The world's population is aging rapidly, with the proportion of the population over 60 growing at a rate of around 2% per annum in the developed world. In the most developed regions, 264 million people (21% of the population) were estimated to be 60 years and older in 2009, with this figure projected to increase to around 416 million (33% of the population) by the year 2050 (United Nations, 2009). A major societal health issue for an aging population is not only the greater incidence of neurodegenerative disorders such as Alzheimer's disease but also the impact of normal age-related cognitive decline. Up to 50% of adults aged 64 and over have reported difficulties with their memory. In response to the reality of an aging population, there has been increased research focus in recent years on the development of effective interventions that may ameliorate the declines in cognitive ability. Age-related reductions in the brain's gray matter are due to a number of factors including neuron apoptosis, neuron shrinkage, and lowered numbers of synapses; whereas reductions in white matter may be attributed in part to large age-related decreases in the length of myelinated axons. During aging the brain suffers accumulative damage due to a number of cellular processes including reactive oxygen species formation, chronic inflammation, redox metal accumulation, and homocysteine accumulation. In addition to direct cellular damage, the brain is also indirectly impaired by insults to the cardiovascular system. While the unfortunate decline in cognitive ability is ubiquitous, it is also evident that a great deal of variability exists in both the rate and the extent of cognitive decline experienced by individuals as they age. While some of the variance may be explained by genetic factors, there is also a great deal of research highlighting the importance of diet and lifestyle during aging. Chronic nutraceutical interventions hold great promise in ameliorating age-related cognitive decline because they simultaneously target multiple cellular mechanisms of cognitive decline. Many natural substances already identified through in vivo as well as clinical studies have been found to have potent anti-oxidant and anti-inflammatory properties as well as being of benefit to the cardiovascular system. In order to be able to accurately assess and interpret the clinical efficacy of these natural substances, it is recommended in the following review that highly accurate and specific cognitive tests are needed, together with the creation of normative databases that may be used to interpret clinical data in terms of years of cognitive function recovered.
Advances in natural medicines, nutraceuticals and neurocognition / Con Stough and Andrew Scholey (eds.), Chapter 2, pp. 17-28
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