Mental 'exercise' linked to faster dementia progression

NEW YORK 02 sept 2010– While staying mentally active in old age has been linked to a delayed onset of dementia, seniors who engage in such brain "exercise" may actually have a faster rate of decline once Alzheimer's is diagnosed, researchers reported Wednesday.

The findings, published online in the journal Neurology, do not mean that a mentally stimulating lifestyle is a bad thing.

Instead, the researchers suspect that their findings may point to the "cost" of delaying Alzheimer's onset by keeping the mind active with hobbies, reading, crossword puzzles and the like.

That is, once these mentally active older adults are showing the signs of dementia and are ultimately diagnosed, they may have a more advanced stage of brain damage compared with less mentally active seniors.

This idea fits in with the "cognitive reserve" hypothesis of dementia. That theory basically holds that people who are mentally active can better withstand the gradual brain-cell damage that marks Alzheimer's disease and other forms of dementia. But once that damage reaches a certain threshold, dementia symptoms will become apparent.

So mentally active older adults may develop dementia later than those who "exercise" their brains less often. But once they do develop it, they are in a more extensive state of brain damage.

That, at least, is "the working hypothesis," said Dr. Charles B. Hall, a researcher at Albert Einstein College of Medicine in New York. Hall was not involved in the current study, but is researching the connection between cognitive activities and dementia.

In an interview, he said these latest findings confirm work by his research group and others finding a link between a mentally active lifestyle and a delayed onset of dementia, but also a faster decline once dementia is diagnosed.

The current study, led by Dr. Robert S. Wilson of Rush University in Chicago, included 1,157 older adults who were dementia-free at the outset and were evaluated for cognitive decline over roughly six years.

At the study's start, participants reported on how often they engaged in a number of activities that were considered mentally stimulating -- including reading, doing crosswords or other puzzles, playing games like cards or checkers, watching TV, listening to the radio and going to museums.

During the study period, 614 participants remained cognitively healthy, while 395 developed mild impairment in their thinking abilities, and 148 were diagnosed with Alzheimer's disease.

Wilson's team found that among the group who remained healthy, those who reported a greater number of cognitive activities showed a slower rate of decline in cognitive tests over six years. Test scores remained essentially unchanged among those in the top 10 percent for cognitive activities, but showed a gradual dip among those in the bottom 10 percent.

In contrast, among study participants who were diagnosed with Alzheimer's, those who were the most mentally active at the study's outset showed a quicker rate of decline over time than those who had been the least mentally engaged.

According to Wilson's team, all of this suggests that mentally stimulating activities in older age might "compress" the amount of time a person ultimately spends with dementia symptoms.

However, Hall pointed out that the key limitation of this and past studies on the issue is that they are observational studies. That is, they can show an association between mental activities and dementia onset and progression, but cannot prove cause-and-effect.

"The evidence from observational studies suggests that cognitive activities might delay the onset of dementia," Hall said, "but that has to be confirmed in intervention studies."

In an intervention-type study, participants would, for example, be randomly assigned to regularly perform some sort of mentally stimulating activity and then have their cognitive health followed over time and compared with that of a similar group who did not perform the activity.

If staying mentally active does delay dementia onset, evidence so far suggests the benefit would be modest.

In a study Hall and his colleagues published last year, they found that of older adults who developed dementia during the study period, the most mentally active ones were typically diagnosed just over a year later than the least mentally active men and women.

People in the most active group typically reported 11 "activity days" per week -- meaning, for example, they performed one activity, such as reading, writing or playing games, on all days of the week, and a second activity on four days of the week. The least active group reported four activity days per week.

"This doesn't prevent dementia. This doesn't prevent the (brain) pathology," Hall said. However, he added, if mental activities were found to delay dementia symptoms, or the need for nursing home care, by even a year, that would have a "tremendous public health impact."

"I'm not ready to tell everyone to do crossword puzzles," Hall said. On the other hand, he added, there would be little chance of harm in doing so.

SOURCE: http://link.reuters.com/bar78n Neurology, online September 1, 2010.

Eliminating diabetes and depression, and boosting education, most likely to ward off dementia

Research: Designing prevention programs to reduce incidence of dementia: Prospective cohort study of modifiable risk factors

06 aug 2010--Eliminating diabetes and depression, as well as increasing education and fruit and vegetable consumption, are likely to have the biggest impact on reducing levels of dementia in the coming years, should no effective treatment be found, concludes a study published on bmj.com today.

These findings suggest priorities for future public health interventions.

While the exact cause of dementia is still unknown, several modifiable risk factors have already been identified. These include vascular risk factors (heart disease, stroke, high blood pressure, obesity, diabetes, and high cholesterol), a history of depression, diet, alcohol consumption, and education level.

Based on this knowledge, a team of researchers based in France and the UK estimated which of these risk factors might be most effective in reducing the future burden of dementia, should no effective treatment be found.

Their analysis involved 1,433 healthy people aged over 65 years living in the south of France and recruited between 1999 and 2001. Participants underwent cognitive testing at the start of the study and again at two, four and seven years. A reading test (the Neale score) was also used as an indicator of lifetime intelligence.

Medical history and information on measures such as height, weight, education level, monthly income, mobility, dietary habits, alcohol consumption, and tobacco use was obtained. An individual's genetic risk of dementia was also measured: although it's not a factor that can be changed it served as a useful benchmark for dementia risk.

Results showed that eliminating depression and diabetes and increasing fruit and vegetable consumption were estimated to lead to an overall 21% reduction in new cases of dementia, with depression making the greatest contribution (just over 10%). However, the researchers point out that the direct (causal) relationship between depression and dementia remains unclear.

Increasing education would also lead to an estimated 18% reduction in new cases of dementia across the general population over the next seven years. By contrast, eliminating the principal known genetic risk factor from the general population would lead only to a 7% reduction in the number of new cases over the next seven years.

Given these findings, the authors suggest that public health initiatives should focus on encouraging literacy at all ages irrespective of ability, prompt treatment of depressive symptoms, and early screening for glucose intolerance and insulin resistance (early stages in the development of diabetes).

While these calculations can only provide a crude estimate of impact on incidence, they do make a significant statement about public health priorities in disease prevention in the face of current knowledge, conclude the authors. Further studies including younger adults are clearly needed to test the impact of intervention measures.

A second study, also published on bmj.com today, finds that death rates are more than three times higher in people with dementia than in those without dementia in the first year after diagnosis. The study also says that earlier and better detection of dementia in primary care is needed. An accompanying editorial suggests that key areas to focus on include better education and training in primary care, developing more integrated systems of care, and ensuring that policy makers and commissioners plan services that reflect the effects of dementia on primary care and other services.