Many findings arising from experimental studies, mostly using in vitro or animal models, seem to indicate that vitamin D plays a role in nervous system physiology and physiopathology with the potential for also determining the pathogenesis of certain degenerative diseases, such as dementia. It appears that vitamin D exerts neurotrophic, neuroprotective and neuroplastic effects, whilst also being involved in the synthesis of certain neurotransmitters. Data drawn from prospective observational studies have clearly confirmed the experimental observations by showing an inverse association between vitamin D status (25-hydroxyvitamin D concentration) and the incidence of dementia, with a dose-response relationship. To date, interventional studies using cholecalciferol to reduce the risk of dementia have not had positive results. This has been mainly due to significant limitations in terms of experimental design, treatment regimens, test population size and follow-up duration. Ad hoc and methodologically more appropriate study designs are needed to define the potential beneficial effect of cholecalciferol in preventing the risk of dementia.
