Exercise and then a cuppa is the perfect mix to help mental health

In two separate studies, US scientists found that physical activity and regular consumption of tea or coffee both protect against mental decline.

One team led by Dr Zaldy Tan, from Harvard Medical School, Boston, followed the progress of 1,200 elderly men and women with an average age of 76.

Health checks after an average of ten years showed that those who engaged in moderate to heavy levels of exercise had a 40 per cent lower risk of developing dementia than the least physically active.

The trend was more evident in men than in women, the International Conference on Alzheimer's Disease in Hawaii was told.

Professor Clive Ballard, director of research at the Alzheimer's Society, said: "Whether it be a round of golf, a brisk walk or a session on the treadmill, 30 minutes of exercise five times a week can be beneficial at any age.

"The best way to reduce your risk is to combine exercise with a healthy diet, not smoke, and have your blood pressure and cholesterol checked regularly."

The second study, also presented at the conference, suggested that a regular cup of tea or coffee can stave off age-related mental decline.

Scientists led by Professor Lenore Arab, from the University of California at Los Angeles, monitored 4,800 people aged over 65 for more than 14 years.

Participants who drank tea regularly were between 17 per cent and 37 per cent less likely to suffer a reduction in mental ability than non-tea drinkers.

People who preferred coffee were also protected. Drinking coffee more than five times a week lowered the chances of mental decline by 20 per cent.

"In recent years a number of studies have emerged suggesting a good cuppa could be much more than the obvious accompaniment for a biscuit," said Prof Ballard.

"This latest research adds weight to previous research that indicates caffeine could significantly reduce cognitive decline. However, we are still a long way from being able to say for sure that a regular brew will reduce your risk of developing dementia."

Meanwhile, another study presented at the conference has found eating walnuts could stave off dementia.

Mice fed a diet rich in the nuts demonstrated considerably better mental skills when examined nine to 15 months later compared with those not fed any.

The lab animals were genetically engineered to develop Alzheimer's disease as they aged.

Those deprived of the walnuts suffered dramatic loss in abilities - including learning, memory, emotional control and motor coordination - but the mice whose food was made up of either 6 per cent or 9 per cent walnuts were not impaired by these problems.

An estimated 750,000 people in the UK are believed to have dementia. More than half suffer from Alzheimer's, the most common form of the disease. The number of people with dementia is expected to soar to a million by 2025.xz