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  • Can Cognitive and Physical Activity in Midlife Reduce the Risk of Dementia in Later Years? Researchers Say Yes

    Staying intellectually engaged and physically active is an important part of a healthy lifestyle at any age, but now authors of a new study from Sweden say that cognitive and physical activity in midlife can pay off years later by reducing the risk of some forms of dementia. The results of the study showed that individuals who were cognitively active in midlife reduced their risk for Alzheimer's disease (AD) by as much as 46%, while those who were physically active reduced the risk of later dementia and stroke by 53%.

    The study, e-published ahead of print in Neurology, followed 800 women from 1968 to 2012, noting levels of cognitive and physical activity at baseline, and analyzing rates of various types of dementia as the women aged. Baseline activity ratings were taken when the women were 38-54 years old (average age, 47) as part of the Prospective Population Study of Women.

    Cognitive activity was assessed on 0-2 point scale based on each woman's level of involvement in 5 areas of activity: intellectual, artistic, manual, club, and religious. Activity in each category could range from no/low (0) to high (2). Information was obtained via "semi-structured psychiatric interviews."

    Physical activity (PA) was assessed using the Saltin-Grimb Physical Activity Level Scale, which assigns PA levels on a 4-point scale: 1 - completely inactive; 2 - light PA for at least 4 hours a week; 3 - regular physical training such as running or swimming for at least 2-3 hours a week; and 4 - regular intense physical training such as running or swimming several times a week or participating in competitive sports.

    After the initial assessments in 1968-69, participants were reexamined for cognitive and neurophysiologic function in 1974-75, 1980-81, 1992-93, 2000-03, 2005-06, and 2009-10. The last 4 follow-ups included "close informant interviews" that provided additional, third-party information on behavioral changes, activities of daily living, and, if it had occurred, the participant's age at onset of dementia. Information on potential confounders—education, socioeconomic status, hypertension, smoking, diabetes, angina, psychological stress, and depression—was also gathered.

    Between 1998 and 2012, 194 women—nearly 25%--developed dementia over an average 31.5-year timespan. Average age of dementia onset in the group was 79.8 years, and the overall average age at death was 80 years. In addition to total dementia rates, researchers looked at rates of AD, vascular dementia (VaD), "mixed dementia" (both AD and cerebrovascular disease [CVD]), and "dementia with CVD,” which encompassed individuals with any type of dementia and stroke.

    When researchers began analyzing rates of dementia in terms of baseline levels of cognitive and physical activity, they discovered a connection between that activity and lower risk of dementia, albeit in different areas: cognitive activity was associated with a 46% risk reduction for Alzheimer's disease, while PA was associated with a 37% risk reduction for mixed dementia and a 53% drop in risk for dementia with CVD. Both types of activity reduced overall dementia risk by about 33%. The reduced risk rates remained even when researchers factored in the potential confounders. Neither type of activity seemed to reduce the risk for VaD alone.

    Authors write that a possible explanation for the reduced risk has to do with the ways in which cognitive and physical activity increase "cognitive reserve," or "how flexible and efficiently one can make use of available brain reserve," even when measurable factors such as brain size and neuronal count are lower. It's a concept echoed in a study that appeared in Neurology earlier this year, in which researchers reported that higher levels of PA and motor skills not only lowered the odds of dementia, but seemed to buffer its severity if it did occur.

    Authors of the Swedish study acknowledge some significant limitations in their study, including its focus on a fairly demographically homogenous group, and the lack of any data on whether the women active in midlife remained so as they aged. Also "impossible to rule out," according to the researchers: the possibility that the lower cognitive and physical activity levels reported by some of the women were "manifestations of very early pathologic processes in dementia disorders."

    Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA. For synthesized research and evidence-based practice information, visit the association's PTNow website.

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