 to 0.44)</td><td>0.75</td></tr><tr><td>Multidomain intervention</td><td></td><td>-0.01 (-0.39 to 0.37)</td><td>0.95</td><td>0.08 (-0.34 to 0.49)</td><td>0.72</td><td>0.09 (-0.31 to 0.50)</td><td>0.66</td></tr></tbody></table>

p-tau181=plasma tau phosphorylated at threonine 181. *p values for between-group comparisons are adjusted for multiple comparisons using the Hochberg procedure. †Adjustment 1: baseline age, gender, estimated glomerular filtration rate, and their interactions with time. ‡Adjustment 2: baseline age, gender, estimated glomerular filtration rate, APOE genotype, and their interactions with time.

<caption>**Table 4:** Intervention effects on 3-year change in cognitive function (composite cognitive Z score) according to baseline p-tau181 status</caption>
with anti-amyloid immunotherapy in early clinical Alzheimer's disease.¹⁵

Our subgroup analyses showed a significant decrease in p-tau181 over 3 years in control group patients who had raised p-tau181 at baseline, whereas a previous study suggested that there was a greater increase in p-tau181 over time with increasing baseline concentrations.²⁸ The robustness of our longitudinal measures might therefore require evaluation. The effect of pre-analytical procedures could be questioned, particularly since these analyses were done on stored blood samples that were not specifically collected for p-tau181 analysis. However, the recommended number of freeze-thaw cycles was not exceeded,³¹ and the same edetic acid tube types were used at both timepoints.

We also found no intervention effects on a composite cognitive score in participants with raised baseline p-tau181, despite the fact that a previous MAPT subgroup analysis suggested a possible beneficial effect of the multidomain intervention, alone or in combination with omega-3 fatty acid supplementation, on cognitive function in individuals with PET evidence of amyloid pathology.⁵,⁶ Although plasma p-tau appears to be a specific marker of Alzheimer's disease pathophysiology,¹¹ and correlates with amyloid, it is not a directly interchangeable marker for PET amyloid. If preventive multidomain interventions are indeed most effective at a certain stage of accumulation of Alzheimer's disease-related proteins, it might be that p-tau181 does not specifically detect this key stage, or that we did not use the correct cutpoints to identify this stage. Indeed, the cutpoints we used to establish abnormal concentrations of p-tau181 were not validated or defined a priori, and have been defined differently in other studies.²⁶ Nonetheless, we used three different cutoffs, all of which showed greater cognitive decline in individuals with abnormal baseline p-tau181, and cognitive decline was greatest with the highest cutoff.

To the best of our knowledge, this is the first reported study evaluating p-tau181 in a multidomain prevention trial setting. Further strengths include the relatively large and well characterised study population, and the longitudinal measurement of p-tau181. However, given that we selected participants with available 3-year data, who were in better health at baseline than those who were excluded from this analysis, and that multidomain prevention trial participants in general are not representative of the general older population,¹² selection bias might have affected our results. There were no between-group differences in baseline characteristics, but it is possible that our results could have been biased by unmeasured confounders. Also, although our sample size was relatively large compared with previous Alzheimer's disease biomarker substudies of multidomain trials,⁵,⁷⁻⁹ formal power calculations were not done, and the subgroup analysis based on baseline p-tau181 status was, in particular, likely to be

underpowered. Sample sizes precluded further subgroup analyses on the basis of amyloid positivity or trial eligibility criteria. Finally, a longer intervention period could be required to detect the effects on p-tau181.

In conclusion, we did not find any evidence that a multidomain intervention, omega-3 supplementation, or both interventions combined affected longitudinal trajectories of plasma p-tau181 in a population of older adults with normal cognition or mild cognitive impairment participating in a prevention trial, nor that these interventions had any effect on cognitive decline or p-tau trajectories in individuals with raised baseline concentrations of p-tau181. These findings contrast the decrease towards normalisation in plasma p-tau181 seen with anti-amyloid immunotherapies. Further investigation of the usefulness of plasma p-tau181 as an outcome measure for prevention trials is also required, in particular in studies in which amyloid positivity is measured in a bigger sample. Our results did, however, support the growing evidence of the utility of p-tau181 as a prognostic biomarker.

**The members of the MAPT study group**

**Principal investigator:** Bruno Vellas (Toulouse). **Coordination:**

Sophie Guyonnet; Project leader: Isabelle Carrié. CRA: Lauréane Brigitte.

Investigators: Catherine Faisant, Françoise Lala, Julien Delrieu,

Hélène Villars. Psychologists: Emeline Combrouze, Carole Badufle,

Audrey Zueras. Methodology, statistical analysis, and data management:

Sandrine Andrieu, Christelle Cantet, Christophe Morin. Multidomain group: Gabor Abellan Van Kan, Charlotte Dupuy, Yves Rolland (physical and nutritional components), Céline Caillaud, Pierre-Jean Ousset (cognitive component), Françoise Lala (preventive consultation). The cognitive component was designed in collaboration with Sherry Willis from the University of Seattle, and Sylvie Belleville, Brigitte Gilbert, and Francine Fontaine from the University of Montreal.

Co-Investigators in associated centres: Jean-François Dartigues, Isabelle Marcet, Fleur Delva, Alexandra Foubert, Sandrine Cerda (Bordeaux); Marie-Noëlle Cuffi, Corinne Costes (Castres);

Olivier Rouaud, Patrick Manckoundia, Valérie Quipourt, Sophie Marilier,

Evelyne Franon (Dijon); Lawrence Bories, Marie-Laure Pader,

Marie-France Basset, Bruno Lapoujade, Valérie Faure,

Michael Li Yung Tong, Christine Malick-Loiseau,

Evelyne Cazaban-Campistron (Foix); Françoise Desclaux, Colette Blatge (Lavaur); Thierry Dantoin, Cécile Laubarie-Mouret, Isabelle Saulnier,

Jean-Pierre Clément, Marie-Agnès Picat, Laurence Bernard-Bourzeix,

Stéphanie Willebois, Iléana Désormais, Noëlle Cardinaud (Limoges);

Marc Bonnefoy, Pierre Livet, Pascale Rebaudet, Claire Gédéon,

Catherine Burdet, Flavien Terracol (Lyon); Alain Pesce, Stéphanie Roth,

Sylvie Chaillou, Sandrine Louchart (Monaco); Kristel Sudres,

Nicolas Lebrun, Nadège Barro-Belaygues (Montauban);

Jacques Touchon, Karim Bennys, Audrey Gabelle, Aurélia Romano,

Lynda Touati, Cécilia Marelli, Cécile Pays (Montpellier); Philippe Robert,

Franck Le Duff, Claire Gervais, Sébastien Gonfrier (Nice);

Yannick Gasnier, Serge Bordes, Danièle Begorre, Christian Carpuat,

Khaled Khales, Jean-François Lefebvre, Samira Misbah El Idrissi,

Pierre Skolil, Jean-Pierre Salles (Tarbes). MRI group: Carole Dufouil (Bordeaux);

Stéphane Lehéricy, Marie Chupin, Jean-François Mangin,

Ali Bouhayia (Paris); Michèle Allard (Bordeaux); Frédéric Ricolfi (Dijon);

Dominique Dubois (Foix); Marie Paule Bonceour Martel (Limoges);

François Cotton (Lyon); Alain Bonafé (Montpellier); Stéphane Chanalet (Nice);

Françoise Hugon (Tarbes); Fabrice Bonneville,

Christophe Cognard, François Chollet (Toulouse). PET scans group:

Pierre Payoux, Thierry Voisin, Julien Delrieu, Sophie Peiffer,

Anne Hitzel, (Toulouse); Michèle Allard (Bordeaux); Michel Zanca (Montpellier); Jacques Monteil (Limoges); Jacques Darcourt (Nice).

Medico-economics group: Laurent Molinier, Hélène Derumeaux,

Nadège Costa (Toulouse). Biological sample collection: Bertrand Perret,
Claire Vinel, Sylvie Caspar-Bauguil (Toulouse). Safety management: Pascale Olivier-Abbal. DSA Group: Sandrine Andrieu, Christelle Cantet, Nicola Coley.

### Contributors

NC, SA, BV, and SG designed the study. BV and SG collected the data. NC, CC, HZ, NJA, and KB analysed the data. NC and CC produced the figures. All authors were responsible for interpreting the data and critically revising the manuscript. NC wrote the draft. BV was responsible for funding acquisition. NC and CC directly assessed and verified the underlying data reported in the manuscript. All authors had full access to all the data in the study and had final responsibility for the decision to submit for publication.

### Declaration of interests

HZ has served on scientific advisory boards or as a consultant, or both for AbbVie, Acumen, Alector, Alzinova, ALZPath, Annexon, Apellis, Artery Therapeutics, AZTherapies, CogRx, Denali, Eisai, Nervgen, Novo Nordisk, Optocaceutics, Passage Bio, Pinteon Therapeutics, Prothena, Red Abbey Labs, reMYND, Roche, Samumed, Siemens Healthineers, Triplet Therapeutics, and Wave; has given lectures in symposia sponsored by Cellectron, Fujirebio, Alzsecure, Biogen, and Roche; and is a co-founder of Brain Biomarker Solutions in Gothenburg, which is a part of the GU Ventures Incubator Program (outside the submitted work). KB has served as a consultant and on advisory boards for Acumen, ALZPath, BioArctic, Biogen, Eisai, Julius Clinical, Lilly, Novartis, Ono Pharma, Prothena, Roche Diagnostics, and Siemens Healthineers; has served at data monitoring committees for Julius Clinical and Novartis; has given lectures, produced educational materials, and participated in educational programmes for Biogen, Eisai, and Roche Diagnostics; and is a co-founder of Brain Biomarker Solutions in Gothenburg, which is a part of the GU Ventures Incubator Program, outside the work presented in this paper. BV is an investigator in clinical trials sponsored by Biogen, Lilly, Roche, Eisai, Pfizer, Pierre Fabre Pharmaceuticals, and Toulouse University Hospital; has served as a scientific advisory board member for Biogen, Alzheon, Green Valley, Novo Nordisk, Longeveron, Rejuvenate Biomed Clinical Pfizer, Eisai France, and Pierre Fabre Advisory Board Meeting—but received no personal compensation; has served as a consultant or scientific advisory board member, or both for Roche, Lilly, Eisai, TauX, and Cerecin with personal compensation, outside of the submitted work. SA reports grants from EU programmes (H2020, JPND), Fondation de l'avenir, Fondation Vaincre Alzheimer, France Alzheimer, and personal fees from Biogen, Roche, and AXA mutuelle in the last 3 years, outside of the submitted work. All other authors declare no competing interests.

### Data sharing

Individual de-identified participant data that underlie the present study are available with immediate effect to academic researchers, following approval of a methodologically sound research proposal by the MAPT data sharing committee and signature of a data access agreement. Enquiries or proposals should be directed to nicola.coley@inserm.fr and guyonnet.s@chu-toulouse.fr.

### Acknowledgments

The MAPT study was supported by grants from the Gérontopôle of Toulouse, the French Ministry of Health (PHRC 2008, 2009), Pierre Fabre Research Institute (manufacturer of the omega-3 supplement), ExonHit Therapeutics SA, and Avid Radiopharmaceuticals. The promotion of this study was supported by Toulouse University Hospital. KB is supported by the Swedish Research Council (#2017-00915 and #2022-00732), the Swedish Alzheimer Foundation (#AF-930351, #AF-939721, and #AF-968270), Hjärnfonden, Sweden (#FO2017-0243 and #ALZ2022-0006), the Swedish state under the agreement between the Swedish Government and the County Councils, the ALF-agreement (#ALFGBG-715986 and #ALFGBG-965240), the EU Joint Program for Neurodegenerative Disorders (JPND2019-466-236), the Alzheimer's Association 2021 Zenith Award (ZEN-21-848495), and the Alzheimer's Association 2022-2025 Grant (SG-23-1038904 QC). HZ is a Wallenberg Scholar supported by grants from the Swedish Research Council (#2022-01018 and #2019-02397), the EU's Horizon Europe research and innovation programme under grant agreement number 101053962, Swedish State Support for Clinical Research (#ALFGBG-71320), the

Alzheimer Drug Discovery Foundation, USA (#201809-2016862), the AD Strategic Fund and the Alzheimer's Association (#ADSF-21-831376-C, #ADSF-21-831381-C, and #ADSF-21-831377-C), the Bluefield Project, the Olav Thon Foundation, the Erling-Persson Family Foundation, Stiftelsen for Gamla Tjäraninnor, Hjärnfonden, Sweden (#FO2022-0270), the EU's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 860197 (MIRIADE), the European Union Joint Programme—Neurodegenerative Disease Research (JPND2021-00694), and the UK Dementia Research Institute at UCL (UKDRI-1003).

### References

1. Livingston G, Huntley J, Sommerlad A, et al. Dementia prevention, intervention, and care: 2020 report of the *Lancet* Commission. *Lancet* 2020; **396**: 413–46.

2. Coley N, Giuloli C, Aisen PS, Vellas B, Andrieu S. Randomised controlled trials for the prevention of cognitive decline or dementia: a systematic review. *Ageing Res Rev* 2022; **82**: 10177–10179.

3. Perus L, Busto GU, Mangin JF, Le Bars E, Gabelle A. Effects of preventive interventions on neuroimaging biomarkers in subjects at-risk to develop Alzheimer's disease: a systematic review. *Front Aging Neurosci* 2022; **14**: 1014559.

4. Hooper C, Coley N, De Souto Barreto P, et al. Cortical β-amyloid in older adults is associated with multidomain interventions with and without omega 3 polyunsaturated fatty acid supplementation. *J Prev Alzheimers Dis* 2020; **7**: 128–34.

5. Delrieu J, Payoux P, Carrière I, et al. Multidomain intervention and/or omega-3 in nondemented elderly subjects according to amyloid status. *Alzheimers Dement* 2019; **15**: 1392–401.

6. Andrieu S, Guyonnet S, Coley N, et al. Effect of long-term omega 3 polyunsaturated fatty acid supplementation with or without multidomain intervention on cognitive function in elderly adults with memory complaints (MAPT): a randomised, placebo-controlled trial. *Lancet Neurol* 2017; **16**: 377–89.

7. Delrieu J, Voisin T, Saint-Aubert L, et al. The impact of a multi-domain intervention on cerebral glucose metabolism: analysis from the randomized ancillary FDG PET MAPT trial. *Alzheimers Res Ther* 2020; **12**: 134.

8. Stephen R, Solomon A, Ngandu T, et al. White matter changes on diffusion tensor imaging in the FINGER randomized controlled trial. *J Alzheimers Dis* 2020; **78**: 75–86.

9. Stephen R, Liu Y, Ngandu T, et al. Brain volumes and cortical thickness on MRI in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER). *Alzheimers Res Ther* 2019; **11**: 53.

10. Teunissen CE, Verberk IMW, Thijssen EH, et al. Blood-based biomarkers for Alzheimer's disease: towards clinical implementation. *Lancet Neurol* 2022; **21**: 66–77.

11. Karikari TK, Ashton NJ, Brinkmalm G, et al. Blood phospho-tau in Alzheimer disease: analysis, interpretation, and clinical utility. *Nat Rev Neurol* 2022; **18**: 400–18.

12. Karikari TK, Pascoal TA, Ashton NJ, et al. Blood phosphorylated tau 181 as a biomarker for Alzheimer's disease: a diagnostic performance and prediction modelling study using data from four prospective cohorts. *Lancet Neurol* 2020; **19**: 422–33.

13. Ossenkoppele R, van der Kant R, Hansson O. Tau biomarkers in Alzheimer's disease: towards implementation in clinical practice and trials. *Lancet Neurol* 2022; **21**: 726–34.

14. Budd Haeberlein S, Aisen PS, Barkhof F, et al. Two randomized phase 3 studies of aducanumab in early Alzheimer's disease. *J Prev Alzheimers Dis* 2022; **9**: 197–210.

15. van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in early Alzheimer's disease. *N Engl J Med* 2023; **388**: 9–21.

16. Lawton MP, Brody EM. Assessment of older people: self-maintaining and instrumental activities of daily living. *Gerontologist* 1969; **9**: 179–86.

17. Gillette-Guyonnet S, Andrieu S, Dantoine T, Dartigues JF, Touchon J, Vellas B. Commentary on “A roadmap for the prevention of dementia II. Leon Thal Symposium 2008.” The Multidomain Alzheimer Preventive Trial (MAPT): a new approach to the prevention of Alzheimer's disease. *Alzheimers Dement* 2009; **5**: 114–21.

18. Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in the aged. The Index of Adl: a standardized measure of biological and psychosocial function. *JAMA* 1963; **185**: 914–19.
19 Vellas B, Carrie I, Gillette-Guyonnet S, et al. MAPT study: a multidomain approach for preventing Alzheimer's disease: design and baseline data. *J Prevent Alzheimer Dis* 2014; **1**: 13-22.

20 Payoux P, Delrieu J, Gallini A, et al. Cognitive and functional patterns of nondemented subjects with equivocal visual amyloid PET findings. *Eur J Nucl Med Mol Imaging* 2015; **42**: 1459-68.

21 Fleisher AS, Chen K, Liu X, et al. Using positron emission tomography and florbetapir F18 to image cortical amyloid in patients with mild cognitive impairment or dementia due to Alzheimer disease. *Arch Neurol* 2011; **68**: 1404-11.

22 Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate glomerular filtration rate. *Ann Intern Med* 2009; **150**: 604-12.

23 Mielke MM, Dage JL, Frank RD, et al. Performance of plasma phosphorylated tau 181 and 217 in the community. *Nat Med* 2022; **28**: 1398-405.

24 Simrén J, Leuzy A, Karikari TK, et al. The diagnostic and prognostic capabilities of plasma biomarkers in Alzheimer's disease. *Alzheimers Dement* 2021; **17**: 1145-56.

25 Pajewski NM, Elahi FM, Tamura MK, et al. Plasma amyloid beta, neurofilament light chain, and total tau in the Systolic Blood Pressure Intervention Trial (SPRINT). *Alzheimers Dement* 2022; **18**: 1472-83.

26 Lantero Rodriguez J, Karikari TK, Suárez-Calvet M, et al. Plasma p-tau181 accurately predicts Alzheimer's disease pathology at least 8 years prior to post-mortem and improves the clinical characterisation of cognitive decline. *Acta Neuropathol* 2020; **140**: 267-78.

27 Chatterjee P, Pedrini S, Ashton NJ, et al. Diagnostic and prognostic plasma biomarkers for preclinical Alzheimer's disease. *Alzheimers Dement* 2022; **18**: 1141-54.

28 Moscoso A, Grothe MJ, Ashton NJ, et al. Time course of phosphorylated-tau181 in blood across the Alzheimer's disease spectrum. *Brain* 2021; **144**: 325-39.

29 Ashton NJ, Janelidze S, Mattsson-Carlgren N, et al. Differential roles of Aβ42/40, p-tau231 and p-tau217 for Alzheimer's trial selection and disease monitoring. *Nat Med* 2022; **28**: 2555-62.

30 Benedet AL, Milà-Alomà M, Vrillon A, et al. Differences between plasma and cerebrospinal fluid glial fibrillary acidic protein levels across the Alzheimer disease continuum. *JAMA Neurol* 2021; **78**: 1471-83.

31 Ashton NJ, Suárez-Calvet M, Karikari TK, et al. Effects of pre-analytical procedures on blood biomarkers for Alzheimer's pathophysiology, glial activation, and neurodegeneration. *Alzheimers Dement (Amst)* 2021; **13**: e12168.

32 Coley N, Coniasse-Brioude D, Igier V, et al. Disparities in the participation and adherence of older adults in lifestyle-based multidomain dementia prevention and the motivational role of perceived disease risk and intervention benefits: an observational ancillary study to a randomised controlled trial. *Alzheimers Res Ther* 2021; **13**: 157.