Longer, Less Fragmented Physical Activity Bouts Linked to Lower Future Dementia, Depression, and Anxiety Risk
核心洞察
A UK Biobank study of 66,483 adults found longer moderate-to-vigorous physical activity bouts and less fragmented activity were each associated with significantly lower future risk of dementia (搜索), depression (搜索), and anxiety (搜索).
Compared with the highest activity fragmentation, the lowest fragmentation was linked to an 82%, 57%, and 52% lower risk of dementia (搜索), depression (搜索), and anxiety (搜索), respectively.
Neuroimaging in 13,108 participants showed prolonged activity bouts and lower fragmentation correlated with greater hippocampal volume and lower white matter hyperintensity volume.
A large multimodal UK Biobank study suggests that how adults accumulate daily movement—not only how much they do—may be relevant to future brain and mental health. Published in the journal Translational Psychiatry, the study found that longer bouts of moderate-to-vigorous physical activity and less fragmented activity were each associated with a significantly lower risk of future inpatient diagnoses of dementia (搜索), depression (搜索), and anxiety (搜索).
Researchers at the City University of Hong Kong analyzed accelerometer-measured data on the longest daily active-intensity bout duration, moderate-to-vigorous physical activity (MVPA) bout duration, and activity fragmentation collected from 66,483 UK Biobank participants. Activity fragmentation measured how frequently an active minute was followed by sedentary time, with higher fragmentation indicating shorter, more intermittent activity patterns. Associations with future inpatient diagnoses were assessed after adjustment for potential confounding factors, including total physical activity.
Key Findings on Bout Duration and Fragmentation
The analysis revealed that longer active-intensity bouts were associated with a lower risk of subsequent dementia (搜索) and anxiety (搜索), whereas longer MVPA bouts and less fragmented activity patterns were associated with a lower risk of all three outcomes, irrespective of total daily physical activity duration.
Compared with the shortest observed active bouts, which lasted two minutes, bouts lasting 47 minutes were associated with the lowest observed risk of dementia (搜索). Compared with participants who recorded no MVPA, bouts lasting 13 minutes were associated with the lowest observed risk of dementia, while bouts lasting 36 minutes were associated with the lowest observed risk of depression (搜索) and anxiety (搜索).
Compared with the highest observed activity fragmentation, the lowest observed fragmentation was associated with an 82%, 57%, and 52% lower risk of dementia (搜索), depression (搜索), and anxiety (搜索), respectively.
Brain Structural Associations
Neuroimaging data from a subgroup of 13,108 participants revealed that prolonged MVPA bouts and lower fragmentation were associated with greater left hippocampal volume and lower white matter hyperintensity volume. Longer MVPA bouts were also associated with greater right hippocampal volume, while lower fragmentation was associated with greater total brain volume. The authors note that these cross-sectional analyses cannot determine whether activity patterns caused these structural differences.
APOE4 Genotype and Dementia Risk
Among participants carrying the apolipoprotein E ε4 (APOE4) (搜索) allele, which is associated with increased dementia (搜索) risk, dementia risk progressively decreased as activity fragmentation decreased. This suggests that fragmented activity patterns may serve as a novel target for reducing dementia risk among individuals who are genetically predisposed. However, the authors caution that this association does not establish that reducing fragmentation will reduce dementia risk.
Study Significance and Proposed Implications
Given the findings, the researchers hypothesized that prolonged physical activity may be more effective than fragmented activity in improving cardiorespiratory fitness and reducing neuroinflammation, which in turn may reduce dementia (搜索) risk. For depression (搜索) and anxiety (搜索), they highlighted the need for more evidence to gain insight into possible biological mechanisms.
Existing evidence on non-biological mechanisms indicates that prolonged high-intensity physical activity may support mental health through improved self-efficacy, resilience, and self-esteem, and that prolonged aerobic activity may improve mental health through socialization.
The researchers suggest that middle-aged and older adults should be encouraged to undertake daily bouts of MVPA lasting 36 minutes, corresponding to more than 250 minutes of MVPA per week and satisfying the WHO's physical activity guidelines. This is an author-proposed public-health implication rather than a recommendation established by causal evidence. Active-intensity bouts may serve as an alternative strategy for individuals unable to perform MVPA, though they may require a greater time commitment to achieve beneficial dementia (搜索) outcomes and were not significantly associated with a lower risk of depression (搜索).
Limitations
The study has several limitations. Although the researchers excluded diagnoses occurring within the first two years and adjusted for baseline cognition and mental health measures, preclinical disease and reverse causation cannot be ruled out. The largely White UK Biobank cohort may limit generalizability, and accelerometer thresholds may not capture all forms of activity, including strength training. As an observational study, it cannot establish cause and effect.