Dementia Risk: Avoiding 3 Midlife Problems May Add Years of Brain Health

People who avoid smoking, diabetes, and high blood pressure during midlife may spend significantly more years living without dementia, according to a long-term study that followed more than 12,000 adults for more than two decades. Researchers found that people with none of the three risk factors had about 13 more years of dementia-free survival than those who had all three.

The findings, published in Neurology Open Access, add to growing evidence that brain health is closely connected to cardiovascular health. The study does not show that avoiding these conditions will guarantee an additional 13 dementia-free years for an individual, but it suggests that managing these risks earlier in life may influence how long people remain free of cognitive impairment.

What the Long-Term Study Found

Researchers analyzed data from 12,409 participants in the Atherosclerosis Risk in Communities study, which began in 1987. Participants were middle-aged when the study began, with an average age of about 56, and none had dementia at the start.

The researchers focused on three factors that could be measured consistently across the study: high blood pressure, diabetes and smoking. Participants were then followed for a median of 26.3 years, with researchers tracking dementia diagnoses and deaths.

During the follow-up period, 3,008 participants developed dementia, while 5,238 died without developing the condition.

The difference in dementia-free survival was substantial. People who had none of the three risk factors were estimated to live about 30.1 years without dementia, compared with 17.5 years among those who had all three. That represents a difference of about 12.6 years, often rounded to 13 years.

The researchers also found a stepwise pattern. Having one of the risk factors was associated with about 26.3 years of dementia-free survival, while having two was associated with about 21 years.

Josef Coresh, senior investigator of the study and founding director of the Optimal Aging Institute at NYU Langone, said the findings show that vascular health in midlife can affect a person’s aging trajectory.

Why Heart Health Matters for the Brain

The study did not investigate exactly why these three conditions were associated with fewer dementia-free years. But researchers say there are several biological reasons the connection may exist.

High blood pressure, diabetes and smoking can damage blood vessels throughout the body, including the small vessels that supply the brain. Damaged vessels can reduce the delivery of oxygen and nutrients to brain tissue and interfere with the removal of waste products.

Blood vessel damage can also trigger inflammation. Over time, these changes may contribute to conditions that make the brain more vulnerable to cognitive decline.

Coresh said vascular damage can affect the brain because it can result in “fewer nutrients into the brain and poorer clearance of toxins out of the brain.”

The researchers also noted that vascular disease may contribute to the accumulation of Alzheimer’s-related proteins such as amyloid in the brain, potentially adding another pathway through which cardiovascular problems could affect cognitive health.

But the study cannot establish that these mechanisms caused the dementia outcomes. It was an observational analysis, meaning researchers identified associations rather than proving cause and effect.

The Three Midlife Risks to Watch

The three factors examined in the study are common health problems that can often be managed or prevented.

High blood pressure: Persistent hypertension can damage blood vessels and increase the risk of stroke and other cardiovascular problems. Monitoring blood pressure and addressing elevated readings with lifestyle changes or medical treatment can help protect vascular health.

Diabetes: Diabetes, particularly Type 2 diabetes, can affect blood vessels and contribute to cardiovascular disease. The researchers’ findings suggest that preventing or delaying diabetes during midlife may be important for long-term brain health.

Smoking: Smoking damages blood vessels and is a major cardiovascular risk factor. Avoiding smoking or quitting can therefore have benefits that extend beyond the lungs.

Each additional risk factor was associated with fewer expected years of life without dementia. The researchers said the results highlight the importance of addressing vascular risks before older age.

Dung Trinh, an internist at MemorialCare Medical Group who was not involved in the study, said the findings reinforce the relationship between cardiovascular and brain health.

“High blood pressure, diabetes, and smoking can damage blood vessels, increase inflammation, and reduce the brain’s resilience over time,” Trinh said.

The 13-Year Figure Needs Context

The 13-year difference should not be interpreted as a promise that a person who avoids these three conditions will automatically delay dementia by exactly 13 years.

The researchers measured the risk factors only at the beginning of the study. They could not fully account for changes that happened later, such as someone developing diabetes, developing high blood pressure, starting to smoke, or quitting smoking.

The analysis also did not include every factor that can influence dementia risk.

Trinh said the study “cannot prove that avoiding these conditions will give an individual exactly 13 additional dementia-free years.” He noted that the calculation compares people with none of the three risk factors with those who had all three, while dementia-free survival also reflects overall longevity.

Other differences emerged among participants. Women generally lived longer without dementia than men, while Black participants tended to have fewer dementia-free years than White participants. Genetic factors also influence dementia risk, including the APOE-e4 variant.

Age remains the strongest known risk factor for dementia, and not every case can be prevented.

Other Ways to Protect Brain Health

The three factors in the study are only part of a much larger group of potentially modifiable dementia risks.

Researchers and health organizations have also identified physical inactivity, unhealthy diet, high cholesterol, obesity, hearing and vision loss, depression, social isolation, excessive alcohol consumption, traumatic brain injury, and air pollution as factors that may influence dementia risk.

The World Health Organization’s updated guidance on dementia risk also emphasizes managing conditions such as hypertension and diabetes and avoiding smoking.

Coresh recommends starting cardiovascular risk management early rather than waiting until health problems become established.

“Know your blood pressure and A1c by your 40s, and aim to prevent rather than only treat,” Coresh advised, pointing to physical activity, lower salt intake and weight control as ways to help prevent rising blood pressure. He also emphasized delaying the onset of diabetes and avoiding smoking.

The broader message from the research is that dementia risk is influenced by health across the life course. Maintaining cardiovascular health during the 40s, 50s and 60s may provide an opportunity to preserve both longevity and cognitive health, although it cannot eliminate the possibility of dementia.