Older adults on average exhibit signs of mild cognitive impairment compared to younger adults. It is not clear how much of this normal decline in memory and cognitive functioning is inevitably due to aging, and how much might be counteracted by healthy lifestyle changes.
Lenze et al. [JAMA] conducted a large-scale, multi-site, randomized, controlled trial to test whether mindfulness meditation and/or daily exercise could reduce cognitive impairment in older adults compared to an active control group. Prior studies had shown some support for both types of intervention, and many health experts recommend exercise to counteract cognitive impairment.
The researchers randomized 585 older adults with subjective mental decline but without dementia (average age = 71 years; 72% female; 82% Caucasian) to Mindfulness-Based Stress Reduction (MBSR), an exercise group, MBSR + exercise, or a health education control. MBSR was delivered in the standard 8-week plus half-day retreat format.
After the initial eight week course, participants received monthly booster classes for the remaining 16 months of the study. The program encouraged 60 minutes of daily home meditation practice throughout the length of the study.
The exercise program focused on aerobic exercise, resistance training, and functional exercises. The program met for two 1.5 hour classes weekly for the first six months, and then once weekly for the remaining 12 months of the study. A combined total of 300 minutes of exercise per week was recommended. Participants in the combined MBSR+exercise group participated in both full programs simultaneously.
The health education control met for the same session length and frequency as the MBSR group and offered a didactic curriculum focused on leading a healthy lifestyle.
Participants were assessed at baseline and 6- and 18-month follow-up on a neuropsychological battery assessing memory and cognitive functioning as well as measures of functioning in activities of daily life and quality of life. Participants had structural MRIs taken of hippocampal volume and dorsolateral pre-frontal cortex (dlPFC) surface area and cortical thickness.
Additionally, participants were assessed on measures of physical health and fitness including aerobic fitness, insulin sensitivity, body fat, plasma cortisol, sleep quality, and body strength. Retention in the trial was good, with 97% of participants completing the 6-month assessment and 81% completing the 18-month assessment.
The results showed no significant differences between study groups on memory and cognitive function at either 6- or 18-month follow-up. All groups showed a reduction in hippocampal volume and dlPFC surface area and cortical thickness at 18 months consistent with normal atrophy due to aging.
Contrary to expectation, the reduction in hippocampal volume was significantly greater in the MBSR group. Only the exercise groups showed significant improvement in aerobic fitness, physical strength, and sleep quality over time.
The study showed that, relative to a health education curriculum, neither mindfulness nor exercise improved memory or cognitive functioning or slowed brain tissue atrophy in this cohort of older adults with subjective cognitive complaints. The study participants were mostly college educated, Caucasian females with no evidence of dementia, and these findings may not generalize to clinical populations.
Lenze, E. J., Voegtle, M., Miller, J. P.,... Wetherell, J. L. (2022). Effects of Mindfulness Training and Exercise on Cognitive Function in Older Adults: A Randomized Clinical Trial. JAMA, 328(22), 2218–2229.
Link to study