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Poor CV fitness, cognitive performance increase early-onset dementia risk
Low CV fitness and poor cognitive performance at age 18 years was associated with increased risk for future early-onset dementia and mild cognitive impairment in a recent population-based cohort study.
Researchers evaluated data from more than 1.1 million Swedish men aged 18 years who underwent conscription exams between 1968 and 2005, with subsequent follow-up for up to 42 years (mean 25.7 years). CV fitness (n=1,174,483) and cognitive performance (n=1,172,190) were assessed during the exams and were linked to hospital registries to determine risk for cognitive impairment and early-onset dementia within this population. CV fitness was evaluated via a cycle ergometer test, and cognitive performance was measured according to logical, verbal, visuospatial and technical cognition.
Participants with low CV fitness or cognitive performance at their conscription exam were at significantly increased risk for early-onset dementia compared with those with high fitness and cognitive performance, after adjustment for confounders (CV fitness: 662 events; HR=2.49; 95% CI, 1.87-3.32; cognitive performance: 657 events; HR=4.11; 95% CI, 3.19-5.29). Participants with low fitness and cognitive performance also were at increased risk for early-onset mild cognitive impairment (CV fitness: 213 events; HR=3.57; 95% CI; 2.23-5.74; cognitive performance: 212 events; HR=3.23; 95% CI, 2.12-4.95). Exclusion of patients with psychiatric or neurological symptoms or disorders at baseline or within 20 years of conscription did not significantly alter results.
A combination of poor CV fitness and cognitive performance further increased the risk for early-onset dementia and mild cognitive impairment (HR=7.34; 95% CI, 5.08-10.58 for dementia; HR=8.44; 95% CI, 4.64-15.37 for mild cognitive impairment). The researchers noted that high CV fitness reduced the risk for early-onset dementia by 48% among those with low cognitive performance, whereas high cognitive performance reduced the risk for dementia by 74% among those with low CV fitness.
Adjustment for cerebrovascular disease attenuated the association between CV fitness and early-onset dementia, and adjustment for diabetes also slightly attenuated this association. The association between cognitive performance and dementia was not attenuated by adjustment for cerebrovascular disease, diabetes or hypertension, nor was the link between early-onset mild cognitive impairment and either CV fitness or cognitive performance.
“These results highlight the importance of CV fitness, independent of a cognitive performance, and it would be of interest to target high-risk groups with low cognitive performance for intervention with CV training,” the researchers wrote. “A greater understanding of the mechanisms underlying these associations is needed to increase opportunities and strategies for prevention.”
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