Plasma PLP Concentration and Depressive Symptomatology in older Latino Adults: A Longitudinal Analysis with time‐varying Covariates
Authors: Arevalo Sandra P , Scott Tammy E , Falcon Luis M , Tucker Katherine L 
Published: November 2023

BackgroundLow vitamin B‐6 status has been linked to depressive symptomatology. However, most studies have been cross‐sectional and may not have controlled for relevant confounders. Few studies have examined this association in Latino populations at high risk for major depression.ObjectiveOur objective was to examine the longitudinal association of vitamin B‐6 status with depressive symptomatology in a cohort of older Puerto Rican adults, a population previously identified to be at high risk for depressive symptomatology and clinical depression.ResultsIn two level hierarchical linear regression models that account for the clustering of measures of participant's depressive symptomatology (Level‐1) at three different points in time nested within participants (Level‐2); plasma pyridoxyl‐5′‐phosphate (PLP) concentration, a time‐varying predictor, was significantly associated with higher depressive symptomatology over the three time points. This negative association persisted after adjusting for body mass index (BMI), level of physical activity, smoking, alcohol use, hypertension, diabetes, time‐varying vitamins B‐12, folate and D; and baseline dietary intake of magnesium, allostatic load (physiological stress), stressful life events (social stress) and perceived stress (psychological stress), plasma homocysteine concentration (tHCY), and use of antidepressant medication. The slope of the decline in depressive symptomatology over time was steeper in participants with PLP>30 nmol/L vs. participants with suboptimal PLP plasma concentration; however, this difference was not statistically significant.ConclusionsWe found significantly higher depressive symptoms in participants with suboptimal plasma PLP compared to participants with adequate PLP concentration over three time points. Findings from our study highlight the need to adjust for physiological, psychological and social stress when examining the effect of micro‐nutrients on depressive symptoms. Our data suggest that identification and treatment of vitamin B‐6 deficiency may be a useful preventive and intervention approach in older Puerto Rican adults, and potentially other Hispanic subgroups.Support or Funding InformationThis study was funded by the National Heart, Lung, and Blood Institute; National Institutes of Health (Grant 5P50HL105185, Katherine L. Tucker, PhD, Principal Investigator)
Longitudinal Associations between Depressive symptomatology (CES‐D) and time‐varying suboptimal PLP status in the Puerto Rican Health study participants

Model 1a
Model 2b
Model 3c
Model 4d
Model 5e
Model 6f

β
(SE)
p‐value
β
(SE)
p‐value
β
(SE)
p‐value
β
(SE)
p‐value
β
(SE)
p‐value
β
(SE)
p‐value

Suboptimal Vitamin B‐6 (plasma PLP<30 nmol/L)

No use ‐ref

‐

‐

‐

‐

‐

‐

Yes
0.68
0.56
0.23
0.57
0.56
0.31
0.52
0.57
0.36
0.34
0.65
0.60
1.16
0.57
0.04
1.06
0.57
0.06

Time
−0.47
0.10
< 0.0001
−0.72
0.10
<0.0001
−0.42
0.10
<0.0001
−0.44
0.11
<0.0001
−0.64
0.11
<0.0001
−0.66
0.11
<0.0001

Suboptimal Vitamin B‐6 * Time

No use ‐ref

‐

‐

‐

‐

‐

‐

Yes
0.23
0.19
0.24
0.15
0.19
0.43
0.17
0.20
0.39
0.11
0.22
0.62
0.09
0.23
0.68
0.11
0.22
0.64

Goodness of fit

N
12
15
17
21
24
26

df
3016
2985
2933
2350
2187
2187

Log Likelihood
−11537.92
−11394.91
−11198.46
−9008.93
−8011.75
−7996.55

AIC
23099.84
22819.83
22430.92
18059.85
16071.51
16045.09

BIC
23171.98
22909.85
22532.65
18180.86
16208.08
16193.04

Model 1: age + sex + education + BMI
Model 2: Model 1 + smoking + alcohol use + physical activity
Model 3: Model 2 + hypertension + diabetes
Model 4: Model 3 + time‐varying plasma vitamins (B‐12, Folate, D) + baseline energy adjusted magnesium diet intake
Model 5: Model 4 + allostatic load + stressful life events + perceived stress
Model 6: Model 5 + tHCY + antidepressant drug use