Education [1] and mid-life cardiovascular fitness [2] may reduce your risk for Alzheimer's disease. However, a new study in Neurology adds more nuance to previous studies showing the benefits of education and exercise [3]. In this study, investigators not only assessed physical activity at mid-life, but also cognitive activity, rather than education, per se. The investigators also sought to answer whether cognitive and physical activity may reduce the risk of specific types of dementias. Dementia is an umbrella term for diseases associated with cognitive dysfunctions severe enough to affect everyday activities. Alzheimer's disease accounts for 60-80% of dementia, but there are many other forms including vascular dementia (a form caused by brain damage from impaired blood flow) and mixed dementia (a form that displays characteristics of more than one type of dementia).
In 1968-1969, researchers measured the cognitive and physical activity of 800 Swedish middle-aged women (average age of 47). Cognitive activity was broken down into five areas: intellectual, artistic (e.g. going to an art exhibit), manual (e.g. needlework or gardening), participation in a club, and religious activity. The frequency of participation in each activity was rated as none/low (score 0), moderate (score 1), or high (score 2). For instance, if an individual read one book in the last 6 months, she received a score of 1 for the intellectual category. However, if she read many books and/or also wrote, she received a 2 for the intellectual category. Physical activity was scored similarly. For instance, light activity such as walking or cycling for at least 4 hours per week was rated as moderate (score 1). On the other hand, heavier exercise, such as running or swimming several times per week, was rated as high (score 2). Forty-four years later, the investigators asked whether these women were diagnosed with dementia, and if so, which type: Alzheimer's disease, vascular dementia, mixed dementia, or dementia plus a stroke.
Those who had higher scores for cognitive activity in 1968 were 34% less likely to have any form of dementia and 46% less likely to have Alzheimer's disease. Those who had higher scores for physical activity in 1968 were 57% less likely to have mixed dementia and 53% less likely to have dementia plus a stroke. Additionally, the reduced risk for different dementias was dose-dependent, that is, the more cognitive and physical activity in 1968, the greater the reduced risk for certain dementias 44 years later.
An interesting part of the study is that different activities, i.e. physical versus cognitive, were associated with a decreased risk of different types of dementias. In Alzheimer's disease, amyloid-beta plaques accumulate in the brain and may lead to dementia. However, education, and in this case cognitive activity, may help build cognitive reserve which allows someone to maintain normal cognition longer despite the build-up of amyloid-beta plaques [4]. Likewise, physical activity improves cardiovascular fitness which could reduce the risk of cardiovascular complications, such as a stroke.
There are a few limitations of the study. First, all the study participants were women in Sweden. Therefore, the results of this study cannot necessarily be generalized to men or other populations. Second, the investigators only measured physical and cognitive activity at baseline. It is unknown whether the participants maintained their activity over 44 years. Nevertheless, this study adds to previous studies showing that what we do throughout life, even in our 40s, may influence the risk of dementia in our later years.
Nick McKeehan is a member of the ADDF's Aging and Alzheimer's Prevention program. He evaluates the scientific evidence for and against therapies to promote brain health and/or prevent Alzheimer's disease at our website CognitiveVitality.org and contributes regularly to the site's blog. Mr. McKeehan previously served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. Mr. McKeehan received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. He also writes about the biotechnology industry for 1st Pitch Life Science.
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