Author response: Healthy lifestyle and the risk of Alzheimer dementia: Findings from 2 longitudinal studies
KlodianDhana, Assistant Professor, Rush Institute for Healthy Aging, Rush University Medical Center
Denis A.Evans, Professor, Rush Institute for Healthy Aging, Rush University Medical Center
Kumar B.Rajan, Professor, Department of Public Health Sciences, University of California at Davis
David A.Bennett, Professor, Rush Alzheimer’s Disease Center, Rush University Medical Center
Submitted July 27, 2020
We greatly appreciate the comment to our recent article1 by Drs. Uleman and Olde Rikkert, which emphasizes the potential importance of lifestyle factors in Alzheimer’s dementia prevention.
We agree that the relative risk estimates—e.g., hazard ratios—in observational studies are unlikely to be comparable to estimates from clinical trials. Observational studies likely capture long term habits beyond the duration of randomized controlled trials (RCTs). Further, there is also the issue of residual confounding. We agree that the results of any observational study—even of high quality—cannot demonstrate causality. As the authors note, RCTs are expensive and time consuming. Perhaps the most important role of observational studies in the prevention of Alzheimer’s dementia is to suggest which of the many potential interventions appropriate to a wide population base most deserve rigorous examination in RCTs. We agree that causal loop diagrams deserve exploration as a means of doing so. We think strongly encouraging and funding both observational studies and RCTs of adequate size and design, however, is of greater importance in finding the best path to prevention of this common condition of dreadful impact on public health.
Disclosure
The authors report no relevant disclosures. Contact journal@neurology.org for full disclosures.
Reference
Dhana K, Evans DA, Rajan KB, Bennett DA, Morris MC. Healthy lifestyle and the risk of Alzheimer dementia: Findings from 2 longitudinal studies. Neurology 2020 Jun 17.
We greatly appreciate the comment to our recent article1 by Drs. Uleman and Olde Rikkert, which emphasizes the potential importance of lifestyle factors in Alzheimer’s dementia prevention.
We agree that the relative risk estimates—e.g., hazard ratios—in observational studies are unlikely to be comparable to estimates from clinical trials. Observational studies likely capture long term habits beyond the duration of randomized controlled trials (RCTs). Further, there is also the issue of residual confounding. We agree that the results of any observational study—even of high quality—cannot demonstrate causality. As the authors note, RCTs are expensive and time consuming. Perhaps the most important role of observational studies in the prevention of Alzheimer’s dementia is to suggest which of the many potential interventions appropriate to a wide population base most deserve rigorous examination in RCTs. We agree that causal loop diagrams deserve exploration as a means of doing so. We think strongly encouraging and funding both observational studies and RCTs of adequate size and design, however, is of greater importance in finding the best path to prevention of this common condition of dreadful impact on public health.
Disclosure
The authors report no relevant disclosures. Contact journal@neurology.org for full disclosures.
Reference