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Many articles will claim that there is “proof” or researchers have “proven” that two things are connected. However, researchers use the word “proof” very cautiously. Here’s a study that examines the relationship between exercise and dementia. It might help you to think more carefully about how you use this term.
The study was published in Neurology under the title Midlife cardiovascular fitness, dementia: A 44-year longitudinal study in women (the CNN summary is also available). The following research was done and some convincing results were obtained:
191 Swedish women aged 38 to 66 years were tested for their cardiovascular fitness.
During the tests, which involved stationary biking exercise, their blood pressure was measured and they were connected with an electrocardiograph.
Based on their results, “…the ladies were divided into three groups: 59 were classified as “low fitness”, 92 as “medium fitness”, and 40 as “high fitness”.
The tests were administered in 1968, and the women were followed for 44 year to determine if they had been diagnosed with dementia.
Results: Overall, 23% developed dementia among the women in the study. However, dementia was only found in 45% of the women in the “low-fit” group.
Do you see the evidence that exercise can prevent dementia?
This study, however impressive, cannot lead to a confident conclusion regarding the role of exercise in preventing dementia. These results are correlational, but we all know that correlation does not prove causation.
Problem is, people who exercise may also eat a healthier diet. Is it exercise or diet that causes dementia to decrease? Are people who exercise more likely to also be more social ? ?
While the study can be said “to provide some evidence” for a causal link between exercise, dementia, it cannot be called “proof”. We don’t know what high-fit women did in their lives to cause their lower levels of dementia.
One factor that can give us confidence that exercise can lower your chances of developing dementia, is the fact that there are many studies that have been conducted in very different ways that also support this conclusion.
Discussion Questions and Activities
You can share this idea with students by having them work in small groups of 2-3 people to generate alternative hypotheses. These are some questions to ask:
Why is the issue of exercise and dementia so difficult to study?
How would you set up a new study to examine the relationship between exercise and dementia?
Students may want to present their ideas in class. Students can also give their opinions on whether the ideas presented by each group would lead them to strong conclusions about the connection between dementia and exercise. Ask questions if students aren’t clear about the group’s ideas:
Can you give us an example of what you are talking about?
Could you be more specific?
While no single study can prove a connection, they can be combined to give us confidence in a relationship.