that the figures can be broken down as follows:
The obvious question is whether dementia will become more common as we live longer. Thanks to advances in science, medicine and technology, as a species we’re living increasingly longer. Life expectancy until 30,000 years ago is believed to have been less than 30 years, and right up until the 1800s it was common for adults to die by the age of 40. Now the average man in the UK can expect to live for 78.9 years, while a woman can make it to the ripe old age of 82.7.
Over the next few decades these figures are expected to rise along with the proportion of older people in the population as a whole. According to government figures, currently 10 million people in the UK are over 65 years of age. By 2035, it’s estimated that another 5.5 million more elderly people will be resident in the UK, rising to around 19 million by 2050.
A boy born in the UK in 2030 will have a good chance of living until he’s 91, and a girl to 95. Given the rising chance of developing dementia with age, it’s feared that cases will become far more common as a result of this boom in life expectancy.
One of the commonest misconceptions about dementia is that it equals Alzheimer’s disease. Alzheimer’s disease certainly does equal dementia, but numerous other causes of dementia also exist.
Also consider mild cognitive impairment, which is not yet dementia but not part of the normal ageing process either. For 40 per cent of those who show signs of cognitive impairment, dementia is unfortunately their next step, but for the remainder, their symptoms will either not develop further, or may even be reversible if they are due to depression or the effects of an acute infection.
Considering the ‘big four’ types of dementia
On safari in Africa, the guides bust a gut to make sure that you get the best chance of glimpsing the so-called ‘big five’: lions, African elephants, Cape buffalo, leopards and rhinoceros. Dementia can be broken down into the ‘big four’: Alzheimer’s disease, vascular dementia, Lewy body disease and fronto-temporal dementia. Below is a quick field guide to each. (Chapter 3 describes each type of dementia in detail.)
Alzheimer’s disease
Alzheimer’s disease is the really big one and the most common cause of dementia worldwide. In the UK it’s the cause of dementia in 62 per cent of cases, accounting for the symptoms of around 420,000 people.
Alzheimer’s is a physical disease that leads to the production of abnormal protein deposits in brain cells, called plaques and tangles. These deposits stop the cells working effectively and eventually kill them off. As the disease progresses, this damage spreads to different parts of the brain, adding to the severity of the symptoms. Symptoms involve changes in memory and other thought processes, alteration of mood and loss of ability to carry out tasks needed for day-to-day living.
Vascular dementia
After Alzheimer’s disease, vascular dementia is the next most common cause of dementia, affecting about 112,000 people – roughly 17 per cent of the total cases of dementia in the UK. It occurs because of damage to blood vessels around the brain, which in turn limits blood flow and thus oxygen supply to brain cells.
Symptoms are similar to those seen in Alzheimer’s disease, but depend on which parts of the brain the reduced blood flow affects. A person who has experienced strokes may also suffer with additional weakness or even paralysis of limbs and speech difficulties.
Because circulation problems become more common as we get older, 10 per cent of people have what’s described as mixed dementia, where they have Alzheimer’s disease alongside vascular dementia, and a mix of symptoms of both.
Lewy body disease
A much rarer sighting, people with Lewy body disease make up only 4 per cent of the number of dementia cases – an estimated 25,000 people. Lewy bodies are protein deposits that damage brain cells. They’re also found in the brains of people with Parkinson’s disease, and as a result an overlap exists in the symptoms of people with these two conditions.
The symptoms of Lewy body dementia are similar to those of Alzheimer’s, but sufferers also develop muscle stiffness, tremors and shakiness in their limbs, and slower movement. They can also experience visual hallucinations, commonly seeing animals or people around them that aren’t really there.
Fronto-temporal dementia
Fronto-temporal dementia is the smallest of the ‘big four’, affecting 11,000 people in the UK and representing around 2 per cent of total dementia cases. It’s also the most likely of the four types of dementia to be diagnosed in people under the age of 65.
This type of dementia is named because of the areas of the brain that it affects most: the frontal and temporal lobes. These areas of the brain are involved in memory and personality. Thus fronto-temporal dementia shares many of the features of Alzheimer’s disease, but has other symptoms, including strange or sexually disinhibited behaviour, lack of empathy, poor personal hygiene, apathy and loss of motivation, increased appetite for sweet or fatty foods, and repetitive and compulsive speech and actions.
Mild cognitive impairment: Dementia lite?
Dementia clearly isn’t simply a memory problem, because it affects other thought processes along with mood and the ability to carry out all sorts of everyday tasks. Mild cognitive impairment is often seen as a diagnosis that lies somewhere between full-on dementia and the limitations that occur as a result of a normally ageing brain.
Like dementia, mild cognitive impairment can affect a variety of normal thought processes, but it doesn’t impact mood or a person’s ability to perform day-to-day functions. And, while it can be a sign of impending dementia for many, especially those with Alzheimer’s disease, around 60 per cent of people who develop mild cognitive impairment don’t get any worse.
The normally ageing brain
It’s no secret that as we get older bits of us start to wear out and don’t work quite as well as they once did. Joints become creakier, backs ache, eyesight isn’t quite as clear, hair falls out or goes grey, once excitable parts of the body barely raise a smile and memory isn’t as sharp as it used to be.
