Hypovitaminosis D and Executive Dysfunction in Older Adults with Memory Complaint: A Memory Clinic-Based Study

Abstract

Background: Hypovitaminosis D is associated with executive dysfunction as a whole. The purpose of this cross-sectional study was to determine whether lower vitamin D levels were associated with mental flexibility, information updating, or cognitive and motor inhibition among older adults. Methods: One hundred Caucasian older community dwellers with memory complaint (mean, 71.02 ± 0.74 years; 52.0% female) were divided into 3 groups according to serum 25-hydroxyvitamin D (25-OHD) concentration (deficiency <25 nmol/l, insufficiency 25-50 nmol/l, sufficiency >50 nmol/l). Executive functions were assessed with error rates by executing the Trail Making Test-B (TMT-B) for mental flexibility, the N-Back Test for information updating, the Stroop Interference Test for cognitive inhibition, and the Go/No-Go score for motor inhibition. Age, gender, BMI, education level, number of morbidities, depressive symptoms, Mini-Mental State Examination score, calcemia, estimated glomerular filtration rate and season tested were considered as potential confounders. Results: Compared to participants with vitamin D insufficiency and sufficiency, those with vitamin D deficiency had a poorer TMT-B performance (p = 0.019 and p = 0.017, respectively) but similar N-Back (p = 0.175), Stroop (p = 0.135) and Go/No-Go (p = 0.224) scores. Cognitive performance did not differ between participants with insufficient and sufficient vitamin D levels. Vitamin D deficiency was associated with poorer performance on TMT-B (adjusted β = 1.48, p = 0.011), but not on N-Back (p = 0.665), Stroop (p = 0.817) or Go/No-Go (p = 0.971). Conclusion: Vitamin D deficiencywas associated with poorer mental flexibility among older community dwellers with memory complaint.

Vitamin D status is associated with executive function a decade later: Data from the Women’s Healthy Ageing Project

“…In this study, when examining the relationship observed using various vitamin D cut-off points, we found a relationship only at the lower level of vitamin D deficiency (≤ 25nmol/L), with no differences at insufficient or suboptimal (50nmol/L or 75nmol/L) levels. Consistent with previous work, these findings suggest that the clinical effects of vitamin D are nonlinear [19], and are more apparent at the severe levels of vitamin D deficiency [20] compared with insufficiency [21]. Certainly, findings have also shown that higher levels of vitamin D produce unfavorable effects on verbal episodic memory performance [22], providing important insight that repletion may only yield significant clinical benefits in severely deficient individuals.…”

A Systematic Review and Meta‐Analysis of The Effect of Low Vitamin D on Cognition

“…5,7,8,16,27,[36][37][38][39][40][41] Eight studies reported vitamin D as a continuous variable, 5,6,10,27,29,36,39,42 27 as a categorical variable, and three reported both. Seventeen studies used a-priori cut offs 6,8,[14][15][16]28,34,35,37,41,[43][44][45][46][47][48][49] and 13 categorized into tertiles, 9,17,38,50,51 quartiles, 7,12,18,33 or quintiles. 13,40,52,53 The majority of studies analyzed serum 25OHD with four analyzing plasma 25OHD.…”

“…Stroop color-word, 9,42,44,50 Digit Symbol Coding, 7,15,47,49 finger tapping, 7 Symbol Digit Modalities Test, 8,9,46 Trail Making Test A 9,11,27,34,42,47,49 and B, 9,11,18,27,29,33,34,42,44,47,49 Best Symbol-Digit Substitution Test, 16,17,27,28,34,36,39,40,42 serial reaction time, 32,40,42,50 choice reaction time, 30,42 switch-cost reaction time, 32 letter cancelation, 14 Go-no-Go. 44…”

Serum 25-Hydroxyvitamin D and Cognitive Decline: A Longitudinal Study among Non-Demented Older Adults

“…Among women and men receiving home services, low levels of 25(OH)D were associated with dementia and cerebrovascular pathology [9], and among older patients at a memory clinic, hypovitaminosis D was associated with executive dysfunction [10]. Meta-analyses and systematic reviews of epidemiological studies also seem to suggest that low serum concentrations of 25(OH)D are associated with cognitive impairment and an increased risk of dementia [11,12,13,14].…”