Indulging in unhealthy modern lifestyle of drinking, smoking and junk food leads to Alzeimer's, new research has revealed.

According to lead researcher Rajan Duara, people who drank two alcoholic drinks a day developed Alzheimer's five years earlier than non-drinkers.

Heavy drinkers and smokers as well as those who indulged in junk food risked succumbing to the disease eight years soon than those with healthier lifestyles.

Puffing more than 20 cigarettes a day resulted in the disease almost two and a half years sooner than patients who smoked less or were non-smokers.

Dr Duara said the results showed that reducing or eliminating heavy smoking and drinking could substantially delay the onset of the disease.

''A delay in the onset of the disease by five years would lead to nearly a 50 per cent reduction in the total number of Alzheimer's cases,'' the Daily Mail quoted him as saying.

Another study by Finnish and US scientists found that people with the highest cholesterol levels in their early 40s were one and a half times more likely to develop the disease than those with the lowest levels. A third study found that exercising between two and five times a week in middle age kept the memory sharp in later years.