Dementia, Alzheimer’s disease and depression are all topics that I have written about frequently. I am highly interested in the ways that nutrition and lifestyle can impact the risk of developing such conditions and how, potentially, diet and lifestyle may be used in prevention strategies. In particular I have concentrated on Omega 3 fats and depression and the importance of omega 3 fatty acids for health in general.
A recent study has been published in the British Journal of Medicine (1,2) which has found that eliminating diabetes and depression, as well as increasing education and fruit and vegetable consumption, are likely to have the biggest impact on reducing levels of dementia in the coming years, should no effective treatment be found.
Multiple potentially modifiable clinical and environmental risk factors for dementia have been identified from previous studies e.g. heart disease, stroke, high blood pressure, obesity, diabetes, and high cholesterol, a history of depression, diet, alcohol consumption, and education level. Based on this knowledge the researchers of this study estimated which of risk factors might be most effective in reducing the future burden of dementia (1,2).
The study included over 1,400 healthy individuals aged over 65 years old who were living in the south of France and recruited between 1999 and 2001. The study participants were evaluated with cognitive testing at the start of the study and again at two, four and seven years. A specific reading test (known as the Neale score) was also used as an indicator of lifetime intelligence. Other data was also obtained such as medical history, height, weight, education level, monthly income, mobility, dietary habits, alcohol consumption, and tobacco use. The individual’s genetic risk of dementia was also measured, this measure is obviously not a factor that can be changed however, it serves as a useful benchmark for dementia risk (1,2).
Analysis of the data revealed that eliminating depression and diabetes and increasing fruit and vegetable consumption were estimated to lead to an overall 21% reduction in new cases of dementia, with depression making the greatest contribution (just over 10%). The researchers point out that this is just an association and the direct, causal, relationship between depression and dementia remains unclear. Further studies would be needed to draw more definite conclusions. It was also found that increasing education could lead to an estimated 18% reduction in new cases of dementia across the general population over seven years. By contrast, eliminating the foremost known genetic risk factor from the general population would lead only to a 7% reduction in the number of new cases over the next seven years (1,2).
After elucidating these findings the study researchers suggest that public health initiatives could aim to focus on:
*Encouraging literacy at all ages irrespective of ability,
*Prompt treatment of depressive symptoms,
*Early screening for glucose intolerance and insulin resistance (early stages in the development of diabetes).
The researchers conclude that “In the face of a pandemic of dementia, with predicted increases of 100% in developed countries between 2001 and 2020, and of 300% in China, India, and neighbouring south Asian and western Pacific countries, even small reductions in incidence, or delaying the age of onset, are likely to have significant effects on prevalence and the enormous associated public health burden”. “Increasing crystallised intelligence and fruit and vegetable consumption and eliminating depression and diabetes are likely to have the biggest impact on reducing the incidence of dementia, outweighing even the effect of removing the principal known genetic risk factor. Although causal relations cannot be concluded with certainty, the study suggests priorities that may inform public health programmes”. They also call for further studies to include younger adults in order to test the impact of intervention measures.
Studies in the past have found that depression and diabetes risk might be modifiable through diet and lifestyle efforts. As I was getting ready to put this post up another study (3) caught my attention, this time it was a Japanese association study which found that “A healthy Japanese dietary pattern characterized by high intakes of vegetables, fruit, mushrooms and soy products was associated with fewer depressive symptoms”. The study is just another illustration of the potential impact that a healthy diet may have on mental health.
(1)K Ritchie et al. Research Designing prevention programmes to reduce incidence of dementia: prospective cohort study of modifiable risk factors. BMJ, 2010;341:c3885 DOI: 10.1136/bmj.c3885
(2)Press release:BMJ-British Medical Journal (2010, August 5). Eliminating diabetes and depression, and boosting education, most likely to ward off dementia. ScienceDaily. Retrieved August 6, 2010, from http://www.sciencedaily.com /releases/2010/08/100805204003.htm
(3) Nanri A et al. 2010. Dietary patterns and depressive symptoms among Japanese men and women. European Journal of Clinical Nutrition. 64: 832–839; doi:10.1038/ejcn.2010.86;
Written by Ani Kowal
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