Staying Active in Body and Mind May Slow Brain Metabolic Decline, but the Effects Are Small
In 1,176 older adults, more physical and cognitive activity tracked with slower brain glucose decline; cognitive activity also with less amyloid rise. Effects were small.
Resumen
Researchers in the Mayo Clinic Study of Aging asked whether physical and mentally stimulating activities relate to how Alzheimer's brain-imaging markers change over time. They followed adults aged 50+ who were cognitively unimpaired or had mild cognitive impairment, using amyloid PET, tau PET and FDG-PET (glucose metabolism). People reporting more total or moderate-to-vigorous physical activity showed a slower decline in brain glucose metabolism. Those reporting more cognitive activity showed both slower metabolic decline and a smaller increase in amyloid. No link emerged with tau accumulation. The effects were small and may not be clinically meaningful, and the observational design cannot establish cause and effect.
Resumen detallado
Physical and mentally stimulating activities are linked to lower risk of mild cognitive impairment and dementia, but evidence on whether they influence Alzheimer's disease (AD) brain pathology in people is inconsistent. Animal studies suggest benefits for amyloid and tau, while human imaging studies have been mixed and often small. This study aimed to test the question in a larger, population-based sample using repeated brain scans.
Using the population-based Mayo Clinic Study of Aging in Olmsted County, Minnesota, the researchers included adults aged 50 or older who were cognitively unimpaired (about 90%) or had MCI (about 10%). Participants reported their activities over the 12 months before baseline. Physical activity was scored in metabolic equivalents (MET) multiplied by weekly frequency, giving a total physical activity score and a moderate-to-vigorous physical activity (MVPA) score. Cognitive activity combined the weekly frequency of ten activities, such as reading, games, music, computer use, crafts and social activities. Participants had amyloid PET (PiB, in centiloids), tau PET (flortaucipir SUVR) and FDG-PET (glucose metabolism) at baseline, and about half had follow-up scans. Samples were 1,176 for amyloid, 399 for tau and 983 for FDG-PET, with mean follow-up of 1.3 to 3.4 years. Linear mixed-effects models adjusted for age, sex, APOE ε4 status and comorbidity (plus education for cognitive activity) tested whether baseline activity scores changed biomarker slopes.
Amyloid and tau increased and glucose metabolism fell over time, as expected. Higher total physical activity (interaction estimate 0.0017; p=0.021) and higher MVPA (0.0015; p=0.040) were associated with a less pronounced FDG-PET decline. For example, average annual FDG-PET decline was 0.0116 SUVR units, versus about 0.0099 for those one SD above average physical activity. Higher cognitive activity was associated with a smaller rise in amyloid (−0.2253 centiloids per year per SD; p=0.043) and a smaller FDG-PET decline (0.0015; p=0.038). There were no significant associations with tau PET. Baseline cognitive status (unimpaired vs MCI) did not modify the associations.
The findings suggest that an active lifestyle, both physical and mental, may be modestly linked to preserved synaptic function, and mental engagement to slightly slower amyloid accumulation. The authors themselves note the effects were small and possibly not clinically meaningful, so these results support, rather than prove, lifestyle's role in brain health.
Caveats include self-reported activity measured only once at baseline, short follow-up (especially for tau PET, 1.3 years), only about half the sample having follow-up scans, and a single-site, largely well-educated community cohort. Observational design means causality and reverse causation cannot be excluded, and multiple models were run without evident correction for multiple comparisons, so borderline p-values warrant replication.
Hallazgos clave
- Higher total physical activity and MVPA were each linked to a less pronounced decline in FDG-PET glucose metabolism over time (p=0.021 and p=0.040).
- Higher cognitive activity was associated with a smaller increase in amyloid PET (−0.23 centiloids per year per SD; p=0.043).
- Cognitive activity was also linked to slower FDG-PET decline, suggesting less synaptic dysfunction (p=0.038).
- No significant associations were found between either activity type and tau PET trajectories.
- Effect sizes were small: average annual FDG decline of 0.0116 versus 0.0099 SUVR at +1 SD physical activity.
Metodología
Longitudinal analysis within the population-based Mayo Clinic Study of Aging of adults aged 50+ who were cognitively unimpaired or had MCI (n=1,176 amyloid, 399 tau, 983 FDG-PET). Self-reported physical (MET-based total and MVPA scores) and cognitive activity over the prior 12 months were related to PET biomarker slopes using linear mixed-effects models adjusted for age, sex, APOE ε4, comorbidity and, for cognitive activity, education.
Limitaciones del estudio
Activity was self-reported at baseline only, follow-up was short (1.3 years for tau PET) with only about half of participants rescanned, and the observational design cannot establish causality or exclude reverse causation. Effects were small, p-values were borderline without clear multiple-comparison correction, and the largely educated, single-region cohort may limit generalizability.
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