The Mental Activity and eXercise (MAX) trial: a randomized controlled trial to enhance cognitive function in older adults

Abstract

Importance: The prevalence of cognitive impairment and dementia are projected to rise dramatically during the next 40 years, and strategies for maintaining cognitive function with age are critically needed. Physical or mental activity alone result in relatively small, domain-specific improvements in cognitive function in older adults; combined interventions may have more global effects.

Objective: To examine the combined effects of physical plus mental activity on cognitive function in older adults.

Design: Randomized controlled trial with a factorial design.

Setting: San Francisco, California.

Participants: A total of 126 inactive, community-residing older adults with cognitive complaints.

Interventions: All participants engaged in home-based mental activity (1 h/d, 3 d/wk) plus class-based physical activity (1 h/d, 3 d/wk) for 12 weeks and were randomized to either mental activity intervention (MA-I; intensive computer) or mental activity control (MA-C; educational DVDs) plus exercise intervention (EX-I; aerobic) or exercise control (EX-C; stretching and toning); a 2 × 2 factorial design was used so that there were 4 groups: MA-I/EX-I, MA-I/EX-C, MA-C/EX-1, and MA-C/EX-C.

Main outcome measures: Global cognitive change based on a comprehensive neuropsychological test battery.

Results: Participants had a mean age of 73.4 years; 62.7% were women, and 34.9% were Hispanic or nonwhite. There were no significant differences between the groups at baseline. Global cognitive scores improved significantly over time (mean, 0.16 SD; P < .001) but did not differ between groups in the comparison between MA-I and MA-C (ignoring exercise, P = .17), the comparison between EX-I and EX-C (ignoring mental activity, P = .74), or across all 4 randomization groups (P = .26).

Conclusions and relevance: In inactive older adults with cognitive complaints, 12 weeks of physical plus mental activity was associated with significant improvements in global cognitive function with no evidence of difference between intervention and active control groups. These findings may reflect practice effects or may suggest that the amount of activity is more important than the type in this subject population.

Trial registration: clinicaltrials.gov Identifier: NCT00522899.

Figure 1

Mental Activity and eXercise (MAX) Trial Design. The MAX Trial used a 2×2 factorial design in which subjects were first randomized to either the mental activity intervention (MA-I: intensive computer training) or mental activity control (MA-C: educational DVD) group and then to the exercise intervention (EX-I: aerobic) or exercise control (EX-C: stretching/toning) group. This design enables comparisons to be made between the mental activity groups (ignoring exercise) and between the exercise groups (ignoring mental activity) and also to assess for evidence of interaction between mental activity and exercise.

Figure 2

Flow Chart

Figure 3. Impact of Intervention on Composite Cognitive Score

For the primary outcome of change on the composite cognitive score, scores improved significantly over time but did not differ between the MA-I and MA-C groups, EX-I and EX-C groups or all 4 randomization groups.

Figure 4. Change in Individual Cognitive Tests

Cognitive function improved significantly (p<0.05) for the Digit Symbol Substitution Test (DSST), Trails A, Eriksen Flanker Test (EFT) congruent and incongruent tests, and Useful Field of View divided attention (UFOV-DA) and selective attention (UFOV-SA), and composite score. Improvements were of borderline statistical signficance (p<.10) for Rey Auditory Verbal Learning Test total words learned (RAVLT-lrn), Trails B, and UFOV processing speed (UFOV-PS).

Figure 5. Comparison of Mental Activity Intervention (MA-I) versus Mental Activity Control (MA-C) Groups in Subjects With Normal Memory and Low Memory

Figure 5 show the three-way interaction between baseline memory, mental activity group and time and raises the possibility that the mental activity intervention (MA-I) training may have led to greater cognitive improvements than the mental activity control (MA-C) training in subjects with low memory at baseline, although the interaction and the between-group effects were both of borderline statistical significance.