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To the Editor: In their randomized controlled trial, Dr Lautenschlager and colleagues¹ investigated the effect of physical activity on the cognitive function of older adults at risk for Alzheimer disease. We have some concerns about the study design.

First, the placebo effect was not investigated in this trial. Participants were not blinded to group assignment and those in the physical activity group may have had more confidence in performing the cognition test because they were aware that they were in the intervention group. Previous studies have found that confidence can enhance the performance on cognition tests.²

Second, some factors that may influence the cognitive function of older persons were not studied. For example, social support has a protective association with cognitive function among elderly persons.³ In one study, bright light was found to have a modest benefit in improving some cognitive symptoms of dementia.⁴ In the study by Lautenschlager et . . . [Full Text of this Article]

Shengjun Wu, PhD
Department of Psychology
Faculty of Aerospace Medicine

Jie Liang, MD
State Key Laboratory of Cancer Biology Institute of Digestive Diseases

Danmin Miao, MD
psyfmmu@126.com
Department of Psychology
Faculty of Aerospace Medicine
Fourth Military Medical University
Xi’an, Shaanxi, China

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RELATED ARTICLE

Effect of Physical Activity on Cognitive Function in Older Adults at Risk for Alzheimer Disease: A Randomized Trial
Nicola T. Lautenschlager, Kay L. Cox, Leon Flicker, Jonathan K. Foster, Frank M. van Bockxmeer, Jianguo Xiao, Kathryn R. Greenop, and Osvaldo P. Almeida
JAMA. 2008;300(9):1027-1037.
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Physical Activity and Cognitive Function in Alzheimer Disease
James A. Mortimer
JAMA. 2009;301(3):272-273.
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Physical Activity and Cognitive Function in Alzheimer Disease—Reply
Nicola T. Lautenschlager, Jianguo Xiao, and Osvaldo P. Almeida
JAMA. 2009;301(3):273-274.
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