Persons most commonly affected: Both sexes affecting people in old age (rarely under 65 years of age). Blacks, smokers, people with a history of high blood pressue, those who have had a head injury, especially a serious one, are at greatest risk.

Organ or part of body involved: Brain

Symptoms and indications: The early indications are increased forgetfulness and increased difficulty in performing simple, normal tasks to which the person is well accustomed. There may be changes in personality out of character with the person's normal behaviour. There is a progressive deterioration in the person's mental and physical abilities and memory. In the very late stages of the disease, the person is incapable of any tasks, may be doubly incontinent, may have lost the power of speech, suffer from some paralysis and have total loss of memory, loss of sense of time, and there may be signs of emotional instability, with mood swings, aggressiveness and antisocial behaviour.

Causes and risk factors: The cause is not known but is a subject of ongoing, intensive research. Some researchers believe that there is a connection with the deposition of aluminium in brain cells. Some believe that is it due to so-called slow viruses (viruses acquired early in life that take many years to do their damage). Heredity also seems to play a part. It is generally agreed that hardening of the arteries is not a cause. The disease does not appear to be contagious, nor it is caused by emotional stress.

Prevention: It is advisable to avoid cooking acidic fruits in aluminium pans to avoid contamination with aluminium. Researchers from the Karolinska Institute in Sweden have found that people who exercise at least twice a week are 60% less likely to get Alzheimer's disease and other types of dementia. The most common type of exercise is walking and cycling.

Eat a low-calorie and balanced diet making sure you include plenty of oily fish and cold-pressed vegetable oils, such as extra virgin olive oil, fresh vegetables and fruit. Walnuts, almonds, and other nuts as well as cold water fish. like salmon, tuna, and mackerel, give you lots of omega-3 fatty acids. This form of unsaturated fat helps improve your brain's performance and your memory. Zinc may be deficient in those with Alzheimer's. Boost your intake by eating pumpkin seeds, black-eyed peas, wheat germ, tofu and seafood.