Original Article

Preliminary evaluation of the Japanese version of the Cognitive Function Instrument
in a memory clinic
Tohmi Osaki1,2, Yasuji Yamamoto3,4, Hisatomo Kowa5, Shinsuke Kojima6, Kiyoshi Maeda2, Hiroyuki Kajita2,
Yasumasa Kakei7, and Yoji Nagai8,9Abstract
Background: Early detection of dementia and mild cognitive impairment (MCI) is important for early and effective intervention. This
study aimed to conduct a preliminary evaluation of the utility of the Japanese version of the Cognitive Function Instrument (CFI-J),
which is a self-administered questionnaire that sensitively detects decline in activities of daily living due to minor cognitive decline.
Methods: Twenty outpatients (6 cognitively normal and 14 with MCI) at a single memory clinic participated; patients rated themselvesin the self-CFI-J, and were rated by accompanying family members in the partner-CFI-J. On the same day, neuropsychological tests (i.e.
the Alzheimer’s Disease Assessment Scale-Cognitive Subscale, Logical Memory I & II of the Wechsler Memory Scale-Revised, MiniMental Examination, Clinical Dementia Rating, Frontal Assessment Battery, and the Geriatric Depression Scale-15) were also
administered to patients, and a second CFI-J was administered approximately one month later.
Results: The intra-class correlation coefficient (95% confidence interval) of the CFI-J at the one-month interval was .442 [.008, .739]
for the self-CFI-J and .811 [.566, .925] for the partner-CFI-J. The MCI group had a significantly higher partner-CFI-J score than the
cognitively normal group. Both the self-CFI-J and partner-CFI-J scores were not correlated with any of the neuropsychological test scores.
Conclusion: The present study confirmed the test-retest reliability of the CFI-J. The partner-CFI-J adequately reflected the patients’ stageof cognitive functioning. However, concurrent validity with neuropsychological tests was not confirmed, suggesting that use of the CFIJ as a self-administered questionnaire in patients with obvious memory impairment should be treated with caution.
Keywords : Activities of daily living, dementia, mild cognitive impairment, test-retest reliability, screening

Introduction
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2021 年 7 月 8 日受付，2021 年 9 月 24 日受理
Department of Psychiatry, Kobe University Graduate
School of Medicine
Faculty of Rehabilitation, Kobe Gakuin University
Department of Biosignal Pathophysiology, Kobe
University Graduate School of Medicine
Medical Centre for Student Health, Kobe University
Division of Cognitive and Psychiatric Rehabilitation,
Department of Rehabilitation Science, Kobe
University Graduate School of Health Sciences
Translational Research Centre for Medical Innovation,
Foundation for Biomedical Research and Innovation,
Kobe
Clinical and Translational Research Centre, Kobe
University Hospital
Division of Translational Science, Kobe University
Graduate School of Medicine
Department of Clinical Research Facilitation, Institutefor Advancement of Clinical and Translational
Science (iACT), Kyoto University Hospital

Alzheimer’s disease (AD), a typical degenerative disease thatinduces dementia, is often preceded by a preclinical phase in which
there are changes in the brain (e.g. accumulation of beta-amyloid)
but no clinical symptoms1). It is also often preceded by a prodromalphase (mild cognitive impairment [MCI]), in which there is
objective cognitive decline but no decline in activities of dailyliving (ADL). Early identification of high-risk individuals in the
preclinical or prodromal stages of dementia is very important.
Previous studies have shown that interventions such as physicalexercise and nutritional management can help revert older adults
with MCI or minor cognitive decline back to normal cognitive
function2). Furthermore, the target of drug discovery for diseasemodifying drugs has shifted to the prodromal or preclinical stages
due to the development of research on biological biomarkers suchas beta-amyloid and tau levels in the cerebrospinal fluid3). It is very
important to detect MCI or minor cognitive decline as early as
possible and to prevent the progression to dementia (or delay theonset of dementia) through early therapeutic interventions, as this-2-Preliminary evaluation of the Japanese version of the Cognitive Function Instrument in a memory clinic

Methods

will not only benefit the patients but will also reduce social burdens

Subjects

1)such as national health care costs .
Neuropsychological testing is a reasonable method for detecting

Among those who visited the memory clinic at Kobe University

cognitive decline. However, the Mini-Mental State Examination

Hospital during the study period from December 2016 to August(MMSE), which is widely used as a screening test for cognitive

2020, subjects were selected based on specific selection andfunction, does not have sufficient sensitivity or specificity to detectexclusion criteria. The selection criteria were as follows: (1)4)

MCI, and is not very effective in detecting minor changes . By

outpatients whose general cognitive function was judged by theircontrast, complex cognitive function tests such as the Alzheimer’s

physician, who was a dementia specialist, to be at the normal or

Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and

MCI level; (2) patients who were scheduled to undergo a set of

the Wechsler Memory Scale-Revised (WMS-R) can provide

neuropsychological tests at the memory clinic (see below); (3)detailed assessments; however, these tests have limitations, such as

those who lived with or had a family attendant who had contact

the long time required to complete them and the need for a skilledwith the patient at least twice a week; and (4) those who verbally

examiner. In addition, all of the neuropsychological tests referredagreed to participate in the study. The exclusion criteria were as

to above can only be performed when patients or family members

follows: (1) those judged to have obvious intra- or inter-day

complain of subjective cognitive decline and visit a specialist in afluctuations in their cognitive function level; (2) those diagnosed as

hospital. If it were possible to detect minor cognitive decline andhaving schizophrenia, mood disorders, or other psychiatricrisk of future cognitive decline more easily early on, that is, indisorders; and (3) those judged inappropriate for participation in thecommunity-based health check-ups, it would be possible tostudy for other reasons. After a series of routine examinations,provide earlier therapeutic intervention.

patients with higher abilities were diagnosed as cognitively normal.

In response to this issue, a research group from the Alzheimer’s

Others were diagnosed with MCI according to the following

Disease Cooperative Study (ADCS) developed the Cognitive

criteria: (1) patients with a score missing on the MMSE, a clinicalFunction Instrument (CFI) as an assessment method to sensitively

dementia rating (CDR) of 0.5 and an ADAS-Cog of less than 15;

detect decline in ADL abilities due to cognitive decline, and(2) considering the patient's educational history and pre-morbid

reported its potential utility in February 20155). The CFI can be usedabilities, a score of only serial 7 on the MMSE was not treated as aby self-administration, interviews, or telephonically and consists ofscore loss; (3) a clear decrease in the score of II from the score of I

14 questions about daily life. In addition to the self-CFI, which isin the Logical Memory of the WMS-R; and (4) no obvious

answered by the subjects themselves, the partner-CFI, which isdepressive symptoms. The subjects were orally informed of theanswered by a person who is familiar with the subject’s living

study by their physicians, and oral informed consent was obtained

situation, has been developed, and the total score of both versions

and recorded in their medical records. This study was approved by

5)of the CFI can be calculated. In a previous study , 468 elderly

the ethics review committee of Kobe University Hospital.

people who were considered cognitively normal at baseline were

A total of 21 dyads were collected, of which one dyad was

followed up for four years and assessed with the CFI at baseline

excluded from the analysis because the patient was judged to be

and annually, in addition to being assessed using various

cognitively normal but significantly depressed, according to aneuropsychological tests. It was found that the subjects’ CFI scores

medical record data check following data collection. Consequently,

at baseline were significantly worse (higher) in the group that

20 dyads were analysed.

developed MCI or dementia during the follow-up period than in thegroup that did not, and that CFI scores in the group that developed

Cognitive Function Instrument-Japanese version (CFI-J)

MCI or dementia worsened (increased) over time. Thus, the CFIFirst, we obtained permission from the original author of the

may be useful as an assessment method for detecting decline in

Mail-In Cognitive Function Screening Instrument (MCFSI)8), theADL abilities that are due to cognitive decline from the stage before

original version of the CFI, to translate and use it in the Japanese6)clinical diagnosis of MCI or dementia. The Norwegian andversion. The self-CFI and partner-CFI questions were translated

7)

Italian versions of this test have already been developed, and theirinto Japanese by two physicians specialising in dementia and one

reliability and validity have been confirmed.

physician specialising in clinical research, both affiliated withIn this study, we developed a Japanese version of the CFI, which

Kobe University. In the original version of the self-CFI, questionso far has not been translated, and conducted a preliminary

10 was “Has your work performance (paid or volunteer) declined

evaluation of its utility by examining its test-retest reliability andsignificantly comparedto one year ago?” However, invalidity in the memory clinic at Kobe University Hospital.

consideration of the difference in cultural and linguistic nuance,-3-一般社団法人

日本認知症予防学会誌
Vol.11 No.2, 2021

this question was changed in the self CFI-J to “Has your work(FAB), and geriatric depression scale-15 (GDS). For reasons such(paid or volunteer) or household chore performance declined

as limited clinical time, some of the tests in the neuropsychologicalsignificantly compared to one year ago?” The same change wastest set may have been omitted or performed on a different day.

applied to the partner’s CFI-J assessment. As in the original

Tests for which data were not available on the same day as the CFI-

version of the CFI, the 14 questions asking about changes in ADL

J assessment (i.e. four datasets from the MMSE, six datasets fromin the past year were scored on a scale consisting of 1 (yes), 0.5

the CDR, and two datasets from the GDS) were treated as missing(maybe), and 0 (no), and the total score was calculated (range: 0–

data.

14). If a question did not apply (e.g. a person who did not hold adriver’s license was asked about driving), the score for that item

Statistical analysis

was set to zero after confirmation with the author of the original

The median and interquartile range (IQR) of the CFI-J andversion of the CFI.

neuropsychological test scores were calculated for all subjects, andBoth the first self-CFI-J and partner-CFI-J assessments were

they were grouped according to their diagnosis; the groups wereadministered on the same day (time point 1: T1) ascompared using the Mann-Whitney U test. The intra-classneuropsychological tests at the memory clinic (see below), andcorrelation coefficient using a two-way random effects model

the second CFI-J assessment was sent to the subject’s home by(ICC) and 95% confidence interval (CI) were used to evaluate themail four weeks later (time point 2: T2) and returned by mail. In

test-retest reliability of the CFI-J between T1 and T2. To assess

cases where the CFI-J was not returned at T2 for unknown

concurrent validity, the association between CFI-J scores and eachreasons, only the data from T1 were used in the analysis. In

neuropsychological test score was evaluated using the partial rank

addition, for one case in which the person who wrote the partnercorrelation coefficient (Spearman’s rho) with age and sex as

CFI-J at T2 was different from that at T1, only the data from T2adjusted variables. Statistical significance was set at P < .05.

were treated as missing values.

Statistical analyses were performed using SPSS version 27 (IBMCorp., Armonk, NY, USA).

Table 1. Characteristics of the CFI-J respondents
self-CFI-J respondents
Mean age (SD)76.6 (7.9)
Female sex, n (%)
11 (55.0)
Diagnosis, n (%)
CN
6 (30.0)
MCI
14 (70.0)
partner-CFI-J respondents
Mean age (SD)
Female sex, n (%)
Relation, n (%)
SpouseChild
Sibling

Results
Characteristics
Table 1 shows the characteristics of the self-CFI-J and partnerCFI-J respondents. The mean (standard deviation [SD]) age of theself-CFI-J respondents was 76.6 (7.9) years; 11 (55%) subjects
were female, six subjects were diagnosed as cognitively normal(CN), and 14 were diagnosed with MCI. The mean (SD) age
of the partner CFI-J respondents was 64.7 (11.1) years, 15 (75%)

64.7 (11.1)
15 (75.0)

were female, and the relationships of partner to participant included
12 (60.0%) spouses, seven (35.0%) children, and one (5.0%)
sibling. The mean (SD) interval between the two CFI-J assessment

12 (60.0)
7 (35.0)
1 (5.0)

dates was 32.0 (4.2) days.

CFI-J and neuropsychological tests

CFI-J, Cognitive Function Instrument-Japanese version; SD, standard

The CFI-J and neuropsychological test scores are shown in Table

deviation; CN, cognitively normal; MCI, mild cognitive impairment

2. The median (IQR) self CFI-J and partner CFI-J scores at T1 were
4.3 (3.5) and 4.5 (5.5), respectively, and those at T2 were 4.5 (2.0)
and 5.3 (5.5), respectively. The median (IQR) neuropsychological

Neuropsychological tests

test scores were 7.1 (6.7) for the ADAS-Cog, 11.5 (12.0) for the

The results from a set of neuropsychological tests performed as

LM I, 4.5 (13.0) for the LM II, 27.0 (5.0) for the MMSE, 1.8 (1.9)

part of the usual practice in a memory clinic were collected fromfor the CDR-Sum of Boxes (CDR-SB), 14.0 (5.0) for the FAB, andthe medical records. The following assessments were performed:

4.0 (5.0) for the GDS. The CDR-global (CDR-G) score was 0.5.

ADAS-Cog, Logical Memory (LM) I and II of the WMS-R,

There was a significant difference between the CN and MCI

MMSE, clinical dementia rating (CDR), frontal assessment battery-4-Preliminary evaluation of the Japanese version of the Cognitive Function Instrument in a memory clinic

groups in the partner CFI-J assessment (P = .033 at T1; P = .010 at

Test-retest reliability and concurrent validityT2), but not in the self-assessment (P = .968 at T1; P = .579 at T2)

Figure 2 shows the results of plotting the scores at T1 and T2 for(Figure 1). There were also significant differences in thethe self- and partner-CFI-J assessments, respectively. The intra-

neuropsychological test scores between the CN and MCI groups inclass correlation coefficient [95% CI] for the two CFI-J scores,

the ADAS-Cog (P < .001), LM I (P = .012), LM II (P = .003),

which were assessed approximately 4–5 weeks apart, was .442

MMSE (P = .001), and CDR-SB (P = .044) tests, but not in the[.008, .739] (P = .025) for the self- and .811 [.566, .925] (P < .001)

FAB (P = .179) and GDS (P = .143) tests.

for the partner-CFI-J assessments. Although the sample size forboth groups is small, in the CN group, the correlation was
significant only for the self-CFI-J [.892 (.416, .984)], and in the
MCI group, the correlation was significant only for the partnerCFI-J [.782 (.425, 928)].
Both self-CFI-J and partner-CFI-J scores at T1 did not correlatewith any of the neuropsychological tests.

Table 2. Results of the CFI-J and neuropsychological tests
Assessment

n

All

self

20

partner

Diagnosis

P value

n

CN

n

MCI

4.3 (3.5)6

3.5 (5.1)

14

4.5 (3.6)

.968

20

4.5 (5.5)6

2.8 (3.3)

14

5.5 (6.0)

.033

self

19

4.5 (2.0)

6

4.5 (3.6)13

4.5 (2.0).579

partner18

5.3 (5.5)

5

3.0 (1.0)

13

6.0 (6.5).010

ADAS-Cog20

7.1 (6.7)

6

3.4 (3.5)

14

10.4 (5.8)

<.001

LM I

20

11.5 (12.0)

6

21.5 (18.0)

149.5 (8.0)

.012

LM II

20

4.5 (13.0)

6

16.5 (16.0)

140.5 (6.0)

.003

MMSE

16

27.0 (5.0)

4

All 30 (full)

12

26.5 (4.0).001

CDR-SB14

1.8 (1.9)

2

All 0.512

2.0 (2.3)

.044

FAB

20

14.0 (5.0)

616.0 (4.0)

14

13.5 (4.0)

.179

GDS

18

4.0 (5.0)

58.0 (6.0)

13

3.0 (5.0).143

CFI-J (T1)

CFI-J (T2)

Data are presented as median (interquartile range). P

value represents the results of the Mann-

Whitney U test. T1, time point 1 (same day as neuropsychological testing); T2, time point 2(approximately one month after T1); CN, cognitively normal; MCI, mild cognitive impairment; CFI-J,
Cognitive Function Instrument-Japanese version; ADAS-Cog, Alzheimer's Disease Assessment ScaleCognitive Subscale; LM I & II, Logical Memory I & II of the Wechsler Memory Scale-Revised;
MMSE, Mini-Mental Examination; CDR-SB, Clinical Dementia Rating-Sum of Boxes; FAB, Frontal
Assessment Battery; GDS, Geriatric Depression Scale-15.

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Vol.11 No.2, 2021

Figure 1. Box plots of group differences between the CN and MCI groups in the CFI-J scores at each time point.
The whisker boundary shows the 10th percentile (lower) and 90th percentile (upper). The Mann-Whitney U test was used forstatistical analysis. T1, time point 1 (same day as neuropsychological testing); T2, time point 2 (approximately one month after T1);
CN, cognitively normal; MCI, mild cognitive impairment; n.s., not significant.

Figure 2. Intra-class correlation coefficients between T1 and T2 for the CFI-J.
The square plots represent the cognitively normal group, and the circles represent the mild cognitive impairment group. The
reference lines of Y equal to X are shown in each figure. T1, time point 1 (same day as neuropsychological testing); T2, time point
2 (approximately one month after T1); ICC, intraclass correlation coefficient; CI, confidence interval.

-6-Preliminary evaluation of the Japanese version of the Cognitive Function Instrument in a memory clinic

Discussion

assessed it more objectively and reproducibly than the patients

This study has provided certain findings on the properties of thethemselves.

CFI-J that have not been previously investigated. The test-retest

The partner-CFI-J score was significantly higher in the MCI

reliability of the CFI-J was found for both self and partnergroup than in the CN group and was considered to adequately

assessments, and the partner-CFI-J score adequately represented

reflect the decline in ADL ability due to minor cognitive decline.

the subject’s status (CN or MCI). By contrast, concurrent validity

Previous studies have shown that CFI scores for both self andwith the neuropsychological tests used in the memory clinic waspartner assessments were higher in the MCI group than in the CN

not found for either the self-CFI-J or partner-CFI-J assessments.

group6), and higher in the CDR-G 0.5 group than in the CDR-G 0

The ICC point estimate of .442 for the two self-CFI-J scores ingroup10). For the partner-CFI-J, the results were similar to those of

the present study is considered to indicate moderate test-retest

these previous studies and were considered to have some validity,

9)

reliability, referring to the criteria given by Landis et al .

but in respect of the self-CFI-J results, we were not able to confirm

According to a previous study of the ADCS10), the ICC [95% CI]such inter-group differences. It has been suggested that the self-CFIof the self-CFI assessment at 3-month intervals was reported toand partner-CFI may differ in the accuracy with which they reflect

be .75 [.69, .80] in 497 subjects with a CDR-G score of 0 and .72

the abilities of the subjects, depending on the target population.

[.59, .81] in 147 subjects with a CDR-G score of 0.5. AnotherSpecifically, it has been reported that in the CDR-G 0 group, theprevious study of the ADCS reported an ICC of .73 for the self-

self-CFI and partner-CFI scores at baseline and the change in

CFI assessment at 12-month intervals in 209 subjects, all ofscores after two years were predictive of the change in the subject’s

whom had a stable CDR-G of 0 and were APOE ε4 non-carriers,

cognitive function after two years, but in the CDR-G 0.5 group,5)

during four years of observation . Compared to these data, theonly the change in the partner-CFI-J score was predictive10). In

ICC of the self-CFI-J in this study was considered to be slightly

addition, in a previous study that examined whether dementia andlower. This may be related to the fact that the study was

MCI could be discriminated by receiver operating characteristic

conducted only on outpatients in the memory clinic. According to(ROC) analysis, the AUCs [95% CI] of the self-CFI and partner-a previous longitudinal study of community-dwelling elderly

CFI were .58 [.48, .67] and .79 [.70, 88], respectively, and it was

subjects with a CDR-G of 0 at baseline, CDR-G progressors

reported that only the partner CFI showed significant(from 0 to 0.5, or higher) already showed an increasing trend in

discriminatory performance6). It is well known that MCI and AD

the self-CFI scores three months after baseline5). Generally, inare associated with impaired functioning of the dorsolateralJapan, the reason why a person with CN or MCI would visit an

prefrontal cortex (DLPFC), a central neural basis for working

outpatient memory clinic is often due to the presence of a greater

memory and executive function, and a recent study using macaquethan normal decline (subjective or objective) in cognitive andmonkeys has shown that the DLPFC is specifically involved in the

ADL function and the need for specialised monitoring of theseability to reflectively monitor past experiences11). In this study, 14changes. Therefore, the self-CFI-J scores in this study were higher

out of 20 subjects were diagnosed with MCI, and 10 (71.4%)

for more participants in the second experiment than in the firstscored less than 4 points on the LM II. The results suggest that byexperiment (Figure 2), which may have resulted in a moderateusing self-administered questionnaires in subjects with MCI who

ICC. The partner CFI-J assessment showed sufficient agreement

have obvious memory impairments, it may be difficult to detect a9)(‘almost perfect’ according to the criteria by Landis et al. ,decline in ADL ability that is associated with minor cognitive

confirming the test-retest reliability at intervals of approximately

decline.

one month. Additionally, the fact that this study was conducted in

There was no correlation between the CFI-J scores anda clinical setting may explain why the ICC of the partner CFI-J

neuropsychological test scores in this study, suggesting that thewas higher than that of the self-CFI-J. In addition to the patient's

CFI-J should be used with caution as a cross-sectional screening

own factors of instability in cognitive functioning andtool for cognitive function in memory clinics. This result differs

psychological state, the characteristics of the family members whofrom previous studies5,7), and unfortunately, the reasons for thisaccompany the patient to the clinic may also play a role. The

difference are unclear. A previous study of the Japanese version ofpatient is usually accompanied to the memory clinic by someone

the Everyday Memory Checklist (EMC)12,13), a self-administered

who is familiar with the patient's usual living situation. The CFI

questionnaire specific to memory impairment, in patients with mild

question "Compared to one year ago..." may have resulted in a

AD, reported that the correlation with the LM II score was foundhigher ICC, as the family members or attendants could have

only with EMCs rated by family caregivers and not with patient
self-ratings. The results of the self-CFI-J may have been influenced-7-一般社団法人

日本認知症予防学会誌
Vol.11 No.2, 2021

Referencesby the inclusion of subjects with obvious memory deficits, but it1)Alzheimer's Association. (2020). Alzheimer's disease facts andfigures. Alzheimers Dement 16(3): 391-460.
2)Ngandu T, Lehtisalo J, Solomon A et al. (2015). A 2 year
multidomain intervention of diet, exercise, cognitive training,and vascular risk monitoring versus control to prevent cognitive
decline in at-risk elderly people (FINGER): a randomised
controlled trial. Lancet 385(9984): 2255-2263.
3)Weiner MW, Veitch DP, Aisen PS et al. (2017). The Alzheimer's
Disease Neuroimaging Initiative 3: Continued innovation forclinical trial improvement. Alzheimers Dement 13(5): 561-571.
4)Mitchell AJ. (2009). A meta-analysis of the accuracy of the minimental state examination in the detection of dementia and mild
cognitive impairment. J Psychiatr Res 43(4): 411-431.
5)Amariglio RE, Donohue MC, Marshall GA et al. (2015).
Tracking early decline in cognitive function in older individuals
at risk for Alzheimer disease dementia: the Alzheimer's Disease
Cooperative Study Cognitive Function Instrument. JAMA
Neurol 72(4): 446-454.
6)Michelet M, Engedal K, Selbaek G et al. (2018). The Validity of
the Norwegian Version of the Cognitive Function Instrument.
Dement Geriatr Cogn Disord 46(3-4): 217-228.
7)Chipi E, Frattini G, Eusebi P et al. (2018). The Italian version of
cognitive function instrument (CFI): reliability and validity in acohort of healthy elderly. Neurol Sci 39(1): 111-118.
8)Walsh SP, Raman R, Jones KB Aisen PS, Alzheimer's Disease
Cooperative Study G. (2006). ADCS Prevention Instrument
Project: the Mail-In Cognitive Function Screening Instrument(MCFSI). Alzheimer Dis Assoc Disord 20(4 Suppl 3): S170178.
9)Landis JR, Koch GG. (1977). The measurement of observer
agreement for categorical data. Biometrics 33(1): 159-174.
10)Li C, Neugroschl J, Luo X et al. (2017). The Utility of the
Cognitive Function Instrument (CFI) to Detect Cognitive
Decline in Non-Demented Older Adults. J Alzheimers Dis
60(2): 427-437.
11)Miyamoto K, Osada T, Setsuie R et al. (2017). Causal neuralnetwork of metamemory for retrospection in primates. Science355(6321): 188-193.
12)Wilson B, Cockburn J, Baddeley A, Hiorns R. (1989). The
development and validation of a test battery for detecting andmonitoring everyday memory problems. J Clin Exp
Neuropsychol 11(6): 855-870.
13)Kazui H, Hirono N, Hashimoto M et al. (2006). Symptoms
underlying unawareness of memory impairment in patients withmild Alzheimer's disease. J Geriatr Psychiatry Neurol 19(1): 312.
14)Bonett D. (2002). Sample size requirements for estimating
intraclass correlations with desired precision. Stat Med 21(9):1331-1335.

was difficult to fully discuss the results of the partner-CFI-J.
The present study had several limitations. The first is the effect ofa small sample size. According to Bonnet14), approximately 100
subjects are needed to estimate an ICC [95% CI] of
approximately .7 [.6, .8]. The confidence intervals for the ICCs of
the self-CFI-J in this study are very wide, and further subject
aggregation is needed for a more accurate analysis. For correlation
analysis with neuropsychological test scores, a number of subjects
less than 200 would be required to estimate a Spearman's rankcorrelation coefficient of approximately .2 with a statistical powerof 0.8, comparable to previous studies7). The lack of correlation
between the CFI-J and neuropsychological tests could be the resultof a statistical type II error. Second, as mentioned several times inthis discussion section, the demographics of the study population
are very limited; therefore, caution should be exercised whengeneralising the results of this study to people of otherdemographics. Finally, although this study focused only on the
CFI-J at a single point in time, previous studies have used not only
the score at a single point in time, but also the amount of change
from baseline to months or years later as a measure.
In this study, partly because of the aforementioned limitations, we
could not completely prove the retest reliability of the self-CFI-J,
nor could we confirm the concurrent validity of the CFI-J.
Nevertheless, because it can be conducted easily, the CFI-J is anappropriate measure for the early identification of high-risk
individuals with dementia in community health check-ups andlarge-scale surveys, although, further studies are needed. Some ofour members are currently conducting the CFI-J assessments incognitively normal elderly people living in the community as partof another research project to observe changes in the CFI-J andcognitive function over time. It is envisaged that the CFI-J will bevalidated as an assessment method to detect minor cognitive
decline in elderly people with normal cognitive function andextensively used following revisions and other developments.

Acknowledgements
We are grateful for the permission from the NIA-funded
Alzheimer's Disease Cooperative Study (NIA Grant U19
AG10483) to use the CFI, and to Dr. Ryoma Kayano of the World
Health Organization Centre for Health Development (WHO Kobe
Centre) for his invaluable assistance in contacting ADCS for
permission to use and translate the CFI. We also thank Miyuki
Kawabata and Ayumi Okada for their research management.

Disclosure statement
The authors have no potential conflicts of interest to disclose.

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