The Beneficial Effects of Mental and Physical Activity on Cognition on Patients with Alzheimer’s disease (Mark Rapoport, Cedric Gabilondo) May 2014
The Beneficial Effects of Mental and Physical Activity on Cognition in Patients with Alzheimer's disease
Mark J. Rapoport, MD, FRCPC; Associate Professor, Department of Psychiatry, University of Toronto; Staff Psychiatrist, Sunnybrook Health Sciences Centre, Canada
Cedric Gabilondo, MD, Resident, Psychiatry, University of Toronto, Canada
In an earlier Research & Practice column from December 2012, we described some findings about the effects of exercise on depression in later life. Two reports were published earlier this year about the effect of exercise and leisure activities on cognition among patients with a diagnosis of Alzheimer’s disease (AD). The first was a systematic review and meta-analysis of six randomized controlled trials (RCT) that measured the effect of exercise-based interventions on cognitive outcome measures. The second was a cluster-randomized study of leisure activities conducted with 110 participants from nine nursing homes in Hong Kong.
Farina, N., Rusted, J., Tabet, N. The effect of exercise interventions on cognitive outcome in Alzheimer's disease: a systematic review. International Psychogeriatrics. 2014; 26(1): 9-18.
This was a systematic review of RCTs evaluating the efficacy of physical activity interventions in patients with AD. The inclusion criteria stipulated that the interventions
lasted at least four weeks, the intervention was limited to physical activity, there was an objective cognitive measure, and that there were no age or dementia severity limits for the participants. Six studies met the inclusion criteria, and sample sizes ranged from 21 to 40 participants. Physical interventions included walking, stretching, and strength training, among other modalities. A variety of cognitive outcome measures were used. Of the six studies selected, four of them showed statistically significant cognitive improvement in the intervention group relative to control group, and one showed a significant decrease in cognitive decline. The authors then conducted a meta-analysis of four out of the six studies they initially selected, and found a positive effect size of 1.12 (95% CI 0.37-1.88).
Despite the promising results with good quality studies, the variability in the length of the studies (from six weeks to 24 weeks), exercise regimens, and baseline functioning of participants, as well as their small sample sizes preclude firm conclusions. Additionally, the effect size was attenuated to 0.75 (95% CI 0.32-1.17) when the authors dealt with heterogeneity by eliminating an outlier study.
Cheng, S., Chow, P., Song, Y., Yu, E., Chan, A., Lee, T., Lam, J. Mental and Physical Activities Delay Cognitive Decline in Older Persons with Dementia. The American Journal of Geriatric Psychiatry. 2014; 22(1): 63-74.
This study examined the effect of either physical activity (tai chi) or cognitive stimulation (mahjong) on cognitive function in patients with AD. Participants (n=110) were cluster-randomized (based on nursing home) to assess the effect of each these interventions versus control (simple handicrafts). The activities were scheduled for one-hour periods, three times per week for 12 consecutive weeks. The primary outcome was MMSE score, and a variety of secondary outcomes included categorical fluency, digit span, and verbal memory (immediate and delayed recall). The study found that, relative to the control group, the tai chi and mahjong groups had higher MMSE scores after six and nine months from starting the intervention. The difference for the tai chi group was 2.3 (95% CI 0.4-4.2) and 3.7 (95% CI 1.4-6.0) points, at six and nine months respectively. For the mahjong group the difference was 3.0 (95% C: 0.9-5.0) and 4.5 (95% CI 2.0-6.9) points, at six and nine months respectively. With regards to secondary outcomes, mahjong and tai chi improved forward digit span relative to control over time.
It was interesting that the effects on the MMSE only appeared at the six and nine month marks with an intervention that only lasted for three months. There are some limitations to this study because of the lack of blinding, the fact that few participants were on cholinesterase inhibitors, the lack of functional outcome measures, and possible discrepancies in how the interventions were carried out at the different sites. Nonetheless, the authors carefully controlled for confounders including education, APOE, chronic illness, and depression, and they ensured that the findings were robust in a secondary analysis excluding those who were involved in cross-over activities after the active intervention.