Tuesday 12 December 2017

Not all dementia cases are inevitable

Exercise may slow the progression of dementia
Exercise may slow the progression of dementia

Patricia Casey

The adage that, the only certainties in life are taxes and death is hardly a cheerful one. To that, one could add ageing. From the moment of our birth we are getting older and among those over 65, about one in 14 will suffer with dementia according to data from Dementia UK. BBC radio 4 has recently run a very interesting series called How to Have a Better Brain, hosted by Sian Williams and its conclusions and those of some other research provide some cause for optimism.

For over two decades both normal and pathological ageing (also called dementia) have attracted a huge amount of interest, particularly those elements that many be modifiable.

The results suggest that several aspects of our lifestyle may influence the speed at which our brain ages and may also influence the likelihood of dementia developing. These include physical activity, non-physical activity such as brain training, stress, social networks and diet.

Since 1995 the American Centre for Disease Control and Prevention and the American College of Sports Medicine have been encouraging adults to have 30 minutes or more of moderate-intensity physical activity most, but ideally all, days.

The database supporting the benefits of exercise on the brain is building and there is evidence that those who have exercised regularly have less shrinkage of the brain when examined on scans.

For those becoming forgetful, exercise can help boost the oxygen and glucose supply this organ and reduce the risk of vascular disease, one of the causes of dementia.

In addition exercise reduces the risk of diabetes, hypertension and high cholesterol, all risk factors for dementia.

It is too early to claim that it can halt dementia once it has begun but it may slow its progression and may influence certain mental tasks rather than having a more global effect.

In addition to possibly influencing the ageing process, there is much better evidence that exercise influences how we feel - it makes us feel less depressed, at least in the short term.

According to Margaret Gatz of the University of Southern California, based on her work on the Swedish Twin Register, about 70pc of risk for Alzheimer's is likely genetic. But her findings on the role of diabetes and obesity in causing dementia strengthen the argument that a significant portion is within our personal control, and that this proportion will increase if the obesity epidemic we face in Ireland and the US continues.

She found that exercise helped both men and women but, interestingly, that heavy exercise was not beneficial in respect of the ageing brain.

What about brain training? Online word games are hugely popular and are widely advertised as being of benefit. Yet the evidence that the benefits of these translate into everyday life is at best uncertain, although they do make the person more proficient at the particular game.

On the other hand there is evidence that having a lifestyle that has been linked to brain stimulating activities such as playing music, singing, learning languages, writing, reading and so on is associated with a lower risk of dementia, but only, it seems, in women and when dementia does occur its progression is more rapid.

This model of cognitive ageing has led to the "disuse" hypothesis, which suggests that changes in every day experiences and activity patterns result in disuse and consequent "atrophy" of cognitive processes and skills, expressed in the adage "use it or lose it".

So continuing to sing in the local choir or engaging in whatever brain stimulating activity if was one's forte, is highly recommended.

The third factor, stress, is also believed to play a role. One of the areas of the brain involved in the stress response is the hippocampus and it is here that memories are stored. The production of steroids, as part of the stress response, may, in some, cause damage to the cells of this organ resulting in impairment of memory, especially if it is persistent.

It is also recommended that having friends and being socially engaged reduces the risk of cognitive decline although the mechanism by which interpersonal involvement achieves this is unclear.

Finally, what is the role of diet? Are there any foods or supplements that prevent or reduce the memory decline we experience in later years? There is some evidence for omega-3 fatty acids, found in oily fish and for antioxidants found in blueberries. The role of magnesium, found mainly in green vegetables and nuts is uncertain.

Most cases of dementia cannot be prevented but a sizeable number can, and it is within our gift to care for ourselves so that we do not succumb to this heartbreaking condition.

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