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Young adults with higher levels of inflammation may face diminished cognitive function in midlife, according to a new study by researchers at UC San Francisco. This inflammation, often linked to obesity, physical inactivity, chronic illness, stress, and smoking, has now been connected to lower cognitive abilities later in life.
Previous studies have linked higher inflammation in older adults to dementia, but this research is among the first to establish a connection between inflammation in early adulthood and reduced cognitive function in midlife.
“We know from long-term studies that brain changes leading to Alzheimer’s disease and other dementias may take decades to develop,” said Dr. Amber Bahorik, the study’s first author and a researcher at UCSF’s Department of Psychiatry and Behavioral Sciences and the Weill Institute for Neurosciences. “We wanted to see if health and lifestyle habits in early adulthood may play a part in cognitive skills in midlife, which in turn may influence the likelihood of dementia in later life.”
Published in Neurology on July 3, the study found that only 10% of participants with low inflammation performed poorly on tests of processing speed and memory, compared to 21% and 19% of those with moderate or high levels of inflammation, respectively. These disparities persisted even after adjusting for age, physical activity, and total cholesterol levels. Additionally, researchers found differences in executive functioning, which includes working memory, problem-solving, and impulse control.
The study tracked 2,364 adults participating in the CARDIA study, which aims to identify factors in young adulthood that contribute to cardiovascular disease two to three decades later. Participants, aged 18 to 30 at the study’s onset, were tested four times over 18 years for the inflammatory marker C-reactive protein (CRP). Cognitive tests were administered five years after the last CRP measurement, by which time most participants were in their forties and fifties.
The study’s demographics included approximately half female participants, with just under half being Black and the rest White. Among them, 45% had low stable inflammation, 16% had moderate or increasing inflammation, and 39% had high levels of inflammation.
Link Between Inflammation and Health Risks
Higher inflammation levels were also associated with physical inactivity, higher BMI, and smoking. “Inflammation plays a significant role in cognitive aging and may begin in early adulthood,” noted Dr. Kristine Yaffe, the study’s senior author and a professor of psychiatry, neurology, and epidemiology and biostatistics at UCSF. “There is likely a direct and indirect effect of inflammation on cognition.”
Dr. Yaffe is part of the pioneering team of experts who determined that 30% of dementia risk is preventable. Her recent research has explored the relationship between fragmented sleep in midlife and lower cognition, as well as the effects of personalized health and lifestyle changes in preventing memory loss in higher-risk older adults.
“Fortunately, there are ways to reduce inflammation — such as increasing physical activity and quitting smoking — that might be promising paths for prevention,” Yaffe added.
The study underscores the importance of maintaining a healthy lifestyle from a young age to safeguard cognitive function in later years.
