Why did it happen?
Whenever a change in our lives is forced upon us, we all want to know the reason for it. So it is easy to understand why a diagnosis of dementia in a family member often leads people to try to find some event or factor that might have caused the disease.
If, for example, the symptoms of dementia first became noticeable after moving house, or in the months following retirement, it would be tempting to conclude that the stresses and life changes that accompanied these events were somehow to blame for the onset of the disease.
IT ISN’T YOUR FAULT
Some people go further than this and believe that they themselves may be to blame for what happened. They worry that something they did or failed to do may have caused the disease or made the symptoms worse. It’s all too easy to find yourself thinking ‘If only I’d taken her to see the doctor sooner’, ‘I should have taken more notice of the changes in him’, or ‘I wish I’d been more sympathetic’.
It is very important not to accuse yourself in this way. The symptoms of dementia appear so gradually that it is very hard to notice that something is wrong with someone whom you see every day. Friends and relatives who don’t see the sufferer very often are in a much better position to recognise these gradual changes, and they’re frequently the first to notice a deterioration.
THE CAUSES OF DEMENTIA
The causes of Alzheimer’s disease are as yet unknown, although there are several theories that we discuss later in this chapter. A little more is known about vascular dementia. But, first, let’s look at what does NOT cause the disease. A great deal of research is being carried out to learn more about dementia and why some individuals are susceptible to it. The results of this research show that many of the popular ideas about the causes of the disease are incorrect.
WHAT NOT TO BLAME
Overuse of the brain
There is no evidence that ‘thinking too much’ can cause dementia – you cannot damage or wear out your brain by mental activity.
Stressful life events
Dementia is not caused by sudden changes or adverse events in daily life such as bereavement, divorce, moving house, being admitted to hospital or accidents, although such an event may sometimes bring a hidden dementia to light. The sufferer may have been able to cope previously, but a sudden change or a stressful experience may prove too much so that the symptoms of dementia become noticeable for the very first time. It may appear as if the event has caused the dementia but, in fact, the disease had already taken hold and the event only made it more obvious to other people.
Psychological problems
People who have suffered from anxiety or depression are sometimes thought to be more at risk of developing dementia, but there is no clear evidence that this is so. Depression is sometimes one of the symptoms in the early stages of dementia and this may be why it has mistakenly been regarded as a cause of the disease.
Alcohol
Alcohol, of course, affects brain function at least in a temporary way, so perhaps it is not surprising that many people believe that heavy or prolonged drinking can lead to a loss of brain cells. Sometimes brain damage does occur in malnourished alcoholics but this type of dementia is rare and is different from Alzheimer’s disease or vascular dementia.
Smoking
It has been suggested that smoking may actually protect people against Alzheimer’s disease, but as yet there is not a great deal of evidence to support this. However, smokers do seem to be more likely to develop another form of dementia known as vascular dementia.
Head injury
Everyday knocks, such as banging one’s head on a kitchen cupboard, do not cause dementia, but people such as professional boxers who have been subjected to repeated severe blows to the head do sometimes develop a form of dementia. Experts argue about whether a single violent injury to the head, serious enough to result in loss of consciousness, increases the risk of Alzheimer’s disease. If it does, the risk is not increased very much. Most people who survive a head injury will not get Alzheimer’s disease.
Old age
Dementia is not caused by old age, and the majority of elderly people will not develop it. However, like almost every other illness, dementia is more likely to occur in older than in younger people.
MODERN THEORIES
There is a major research effort into the origin of Alzheimer’s disease and explanations include genetic and environmental causes.
Genetics
In a small proportion of cases, all of whom develop the disease at an unusually early age, Alzheimer’s disease runs strongly in their families. In some of these families, defective genes located on chromosome 1, 14 or 21 have been identified as the cause of the disease. This explanation, however, is the exception rather than the rule. Only a very small percentage of the total number of cases of Alzheimer’s disease can be put down to these defective genes.
A genetic predisposition for the more common form of Alzheimer’s disease, which affects older people, was discovered a few years ago. People who carry a particular form of the gene for apolipoprotein E are at increased risk. This gene contains the information that the body needs to make a protein that is important for the development and maintenance of the brain. There are three variants of this protein.
There is now good evidence that possessing one of these variants leads to an increase in the risk of developing Alzheimer’s disease later in life. How this variant of apolipoprotein E acts to increase susceptibility to Alzheimer’s disease is not yet understood.
Environmental causes
A very large number of possible environmental factors that might cause Alzheimer’s disease have been investigated. These have included foreign travel, type of occupation, using chemicals, taking drugs and medicines, tea and coffee drinking, and malnutrition. There have also been studies to find out whether people who have had a surgical operation or a general anaesthetic or who have suffered from some other disease are more likely to develop Alzheimer’s disease. The finger of suspicion does not point very strongly at any of these possibilities at present.
There is some evidence that the way the brain develops in childhood and adolescence may be important in determining whether a person develops Alzheimer’s disease in later life. People whose brains are larger or who are more highly educated seem to be less likely to show symptoms of the disease. We don’t yet know why this is, but one theory is that their brains have ‘reserve capacity’ so that, even if there are physical signs of the disease within their brains, their mental abilities are affected little.
Many people believe that mental faculties deteriorate if they’re not used enough – this is sometimes known as the ‘use it or lose it’ theory. According to this view, people are less likely to become demented if they remain mentally active and have lots of interests. Recent research suggests that there may be some truth in this. Scientists have found that old people who spend more time engaged in mentally stimulating activities, such as reading, doing crosswords, playing board games or cards, going to films or exhibitions or playing a musical instrument, do seem to have a lower risk of developing Alzheimer’s disease.
VASCULAR DEMENTIA
This form of dementia has its origin not in the nerve cells of the brain but in disease of the small blood vessels that carry oxygen and fuel to this organ. One very important factor that leads to disease of blood vessels is raised blood pressure. People whose blood pressure has been high for a number of years are more likely to develop vascular dementia.
Another factor that makes this type of dementia more likely is smoking cigarettes. This is because it increases the tendency of the blood to clot. The combination of disease of small blood vessels and blood that tends to clot too readily is dangerous. It is likely to lead to blockage of blood vessels and to damage to the areas of the brain supplied by the blocked vessels.
