Serum vitamin D deficiency as a predictor of incident non-Alzheimer dementias: a 7-year longitudinal study.

BACKGROUND: Hypovitaminosis D has been cross-sectionally associated with dementia and stroke. The objective of this longitudinal study was to determine whether serum vitamin D deficiency at baseline could predict the onset of non-Alzheimer dementias (NAD) within 7 years among older women.

METHODS: Forty high-functioning older women (78.4 years, 76.4/82.0; median, 25th/75th percentile) from the EPIDOS Toulouse study were divided into two groups based on vitamin D deficiency (i.e., serum 25-hydroxyvitamin D <10 ng/ml) at baseline. At the end of the 7-year follow-up period, women matching the DSM-IV but not the NINCDS-ADRDA criteria were diagnosed with NAD while those matching the NINCDS-ADRDA criteria were considered to have Alzheimer's disease (AD). Subtle cognitive impairments at baseline, cardiovascular risk factors and Parkinson's disease were used as potential confounders.

RESULTS: NAD was reported in 6 women (82.8 years, 80.6/86.0) after 7 years of follow-up. More NAD were observed in women with vitamin D deficiency (p = 0.023). There was no between-group difference regarding the onset of AD (p = 0.332). We found an association between vitamin D deficiency at baseline and the onset of NAD (adjusted odds ratio = 19.57, p = 0.042). Conversely, vitamin D deficiency was not associated with AD (p = 0.222).

CONCLUSION: Baseline vitamin D deficiency predicted the onset of NAD within 7 years among older women.