Vitamin D and ageing: neurological issues.

OBJECTIVE Vitamin D has been shown to have multiple biological targets mediated by the vitamin D receptor present in many cells. Specific actions on the central nervous system (CNS) have been described. The objective of this review was to describe the relationship between vitamin D and the nervous system throughout the different stages of life. METHODS A bibliographical search was performed in the MedLine and Cochrane library databases. The keywords used were: 'vitamin D' and 'nervous system' and/or 'central nervous system' and/or 'nervous system diseases' and/or 'psychological tests' and/or 'neuropsychological tests' and/or 'mental disorders'. The search period ranged from 01/01/1988 to 31/10/2009. Two hundred and ninety-five abstracts were first identified after screening. A final selection of 127 articles was used for the purpose of this review. RESULTS The studies published over the past 20 years provide an increasing number of arguments in favor of a life-long role of vitamin D on the nervous system as a whole, and in particular on the CNS. During cerebral development, vitamin D may act like a neurosteroid hormone in the areas of neurotransmission, neuroprotection, and neuroimmunomodulation. Moreover, vitamin D deficiency has been associated with neurological and psychiatric disorders. In older adults, hypovitaminosis D has been associated with neuromuscular disorders, dementia, and Parkinson's disease. Thus, vitamin D supplementation might have a protective effect against these neurological disorders. CONCLUSIONS Vitamin D has been associated with many neurological functions and its deficiency with dysfunction. Low serum 25-hydroxyvitamin D concentrations can potentially be reversed. This simple and low-cost correction might contribute to the primo-secondary prevention of various neuropsychiatric disorders.