The effects of chronic multivitamin supplementation on neurocognition in the elderly

Age-related decline occurs across the lifespan and is a feature of the normal ageing process. With an ageing global population there is an increasing scientific interest in the potential of health and lifestyle interventions to improve cognitive function in the elderly. Evidence from epidemiological and randomised controlled trials has indicated that vitamins and other dietary substances may be particularly important for cognitive function. Heterogeneous findings have been obtained from Randomised Controlled Trials which have investigated the effects of multivitamin supplements on cognition, in older adults. This study represents the first trial to apply neuroimaging techniques to investigate the effects of multivitamin supplementation on brain electrical activity. When combined with behavioural measures the examination of brain electrical activity may provide additional insights into the neurocognitive effects of chronic multivitamin supplementation. This thesis reports the findings from a 16 week, randomised, placebo-controlled, double-blind trial which investigated the effects of chronic multivitamin supplementation on cognitive performance and the steady state visually evoked potential (SSVEP) measure of brain electrical activity, shown previously to be sensitive to fast occurring changes in cognition. The multivitamin contained a combination of vitamin, mineral and herbal components. Participants were elderly women aged between 64 and 82 years. 28 participants were allocated to the multivitamin treatment and 28 to placebo. Cognitive performance was assessed using a validated battery of computerised memory and attentional tasks. It was predicted that chronic treatment with a combined multivitamin and herbal supplement would enhance the cognitive domains most vulnerable to age-related decline. Changes in the SSVEP were assessed during the performance of a spatial working memory delayed response task. Biochemical and cardiovascular mechanisms of potential cognitive enhancements were also examined. The results indicated that multivitamin supplementation improved spatial working memory speed of response, a cognitive process which is known to be compromised with age. There were no multivitamin-related treatment effects for measures of attention or verbal memory. Multivitamin supplementation significantly increased SSVEP latency, interpreted as an increase in inhibitory neural processes. The multivitamin increased concentrations of vitamin B6, B12, E and lowered homocysteine. Multivitamin supplementation did not benefit other measures of cardiovascular health, indicating the observed cognitive improvements were not mediated by cardiovascular mechanisms. Findings from this study indicate that the SSVEP measure of brain activity is useful for examining the neurocognitive effects of multivitamins. Furthermore, it is suggested that chronic multivitamin supplementation may be effective to improve neurocognition in the elderly.