Carers of people with dementia

Ideas about causes of dementia

Those more likely to develop dementia include: elderly people, people with Down's syndrome, people who have had severe head or whiplash injuries, people who smoke, and those who have high blood pressure, high cholesterol levels or diabetes and those with a family history of dementia. Among the very elderly (old age is the most important of these 'risk factors') 1 in 6 people over the age of 80 will develop dementia (Alzheimer's Society 2015). Although it is not possible to do anything about most of the causes, some research suggests that certain changes to lifestyle (maintaining a good diet, exercising regularly, and avoiding excessive consumption of alcohol) may help to protect against dementia.

Among the people we talked to, family history was widely acknowledged as a cause of Alzheimer's, although many of the carers were not aware of dementia in the family. Some knew that early onset forms were more likely to have a genetic cause. In families where living to a ripe, and mentally agile, old age was considered normal, people found it hard to understand why it should have happened. Parents often hoped that family history was not so important, anxious that their children would not be affected.

Everyone we interviewed was asked if they had any theories about causes. Only a few said they had never really thought about it, or thought that it was just caused by old age. Some had spent a lot of time reading about dementia and puzzling over what might have caused it in their parent or partner. People compared the lifestyle and exposures of people within their family who were thought to be similar, yet had not developed dementia, to try to identify the cause. One wife thought that it might have been caused by a viral infection or whiplash after an accident, reasoning that in every other way her husband had had a lifestyle identical to her own.

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Several people mentioned another serious illness as a possible trigger - one daughter knew of three women who had been treated for breast cancer shortly before they developed Alzheimer's and wondered if there could be any connection.

Stress (particularly as a result of bereavement), exposure to chemicals, general anaesthetic, heavy drinking, using aluminium cooking pots and having a blow to the head were all mentioned as possible causes. In some cases it was thought that the combination of an underlying susceptibility and a trigger was likely. Sometimes it was hard to say whether behaviour such as heavy drinking, depression or work related stress was a trigger or an early sign of the disease.

A nurse whose husband had Pick's disease was disappointed that no-one seemed interested in exploring possible causal factors, such as his exposure to environmental pollutants. She describes how an early encounter at the clinic encouraged their view that agricultural pesticides might be to blame.

There was some confusion about smoking. Some had heard that smoking might protect people from dementia, while others were aware that vascular dementia could be caused by smoking. One family were surprised when the doctor suggested smoking was the cause of their father's dementia since he only smoked a very occasional cigar and had not been known to smoke a cigarette in nearly 40 years.

Although searching for a “cause” can be helpful for some families, in most cases no single cause will ever be identified. It is likely that complex genetic factors play a part in susceptibility to dementia, and then lifestyle and environmental factors further modify the risk. The observed link between illness and onset of dementia may in some cases be explained by a “delirium” (or acute confusional state) secondary to the illness exposing some underlying cognitive impairment, or the early stages of dementia. Similarly, the link of onset of dementia with major life events may be explained by already present symptoms of dementia being exposed under stress. 
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Last reviewed March 2015.

Last updated March 2015.

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