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 deficiency was associated with poorer mental flexibility among older community dwellers with memory complaint.