Patients with a greater burden of modifiable vascular risk factors in midlife could live fewer years without dementia compared with those with no vascular risk factors.

Investigators analyzed data from the Atherosclerosis Risk in Communities Neurocognitive Study, a community-based prospective cohort that enrolled participants from four US communities. The analysis included 12,409 patients who were alive and free of dementia at 55 years and had midlife assessments of diabetes, hypertension, and smoking status between 1990 and 1992. The participants were followed through 2022, during which 3,008 of them developed dementia and 5,238 died without dementia. Outcome measures included dementia-free survival from 55 to 95 years, estimated while accounting for mortality prior to dementia as a competing event, as well as incident dementia, dementia-free mortality, postdementia survival. Subgroup analyses were conducted by sex, race, and apolipoprotein E epsilon 4 status.

Dementia-free survival declined progressively as the vascular risk burden increased. Patients with no vascular risk factors were estimated to live 30.1 years free of dementia compared with 26.3 years among those with one risk factor, 21.0 years among those with two, and 17.5 years among those with all three.

Compared with the patients with no vascular risk factors, those with all three risk factors had 2.69 times the likelihood of developing dementia 5.61 times the likelihood of experiencing mortality without dementia and lived an estimated 12.6 fewer years without dementia between 55 and 95 years.

The association between vascular risk burden and shorter dementia-free survival was consistent across subgroup analyses. Female participants had longer dementia-free survival compared with male participants at each level of vascular risk. Black patients had fewer dementia-free years compared with White patients, and those carrying the apolipoprotein E epsilon 4 allele had shorter dementia-free survival than noncarriers.

The investigators reported that although patients with more vascular risk factors developed dementia at younger ages, their cumulative incidence of dementia by 95 years was lower compared with that of patients with no vascular risk factors because more patients died prior to developing dementia.

The study had several limitations. Vascular risk factors were measured just once in midlife, preventing assessment of changes over time. Dementia ascertainment may have differed between participants who attended in-person follow-up visits and those identified through surveillance methods. Residual confounding could not be excluded, and the findings did not establish a causal relationship between vascular risk burden and dementia-free survival.

"Expressing vascular risk in time-based terms offers a clear, patient-centered framework to motivate prevention strategies that preserve both cardiovascular and cognitive health," wrote lead study author Jiaqi Hu, of the School of Healthcare Management at Tsinghua Medicine at Tsinghua University in China, and colleagues.

The study authors reported no relevant disclosures.

Source: Neurology Open Access