30 Aug Study Supportive of Modest Effect of Cognitive Activity on Prevention of Dementia
MedicalResearch.com Interview with:
Dr. Deborah Blacker
Deborah Blacker MD, ScD
Director of the Gerontology Research Unit
Department of Psychiatry
Massachusetts General Hospital
MedicalResearch.com: What is the background for this study? What are the main findings
Response: Many observational studies have found that those who are cognitively active have a lower risk of developing Alzheimer’s disease or any type of
dementia.
However, we and others have been concerned that these findings
might be spurious due to two potential biases:
- 1) confounding, meaning that those who are cognitively active have lower rates of Alzheimers disease for another reason, in particular the effect of greater education,
which is associated with both lower risk of Alzheimers and higher levels
of cognitive activity; and - 2) reverse causation, meaning that theassociation could be due to a reduction in cognitive activity among those already in the long preclinical phase of cognitive decline before Alzheimers dementia (rather than the lack of cognitive activity causing
the Alzheimers).Our study performed a systematic review of the literature on the association, and then a set of bias analyses to assess whether confounding or reverse causation could account for the observed associations.
MedicalResearch.com: What are the main findings?
Response: Our systematic review identified 12 papers meeting prespecified inclusion
criteria, and describing results from nearly 14,000 participants followed
for an average in the range of 2 to 6 years. The studies measured
cognitively activity differently, but all showed reduced rates of
developing Alzheimers disease among those who were more cognitively
active. Our bias analysis showed that the degree of protection suggested
in the studies was unlikely to be accounted for by confounding, as the
impact of education and related factors was not large enough to undermine
the observed association. The finding for reverse causation was less
clear, and a spurious effect due to a slowdown in cognitive activity in
the early preclinical stages of Alzheimers could not be ruled out.
MedicalResearch.com: What should readers take away from your report?
Response: The evidence for cognitive activity to protect against dementia is
somewhat stronger on the basis of these findings. However, people should
be aware that these effects are modest, and that there is no evidence for
one kind of activity over another. I tend to advise people to choose
cognitive activities that they enjoy for their own sake, and not to spend
money on programs claiming to protect against dementia.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We’ d like to see longer term studies that use systematic approaches to
measure the degree of cognitive activity so that results can be compared
and combined across studies, and careful control for education and other
confounding factors.
We’d also like to see studies that try to disentangle the impact of lifelong cognitive activity vs. late-life cognitive activity. And of course we’d like to see clinical trials,
particularly those that look at whether cognitive activities and training
programs can have benefits beyond getting better at the specific task
involved. But some questions, like the impact of decades of cognitive
activity, are better studied in observational settings.
MedicalResearch.com: Is there anything else you would like to add?
Response: This study highlights the role of careful analytic techniques to make the
best possible use of data arising from observational studies rather than
clinical trials.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Citation:
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Last Updated on August 30, 2016 by Marie Benz MD FAAD