Briefing paper

The road to reducing dementia onset and prevalence: are diet and physical activity interventions worth investing in?

3 Jul 2015

In Australia, deaths as a result of dementia have now taken over cerebrovascular disease as the second leading cause of death. At present, over a quarter million Australians suffer from dementia and projected estimates indicate that the figure can reach a high of nearly one million by 2050.

Diet and physical activity have been shown to promote brain health and offer some protection against cognitive decline. Moreover, they have also been recognised as risk factors for developing other conditions such as cardiovascular disease, diabetes, hypertensive diseases and certain cancers all of which are leading causes of death in Australia.

Research shows that higher ratios of saturated fat to monounsaturated fats are predictive of negative mental function. In addition, high mid-life serum cholesterol levels and excessive caloric intake have been found to be associated with impaired cognitive function. Increased intakes of fish, vegetables and legumes, antioxidant rich foods and adequate amounts of certain B-vitamins have been reported to have a protective brain effect.

Increased levels of physical activity have been found to promote neuro-protective changes in the hippocampus of the brain – a region central to learning and memory. This brain region is one of the first areas affected by dementia. Most studies have demonstrated that a high level of physical activity in adults with no dementia is associated with a 30% to 50% reduction in the risk of cognitive decline and dementia. Some studies have also theorised that poor physical function may precede the onset of dementia and Alzheimer’s disease and higher levels of physical function may be associated with delayed onset. Results from the Australian Bureau of Statistics National Health Survey (2011 – 2013) show that many Australian adults do not meet the National Physical Activity Guidelines (to do at least 30 minutes of moderate intensity physical activity on most days) as more than half the population is inactive. Further, two-thirds of Australians are now overweight/obese and a large proportion of total energy consumed comes from foods considered to be of little nutritional value. An intervention that focuses on improving diet and physical activity habits therefore has the ability to produce inestimable benefits.

There are many factors that must be considered when developing a successful diet and physical activity intervention. These span a gamut of issues from carefully defining the target audience, utilising a multidisciplinary approach, tailoring content and materials, determining forms of delivery and identifying specific behaviour change techniques to determining financial costs in relation to health benefits and training staff. The success of any intervention also relies on the setting and method that will be employed in its implementation.

Policy-makers must be cognizant of the fact that no singular government intervention/policy, operating on its own, can have the effect of directly reducing dementia onset/prevalence and changing lifestyle habits. Six actions for policy-makers are identified in this issues brief which have the potential to have immeasurable benefits: i) development of a comprehensive dementia prevention strategy, ii) establishment of a body whose aim is to keep track of scientific research (central to this will be the establishment of a national digital dementia research repository), iii) ensuring a multisectoral approach is adopted in the fight against dementia that includes both ‘traditional’ and ‘incidental’ health agencies, iv) continued investment into research and innovation, v) identifying incentives beyond the health domain and vi) development of longevity literacy programs. These actions all have as their foundation the Health in all Policies Initiative and social determinants of health approach.

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