By Megan Rauscher

 NEW YORK (Reuters Health) – Results of a new study support a number of previous prospective studies that have shown that staying mentally active reduces the risk of developing Alzheimer’s disease (AD) or its precursor, mild cognitive impairment.

 As part of the longitudinal Rush Memory and Aging Project, more than 700 people in Chicago, Illinois with an average age of 80 underwent yearly cognitive testing for up to 5 years and provided information on current and past cognitive activity.

 "The cognitive/mental activities we asked about included visiting a library or museum; reading newspapers, books or magazines; attending a concert, play or musical; and writing a letter," Dr. Robert S. Wilson told Reuters Health.

 Ninety of the study subjects developed AD. In the July 27th issue of Neurology, Dr. Wilson of Rush University Medical Center, Chicago, and colleagues report that "more frequent participation in cognitive activity was associated with reduced incidence of AD (hazard ratio, 0.58)."

 A cognitively inactive person in old age was 2.6 times more likely to develop AD than a cognitively active person, the team found.

 "The association remained after controlling for past cognitive activity, lifespan socioeconomic status, current social and physical activity, and low baseline cognitive function," the investigators report.

 Frequent cognitive activity also protected against mild cognitive impairment and cognitive decline. "Our results suggest that regardless of how mentally active people have been prior to old age, higher level of mental activity in old age reduces the risk of developing an AD-like dementia and mild cognitive impairment," Dr. Wilson said.

 Postmortem brain autopsy performed in 102 subjects who died during the study failed to show a correlation between level of cognitive activity and neuropathology findings.

 It is likely, Dr. Wilson said, that cognitive inactivity is "truly a risk factor for AD and not simply an early consequence of the disease — because cognitive activity was not related to AD pathology and people with early AD symptoms did not show accelerated decline in mental activity."

 The findings of this study underscore the importance of being mentally active in old age, the clinicians conclude.

 Neurology 2007;69.