Dr Thomas Stuttaford, the Times medical expert, is online every Wednesday. Read his answers to questions on loneliness and dementia

Peter O’Toole, at 74, has rejuvenated his career with his performance as Maurice in the film Venus. Maurice isn’t as vague as his screen friend Ian (Leslie Phillips), but the characters both display classic signs of the forgetfulness of old age. They are constantly searching for their glasses, often when they were around their necks.

Other examples of short-term memory loss exhibited by those of Maurice’s years are so common that they are regarded as the normal benign forgetfulness of old age. These include a failure to remember people’s names, where the car keys were left, or the street where the car was parked.

Although forgetfulness begins to become more marked in the sixties and seventies, and as an isolated symptom usually has little significance, in some cases it can be an early sign of Alzheimer’s disease.

The crucial feature of memory loss in early or moderate Alzheimer’s is that it is obviously progressive and moves on to such difficulties as remembering how to drive the car or work the microwave to forgetting the name of someone close — and then even who they are and whether they have met before.

Alzheimer’s isn’t just about loss of memory. It is about the crumbling of a personality so that the patient initially finds it hard to take simple decisions, such as posting a letter, and can be reduced to a state of agitation by being given any responsibility. Later the frustrations that the person’s disintegrating intellect induces may produce anger and the confused mind may become aggressive and paranoid.

The news this week published in the Archives of General Psychiatry is that research from Rush University Medical Centre, in Chicago, has again demonstrated the importance of the link between Alzheimer’s disease and loneliness. This reinforces earlier studies that indicate that when planning to stay intellectually and physically active in old age maintaining a regular social life may be as vital as exercising the brain by doing the Times crossword and keeping up with current affairs in newspapers, radio and TV. Interests must be kept up.

Living alone is not the same as feeling lonely. About 60 per cent of those who live alone regularly feel loneliness, and 33 per cent find that the loneliness is enough to induce clinical depression. The numbers who feel lonely and depressed are also related to poverty.

Despite the unhappiness and loneliness felt by those who live alone, more than 90 per cent who are miserable about it would prefer to keep their independence and their own company in their own home rather than be moved to a form of communal living.

Alzheimer’s increases a patient’s social insecurity, and a poor memory causes many to be withdrawn. This is why luncheon clubs and the convivial pubs and clubs that Maurice of Venus would haunt become invaluable. In other patients damage to the cerebral cortex may cause disinhibition so that they become garrulous, friendly and sometimes lecherous.

The means of keeping Alzheimer’s at bay include: maintaining a normal blood pressure; taking statins both for its antiinflammatory and cholesterol-lowering ability; having a diet rich in highly coloured fruits and vegetables (lettuce salads don’t count); and taking oily fish regularly, or fish oils such as omega 3, together with a good multivitamin tablet and mineral supplement.

Recent research has reemphasised the importance of folic acid for the elderly as well as for the would-be pregnant. Research is continuing into the effects of supplements such as the phospholipid Phosphatidyl Serine PS, a host of other supplements and diets as well as drug therapy.

Alzheimer’s Research Trust: 01223 843899; www.alzheimers-research.org.uk; Alzheimer’s Society: 020-7306 0606: www.alzheimers.org.uk