Cycling in Midlife Tied to Lower Risk of Dementia

Using physically active transportation modes in midlife —
particularly cycling — was tied to lower dementia risk and greater
hippocampal volume, a large U.K. Biobank study suggested.

Compared with non-active travel like driving or public
transportation, travel that incorporated cycling was associated with a
lower adjusted risk of all-cause dementia over 13 years (HR 0.81, 95% CI
0.73-0.91), reported Liangkai Chen, PhD, of Huazhong University of
Science and Technology in Wuhan, China, and co-authors.

Risk
was lower for three forms of dementia: Alzheimer’s disease (HR 0.78,
95% CI 0.66-0.92), young-onset dementia (HR 0.60, 95% CI 0.38-0.95), and
late-onset dementia (HR 0.83, 95% CI 0.75-0.93), the researchers wrote
in JAMA Network Open.

Transportation that involved cycling — either cycling alone, or
cycling mixed with another transportation mode — was significantly
associated with a higher hippocampal volume (β=0.05, 95% CI 0.02-0.08).
The APOE4 allele modified associations between travel modes and all-cause dementia (P=0.02 for interaction) and late-onset dementia (P=0.04 for interaction).

“Our findings suggest that active travel modes, particularly cycling
and mixed-cycling, are associated with higher hippocampal volumes. The
hippocampus is critical for memory and cognitive function, and greater
volume is generally considered a sign of better brain health,” Chen
noted.

“This outcome could be attributed to the physical activity and
aerobic exercise involved in cycling, which is known to have
neuroprotective effects,” Chen wrote in an email to MedPage Today.
“Cycling, especially as a regular form of transport, may help increase
blood flow to the brain, reduce inflammation, and stimulate
neurogenesis, and requires higher cognitive engagement during travel,
which could all contribute to the observed preservation of hippocampal
volume.”

The gene-environment interaction is a key finding, Chen observed. “Individuals without the APOE4
gene variant appeared to derive greater benefits from active travel
modes in terms of dementia risk reduction. Critically, however, our data
indicate that APOE4 carriers can still benefit from cycling,
though these benefits are likely attenuated due to the allele’s strong
biological influence on neurodegeneration pathways,” he pointed out.

“These results collectively suggest that promoting active travel,
particularly cycling, remains a valuable public health strategy to
enhance brain health across populations,” he said.

Various travel modes involve different attention engagement and
spatial navigation abilities. A recent study of workers in hundreds of
occupations found that those who used real-time spatial and navigational
processing skills the most — notably, taxi and ambulance drivers — had the lowest proportion of deaths due to Alzheimer’s disease.

Whether the aerobic effects of indoor cycling can curb the effects of Alzheimer’s disease in APOE4 carriers is being studied at the Cleveland Clinic in the CYCLE-AD trial. Early reports showed that sedentary APOE4 carriers experienced more significant declines in episodic memory and hippocampal volume than APOE4
carriers who engaged in moderate physical activity, suggesting that
activities like indoor cycling may enhance the functional and structural
integrity of the hippocampus in this group.

Chen and colleagues assessed data from 479,723 U.K. Biobank participants with an average baseline age of 56.5 years. More than half
(54.4%) were women; all were dementia-free at baseline and able to
walk. Over 85% were of European ancestry.

The researchers assessed travel modes by asking about transportation
modes that participants used most often in the past 4 weeks, not
including work commutes. Responses were grouped into four categories:
non-active (car or public transportation), walking, mixed-walking (a
combination of non-active and walking), and cycling and mixed-cycling
(cycling combined with other modes).

Nearly half of the study population (49.1%) were inactive; 6.8% were
classified as walking-only, 37% as mixed-walking, and 7% as cycling and
mixed-cycling.

Over a median follow-up of 13.1 years, 8,845 cases of dementia and
3,956 cases of Alzheimer’s disease were recorded. While participants in
the mixed-walking group had a lower risk of all-cause dementia compared
with those in the inactive group (HR 0.94, 95% CI 0.89-0.98), other
results for walking were mixed.

“Overall,
the association of walking with brain health remains inconsistent and
warrants further investigation,” Chen and colleagues wrote. “Our results
suggest that mixed-walking models, which combine walking with other
forms of travel that require higher cognitive engagement (e.g.,
driving), may be more beneficial in reducing dementia risk than walking
alone.”

The study was observational and causal relationships cannot be
determined. Transportation modes were self-reported, and racial and
ethnic diversity in the U.K. Biobank sample was limited, the researchers
acknowledged.