A group of sedentary older adults with complaints of memory impairment experienced enhanced cognitive function after a 12-week program of mental and physical activity. Members of a control group who did not engaged in such activity also showed the same degree of improvement, according to results reported online April 1 in JAMA Internal Medicine.

These findings suggest that the amount of activity may be more important than the type of activity in improving cognitive function, since all the study groups participated in some form of activity for 60 minutes per day, 3 days per week, for 12 weeks, said Deborah E. Barnes, Ph.D., of the department of psychiatry and the department of epidemiology and biostatistics, University of California, San Francisco, and her associates.

Or the results may simply indicate that repeated testing of cognitive function itself improves performance on those tests, the investigators noted.

Dr. Barnes and her colleagues assessed four combinations of cognitive and physical activity in 126 community-dwelling people aged 65 years and older (mean age, 73 years) who had normal cognition but who reported that their memory or thinking skills had worsened recently. These subjects had relatively high global cognitive function, in line with their relatively high educational attainment.

Approximately 56% of the study population had hypertension, 14% had diabetes, 9% had a history of MI, and half were either past or current smokers.

The participants were randomly assigned to receive a home-based intensive mental activity or a home-based control mental activity, plus a group intensive exercise intervention or a group control intervention.

The mental-activity intervention was a series of computer games that enhanced both speed and accuracy of visual and auditory processing. The games increased in difficulty as subjects' performance improved. For the control mental activity, participants individually viewed videos of educational lectures on art, history, and science.

The exercise intervention included 30 minutes of intensive aerobic exercise, whereas the control "exercise" substituted 30 minutes of stretching and toning that didn't raise the heart rate above resting level.

The primary outcome measure was change in cognitive function at week 12, as assessed by a battery of neuropsychological tests of verbal learning and memory, verbal fluency, processing speed, executive function, reaction times, "visuospatial" function, and attention. All the study participants showed significant improvement on this measure during the study period, but there were no significant differences between the intervention groups and the control groups, the investigators said (JAMA Intern. Med. 2013 April 1 [doi:10.1001/jamainternmed.2013.189]).

To assess the possibility that this result was because of practice effects from repeated cognitive testing, an additional 12 participants were enrolled in a post hoc study in which there were no interventions; the subjects simply underwent the same battery of neuropsychological tests after a 12-week interval. Scores improved in these subjects, "suggesting that some, but not all, of the improvements observed may have been due to repeated testing" itself, Dr. Barnes and her associates said.

"It is possible that our 12-week intervention was not long enough or intense enough to achieve a substantially greater aerobic response in the intervention group, and that a difference between the groups would have emerged in a longer study," they added.

A total of 26 participants withdrew from the study because of illness, physical inability to perform the activities, time constraints, or miscellaneous reasons. Another nine withdrew after experiencing an adverse event that may have been related to the study activity, such as dizziness, pain, falls, and pulmonary edema. Thus, the attrition rate was 28%.

This study was funded by the National Institute on Aging, the Alzheimer's Association, the University of California, and the National Center for Research Resources. None of the investigators reported having any relevant financial conflicts of interest.

Commentary - Negative results, positive message

Dr. Nicola T. Lautenschlager and Kay L. Cox, Ph.D., comment: The overall results of the trial by Barnes et al. were negative, but "there is still a positive message and several points that can be learned from the findings," said Dr. Lautenschlager and Dr. Cox.

The investigators showed that stimulating activity, whether mental or physical, can significantly improve cognition in only 12 weeks, "even in older adults with cognitive complaints." They also suggested that interventions of longer duration might lead to a larger discrepancy in results between the intervention and the control participants.

This trial also demonstrated that "inactive older adults can be motivated to become more active," at least for 12 weeks. Future research should examine how to achieve even longer-term behavioral change, Dr. Lautenschlager and Dr. Cox said.

Dr. Lautenschlager is in the academic unit for psychiatry of old age at St. Vincent's Health; the department of psychiatry at the University of Melbourne (Australia); and the School of Psychiatry and Clinical Neurosciences at the University of Western Australia, Perth. Dr. Cox is with the University of Western Australia School of Medicine and Pharmacology, Perth. They reported no financial conflicts of interest. These remarks were taken from their invited commentary accompanying Dr. Barnes' report (JAMA Intern. Med. 2013 April 1 [doi:10.1001;jamainternmed.2013.206]).

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