Archief Roodbont

Vitamin D deficiency is associated with several chronic illnesses, but studies of its association with cognitive function have been short and have yielded equivocal results. Data from the well-known InCHIANTI study of older Italian people (J Am Geriatr Soc 2000; 48:1618) were used to determine the relation between cognitive decline among 858 participants (mean age at baseline, 74) and baseline levels of 25-hydroxyvitamin D (25[OH]D). 25(OH)D levels were classified as severely deficient (<10 alt="≥">30 ng/mL [75 nmol/L]). Patients were assessed at baseline and every 3 years with several cognitive tests, including the Mini-Mental State Examination (MMSE).

At 6 years, analyses that were adjusted for clinical factors relevant to cognitive functions and for impaired mobility showed that participants with severe deficiency were 60% more likely to experience significant declines of 3 points on the MMSE than were participants with sufficient levels of 25(OH)D. Similar relative risks were noted for most secondary measures of cognition.

Comment: Despite appropriate adjustment, these results still could reflect reverse association — i.e., frail patients who are inactive and sun-deprived would have lower levels of 25(OH)D. Editorialists suggest that we move past observational studies and design prospective trials to assess the risks and benefits of vitamin D supplementation specifically.

— Thomas L. Schwenk, MD

Published in Journal Watch General Medicine July 27, 2010