"The idea that mental activity is good for the brain is not unlike the idea of 'use it or lose it' when it comes to keeping the body fit," said Andel. Using data from the Swedish Twins Registry, a population-based dataset of twins living in Sweden, the team analyzed information on like-sexed twins born between 1886 and 1925. The study was funded by the Alzheimer's Association and the National Institute on Aging.
In the 1960s, these twins had filled out questionnaires about their leisure activities, which included reading, social visits, theater and movie going, club and organization participation, gardening and other outdoor activities, and playing sports. They subsequently participated in clinical follow-ups in the 1980s and 1990s, when they where tested for Alzheimer's disease and other dementias.
In an analysis of 107 of the pairs where one twin was diagnosed with some type of dementia while the co-twin was cognitively intact, the twin who did not develop dementia reported greater overall participation in leisure activities. Moreover, among female twin pairs, the twin who participated frequently in "intellectual-cultural activities" showed a reduced risk of Alzheimer's disease.
This study cannot entirely rule out the possibility the twins had factors in their youth that led both to greater levels of activity and to reduced risk of dementia. However, because it is a twin study, genetics and early experience are controlled for. In addition, the analyses controlled statistically for differences in amount of education. "The difference made by greater overall leisure activity is not explained by differences in either education or similarities found within twin pairs such as early-life environment and, possibly, even genes" said Andel. "However, not all leisure activities may be equally protective."
Crowe pointed out that few studies have looked at the relationship between leisure activity and its impact in later life using prospective activity data and twin design. Andel also explained that the strength of the research was based upon the 20-year time lag between data collection and evaluation. The research team is currently working on a study that will test whether intellectually stimulating occupations may also be protective.
The Journal of Gerontology: Biological Sciences is a refereed publication of The Gerontological Society of America, the national organization of professionals in the field of aging.
The article abstract is available online at http://psychsoc.gerontologyjournals.org/cgi/content/abstract/58/5/P249.