by Brett Foley

American researchers have found compelling new evidence that people who spend long hours in front of television are at increased risk of Alzheimer's disease.

Research published today suggests that adults with hobbies that exercise the brain -- such as reading, jigsaw puzzles, chess or knitting -- are two-and-a-half times less likely than others to have the disease.

The study of people in their 70s found that those who regularly participated in intellectually challenging hobbies during their younger adult years tended to be more protected against Alzheimer's.

Australian researchers said yesterday the research added to evidence suggesting a healthy, stimulated mind -- through education and by intellectually demanding professions -- will help delay the onset of the degenerative brain condition.

In the study, appearing in the Proceedings of the National Academy of Sciences, Dr. Robert P. Friedland and his colleagues from Cleveland questioned about 550 people in their 70s about their leisure activities during early (age 20 to 39) and middle (age 40 to 60) adulthood. Of the participants, 193 were Alzheimer's patients and 358 were not. The information about the Alzheimer's patients was gathered from family and friends, while the control group was interviewed directly.

Activities were divided up into passive, such as watching television, or listening to music; intellectual, such as reading, crossword puzzles, musical instruments, board games, knitting or woodwork; and physical, such as bike riding, swimming or walking.

They found intellectual activities seemed particularly protective, with those whose leisure centered on mind-challenging hobbies were about two-and-a-half times less likely to develop Alzheimer's. Intellectual stimulation in early and middle adulthood did not provide absolute protection against Alzheimer's in late adulthood, said Dr. Friedland, but the activities could delay the disease for years.

The acting medical director of Kingston Aged Care Centre, Barbara Workman, said the research was important because it established that how people used leisure time was important in delaying Alzheimer's.

She said the simple analogy was, if you exercise your muscles it will take you longer to become weak, therefore if you stimulate your brain to work harder, it will take longer to become weak.

"I think that these things are a very simple preventative measure," she said. "People take great care in what they eat and exercise to prevent cardiovascular disease and these types of activities appear to provide protection for the brain."

Dr. Richard Whiting, a geriatrician at Sunshine Hospital, said the development of a stronger neuronal network make the brain more resistant to early onset of Alzheimer's. He said the research sent an important message to young adults that their actions now had great bearing on future physical and mental health.

"A number of diseases that affect us in old age can be prevented or have their impact lessened by your education, work and exercise practices during adulthood," he said.