Risk Factors and Dementia Cases

Research suggests that a large portion of dementia cases could be prevented, especially among Black and Hispanic adults, who had the highest percentage of combined risk factors, says Medical Express’ recent article entitled “These three risk factors may have the biggest impact on dementia cases.”

"There are things people can do that can raise or lower their individual risk" for dementia, said Mark Lee, a Ph.D. candidate at the University of Minnesota in Minneapolis. He led the study presented Friday at the American Heart Association's Epidemiology and Prevention, Lifestyle and Cardiometabolic Health conference.

As the population ages, the number of dementia cases in the U.S. has been increasing. About 5.8 million U.S. adults currently live with Alzheimer's disease and related dementia. That number is expected to hit 14 million by 2060. The CDC says Black and Hispanic adults will see the largest increases. Among Hispanic adults, cases are expected to rise sevenfold, while cases among aging Black adults are expected to quadruple. These higher rates among Black and Hispanic people may be due to higher rates of heart disease and diabetes, which are linked to dementia risk. Social determinants of health—such as lower levels of education and higher poverty rates—also play a role.

Previous research identified 12 modifiable risk factors believed to be responsible for about 40% of dementia cases worldwide. A 2020 report by The Lancet Commission listed these:

• Lower education level
• Hearing loss
• Traumatic brain injury
• High blood pressure
• Excessive alcohol consumption
• Obesity
• Smoking
• Depression
• Social isolation
• A lack of physical activity
• Diabetes; and
• Air pollution.

In the new study, researchers wanted to see if some risk factors had a greater influence than others on dementia rates—and how that differed among Black, Hispanic, Asian and White adults. When they compiled data from the CDC's National Health and Nutrition Examination Survey and five other datasets, they saw that overall, 42.4% of dementia cases in the U.S. were attributable to the 12 factors. Three heart-related factors were driving most of that risk across races. High blood pressure, also known as hypertension, contributed to 6.7% of those cases; obesity to 7% and physical inactivity to 6.7%.

The percentage of dementia cases attributable to those three risk factors was highest among Black adults. However, the percentage of all 12 risk factors combined was highest among Hispanic people. Asian people had the lowest percentage of combined risk factors. These findings point to the need for better strategies to reduce heart-related risk factors, which would, in turn, reduce dementia risk population-wide. This can, in part, be done through lifestyle changes, combined with medication as needed, said Priya Palta, an assistant professor of medical sciences and epidemiology at Columbia University in New York City.

"Maintaining a cognitively and physically active lifestyle and controlling risk factor levels pharmacologically, when necessary, throughout one's life course is critical for later-life brain health and is likely to impact many of the risk factors examined in this study," said Palta, who was not involved in the research.

Lee said the next step is to see which interventions are most effective for reducing each of the 12 modifiable dementia risk factors. He also said a deeper investigation is required into the social determinants of health underlying racial disparities, such as the disproportionately high rate of hypertension among Black adults.

"That's a really important direction we need to move to if we are serious about achieving equity in health interventions."

Reference: Medical Express (March 6, 2022) “These three risk factors may have the biggest impact on dementia cases”