Study links diabetes, smoking and hypertension to earlier onset of dementia
Researchers found that middle-aged adults with type-2 diabetes, high blood pressure and a history of smoking develop dementia up to 13 years earlier than those without these risk factors.
A new analysis of more than 12,400 participants in the long-running Atherosclerosis Risk in Communities study suggests that having type-2 diabetes, hypertension and a smoking habit around age 56 more than doubles the likelihood of developing dementia and increases the risk of premature death. Those without any of the three conditions averaged 30.1 dementia-free years, compared with 17.5 years for those with all three, indicating a potential delay of nearly 13 years if the risk factors are avoided.
The findings, published in Neurology Open Access, are based on a single baseline measurement of the three vascular risk factors and a median follow-up of about 26 years. Researchers caution that the results show association, not causation, and that participants’ health status could have changed during the study period.
"That’s relatively easy for clinicians to discuss and patients to understand," said Dr. Josef Coresh, senior author and director of the Optimal Aging Institute at NYU Grossman School of Medicine. He added that quantifying potential extra “good years” may motivate lifestyle changes more effectively than presenting a percentage risk.
Experts not involved in the study highlighted the broader implications. Dr. Sanjula Singh of Harvard Medical School described the results as an "important estimate rather than an exact prediction for every individual." Cardiologist Dr. Andrew Freeman called the research "really exciting" but emphasized the need for continued public-health efforts to promote healthier living.
The study reinforces existing guidance that managing blood pressure, controlling blood sugar and quitting smoking can reduce dementia risk. Recommendations include adopting a lower-fat, plant-based diet such as the DASH plan, regular physical activity, adequate sleep, stress management and using proven cessation aids when quitting smoking. About 45% of dementia cases are attributed to modifiable risk factors, according to Dr. Singh.
Women in the cohort remained dementia-free slightly longer than men, while Black participants developed dementia earlier than White participants, a disparity linked to higher rates of the risk factors and lower socioeconomic indicators. Researchers noted that the three vascular conditions can damage blood vessels throughout the body, including those supplying the brain, thereby increasing vulnerability to cognitive decline.