The effects of Vitamin D Insufficiency and Seasonal Decrease on cognition.

Area of Science:

• Neuroscience
• Endocrinology
• Public Health

Background:

• Vitamin D3 (cholecalciferol) deficiency is a potential risk factor for dementia and cognitive decline.
• The specific cognitive domains affected by Vitamin D3 levels and the impact of seasonal variations remain unclear.

Purpose of the Study:

• To investigate the association between Vitamin D3 levels and cognitive function in adults at northern latitudes (54°N).
• To examine how seasonal fluctuations in Vitamin D3 impact cognitive performance.

Main Methods:

• A prospective observational study involving healthy adults tested in summer and winter.
• Cognitive assessments included the Symbol Digit Modalities Test, phonemic fluency, digit Span, and the CANTAB battery.
• Vitamin D3 levels were measured in both summer and winter.

Main Results:

• In summer, Vitamin D3 insufficiency (<75 nmol/L) was associated with worse performance on the Digit Span Backward task (p=0.018).
• In winter, a majority of participants were insufficient, with levels declining by a median of 15 nmol/L.
• Vitamin D3 insufficiency and significant seasonal declines (≥15 nmol/L) correlated with impaired performance on working memory and executive functioning tasks (CANTAB SWM and OTS).

Conclusions:

• Vitamin D3 insufficiency and seasonal drops are linked to deficits in working memory and executive functions.
• Maintaining adequate Vitamin D3 levels throughout the year is suggested, particularly for those at higher latitudes.
• Supplementation may be necessary during winter months to ensure sufficient Vitamin D3 levels and support cognitive health.