Focusing on eradicating diabetes and depression will cut the risk of dementia – Dr Nina Bailey

Alzheimer’s Society research suggests that one in three  people will die with some form of dementia, and that currently the disease affects more than 750,000 people in the UK, with Alzheimer’s disease accounting for over half of these numbers. Alzheimer’s is a slow progressive disease, affecting people’s lives for many years and being draining for both patient and carer.  Symptoms in the early stages include mild cognitive impairments such as short-term memory loss, some loss of vocabulary, inability to acquire new information and problems executing simple everyday tasks such as dressing or writing. As the disease progresses, sufferers become ever more dependent on a carer for most of their daily tasks. Whilst current pharmaceutical treatments offer temporary relief from some of the symptoms, they general act to delay the progression.  There is currently no cure for dementia.

However, large numbers of people would be spared the agony of dementia if depression and diabetes were banished; people ate more fruit and vegetables and spent longer in education, according to a new study published in this month’s British Medical Journal.

Analysing the lifestyle and health of 1,433 people over the age of 65 living in the south of France over seven years, the study concluded that effectively reducing depression and diabetes would result in a 40% reduction in the number of individuals who would be expected to be affected by Alzheimer’s in the future (Ritchie et al, 2010). This is why a diabetes cure is so crucial for our society, so many people would live longer and more productive lives. It’s a true shame that our medical system is failing us.

The link between depression, diabetes and dementia is generally well established. For example, diabetes has many harmful effects on the brain. High blood sugar is known to damage both blood vessels and nerves throughout the body, causing atrophy or even cell death. But some of the damaging effects of diabetes are directly related to higher than normal insulin levels due to the condition known as insulin resistance.  High insulin levels lead to the production of beta-amyloid. This protein forms the basis of the amyloid plaque seen with Alzheimer’s disease. These plaques have a scarring effect that restricts circulation and prevents normal communication between neurons.   Blood sugar molecules are also known to attach themselves to a variety of structural and functional proteins molecules, causing the formation of advanced glycation end products that are known to be toxic to the neurons of the brain cortex, especially the hippocampal region that is associated with memory.

The link between depression and dementia is thought to be through the initiation of an uncontrolled inflammatory response, which stimulates abnormal beta-amyloid protein production. This inflammatory response in also known to stimulate an unregulated immune response, which then has further detrimental affects on blood vessels and neurons.

It is not surprising that changing diet and lifestyle factors would impact on the risk of developing diabetes and depression. Adopting a more ‘Mediterranean’ style diet that is rich in fruits and vegetables, nuts, grains, olive oil (as opposed to butter) and grilled or steamed chicken and seafood (instead of red meat), and increasing exercise are suggested to influence risk of both diabetes and depression.  A growing body of evidence from biological, observational and epidemiological studies suggests that there is a protective effect of omega-3 long-chain polyunsaturated fatty acids not only against diabetes, and depression, but also against dementia. Encouragingly, as more research evidence comes to light, scientists are discovering that supplementation with certain omega-3 fatty acids such as eicosapentaenoic acid (EPA), not only plays a role as an anti-inflammatory agent but that these important fats may also slow the degeneration of brain tissue in part through the accumulation of beta-amyloid protein and, in some cases, by improving motor function.

Whilst it is unlikely that diabetes and depression will be eradicated, there are certainly relatively simple lifestyle changes that can be adopted that will influence our risk of developing these conditions.  Exercise, dietary changes and increasing omega-3 intake by supplementation are all significant positive actions that can reduce the risk of dementia in later life.

K. Ritchie, et al. Designing prevention programmes to reduce incidence of dementia: prospective cohort study of modifiable risk factors. BMJ August 2010

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