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 (United
Nations, 2009). 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 (Reid and MacLullich, 2006).
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.