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Vitamin D and cognitive function and dementia risk in a biracial cohort: the ARIC B rain MRI Study
Author(s) -
Schneider A. L. C.,
Lutsey P. L.,
Alonso A.,
Gottesman R. F.,
Sharrett A. R.,
Carson K. A.,
Gross M.,
Post W. S.,
Knopman D. S.,
Mosley T. H.,
Michos E. D.
Publication year - 2014
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1111/ene.12460
Subject(s) - medicine , hazard ratio , digit symbol substitution test , dementia , confidence interval , cohort , vitamin d and neurology , prospective cohort study , cognitive decline , cognition , odds ratio , demography , psychiatry , pathology , disease , alternative medicine , sociology , placebo
Background and purpose Some recent studies in older, largely white populations suggest that vitamin D, measured by 25‐hydroxyvitamin D [25( OH )D], is important for cognition, but such results may be affected by reverse causation. Measuring 25( OH )D in late middle age before poor cognition affects behavior may provide clearer results. Methods This was a prospective cohort analysis of 1652 participants (52% white, 48% black) in the A therosclerosis R isk in C ommunities ( ARIC ) B rain MRI Study. 25( OH )D was measured from serum collected in 1993–1995. Cognition was measured by the delayed word recall test ( DWRT ), the digit symbol substitution test ( DSST ) and the word fluency test ( WFT ). Dementia hospitalization was defined by ICD ‐9 codes. Adjusted linear, logistic and C ox proportional hazards models were used. Results Mean age of participants was 62 years and 60% were female. Mean 25( OH )D was higher in whites than blacks (25.5 vs. 17.3 ng/ml, P < 0.001). Lower 25( OH )D was not associated with lower baseline scores or with greater DWRT , DSST or WFT decline over a median of 3 or 10 years of follow‐up ( P > 0.05). Over a median of 16.6 years, there were 145 incident hospitalized dementia cases. Although not statistically significant, lower levels of 25( OH )D were suggestive of an association with increased dementia risk [hazard ratio for lowest versus highest race‐specific tertile: whites 1.32 (95% confidence interval 0.69, 2.55); blacks 1.53 (95% confidence interval 0.84, 2.79)]. Conclusions In contrast to prior studies performed in older white populations, our study of late middle age white and black participants did not find significant associations between lower levels of 25( OH )D with lower cognitive test scores at baseline, change in scores over time or dementia risk.