Dementia is a broad umbrella term to describe a range of conditions affecting brain function. There are several different types, and Alzheimer's disease is the most common, affecting around 60% of those with dementia in the UK.
Some people have a combination of two or more types of dementia. Alzheimer's is more common in those over 65, with incidence rising with age, so one in six of those over 80 are affected to some degree. It's twice as common in women than men and though in many cases there's no obvious cause, those with a family history may be more at risk. It can occasionally occur in younger people.
The cause is thought to be due to the abnormal accumulation in the brain of amyloid and tau proteins, which gradually destroy brain cells. In addition, there may be a reduction in the level of the chemical acetylcholine in the brain, which acts as a transmitter between nerve cells. It's thought these changes may start up to ten years before a person starts to show the symptoms.
Dementia of all types shortens life expectancy, and on average, those with Alzheimer's live for eight to ten years after their symptoms begin, although those who develop Alzheimer's under 65 often have a faster progression.
Vascular dementia is the second most common type, affecting about 17% of those with dementia. It's rare in people under 65. It's caused by damage to the blood supply to the brain, either as a result of narrowing of the arteries (atherosclerosis), or as a result of a series of very small strokes, which cause pockets of damage to the brain cells.
Compared with Alzheimer's, the progression of vascular dementia can be unpredictable, and a person may seem to stay the same for a long time, before a sudden deterioration. The symptoms are similar to Alzheimer's, but rather than starting with memory loss, the first symptoms are often difficulties planning and organising, making decisions and problems concentrating, with short episodes of confusion.
Vascular dementia is slightly more common in men, and people with heart disease or diabetes are more at risk. Those with vascular dementia live on average for about five years after symptoms begin, but in many cases, their death is caused by a stroke or heart attack.
Less common types of dementia include dementia with Lewy bodies, which gets its name from the tiny deposits that are found in those with the disease. Patients may have recurrent visual hallucinations and problems with movement. Another type, frontotemporal dementia (FTD), refers to damage to the areas of the brain responsible for behavioural and emotional responses, and can make patients appear rude and unfeeling, and to develop ritualised behaviour. It's most commonly diagnosed between the ages of 45 and 65, and life expectancy tends to be between six to 12 years after diagnosis.
How can you diagnose dementia?
Diagnosis can be difficult, as mental function can often be affected by other conditions, such as an infection, an underactive thyroid or lack of some vitamins. GPs use the Mini-Mental State Examination (MMSE), a series of questions to assess a patient's memory, language and attention. Blood tests are also done to rule out other likely causes, and if together these suggest a person may have dementia, they are referred to a specialist hospital memory clinic. Here, further assessments, often including a brain MRI scan, are arranged. The MMSE can also be used to assess changes in a person who has already been diagnosed.
Can you slow the disease down?
While trials try and find a treatment, two main drugs are used to temporarily stabilise or reduce some symptoms of Alzheimer's disease and dementia with Lewy bodies. The first is a group known as cholinesterase inhibitors, such as donepezil. These increase the levels of the chemical transmitter acetylcholine in the brain, which is reduced in Alzheimer's. Between 40 to 70% of people will benefit, with symptoms improving temporarily, over six to 12 months, and then gradually starting to decline again. The second drug is the NMDA receptor antagonist memantine, usually offered to those who can't take cholinesterase drugs because of side effects. This is used in the middle and later stages of the disease. There's also good evidence that exercising both the brain and the body is beneficial for those with all types of dementia.
woman&home is a media partner for Alzheimer's Society. If you're concerned about memory problems or would like to know more about dementia symptoms, visit alzheimers.org.uk or call their National Dementia Helpline on 0300 222 1122.
