High blood pressure, diabetes, and smoking during middle age may be linked to substantially fewer years of life without dementia, according to a new study.
Researchers found that people who had none of the three risk factors lived nearly 13 years longer without dementia, on average, than those who had all three.
The study, led by researchers at NYU Langone Health, was published Aug. 5 in Neurology Open Access.
Researchers analyzed data from 12,409 participants in the Atherosclerosis Risk in Communities Study. The long-running project began in 1986 and tracked adults from several U.S. communities for decades.
Participants in the new analysis had an average age of 56 and did not have dementia when tracking began. Researchers assessed whether they had high blood pressure, diabetes or smoked.
They were then followed for an average of about 26 years. During that period, 3,008 participants developed dementia and 5,238 died without developing the condition.
People with none of the three risk factors lived an average of about 30 years without dementia from the start of the study. Those with all three lived about 17 years dementia-free.
CNN reported that participants who had all three factors in midlife were more than twice as likely to develop dementia and more than five times as likely to die prematurely from another cause.
“Our findings argue that people need to actively avert these factors in midlife as a strategy for preserving brain health for more than a decade,” said Dr. Josef Coresh, the study’s senior investigator and founding director of NYU Langone’s Optimal Aging Institute.
The study also found differences by sex and race.
Women with all three risk factors lived an average of 18.1 years without dementia after tracking began, compared with 16.6 years for men. White participants with all three factors lived an average of 19.6 dementia-free years, compared with 16 years for Black participants.
By age 85, only 7 percent of participants with all three risk factors remained dementia-free, compared with 35 percent of those who had none, according to CNN.
Researchers said several factors could contribute to those differences. Participants with poorer health profiles were also more likely to have a higher body mass index, a history of stroke, lower physical activity and lower educational attainment. They were also more likely to carry the APOE ε4 gene, a major genetic risk factor for Alzheimer’s disease.
High blood pressure, diabetes and smoking can damage blood vessels, including those supplying the brain. That damage can reduce the delivery of oxygen and nutrients and increase the risk of stroke and small vessel disease, according to Dr. Jacqui Hanley of Alzheimer’s Research UK, who was not involved in the research.
The researchers cautioned that the study found an association and did not prove that avoiding the three risk factors directly caused people to remain dementia-free longer.
The risk factors were also measured only once before the long follow-up period, meaning changes in participants’ health and behavior over time were not fully captured.