Vitamin A and Alzheimer's disease

The deposition of amyloid β‐protein (Aβ) in the brain is an invariant feature of Alzheimer's disease (AD). Vitamin A, which has been traditionally considered an anti‐oxidant compound, plays a role in maintaining higher function in the central nervous system. Plasma or cerebrospinal fluid concentrations of vitamin A and β‐carotene have been reported to be lower in AD patients, and these vitamins have been clinically shown to slow the progression of dementia. Vitamin A (retinol, retinal and retinoic acid) and β‐carotene have been shown in in vitro studies to inhibit the formation, extension and destabilizing effects of β‐amyloid fibrils. Recently, the inhibition of the oligomerization of Aβ has been suggested as a possible therapeutic target for the treatment of AD. We have recently shown the inhibitory effects of vitamin A and β‐carotene on the oligomerization of Aβ40 and Aβ42 in vitro. In previous in vivo studies, intraperitoneal injections of vitamin A decreased brain Aβ deposition and tau phosphorylation in transgenic mouse models of AD, attenuated neuronal degeneration, and improved spatial learning and memory. Thus, vitamin A and β‐carotene could be key molecules for the prevention and therapy of AD. Geriatr Gerontol Int 2012; 12: 180–188.