Higher inflammation in early adulthood is associated with poorer performance on skills tests in middle age.
Young adults who have higher levels of inflammation, associated with obesity, physical inactivity, chronic disease, stress and smoking, may experience reduced cognitive function in middle age, a new study from the University of California, San Francisco, has found.
Researchers have previously linked higher inflammation in older adults to dementia, but this is one of the first studies to connect inflammation in early adulthood to lower cognitive abilities in middle age.
“We know from long-term studies that the brain changes that lead to Alzheimer’s disease and other dementias can take decades to develop,” said first author Dr. Amber Bahorik, of 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 can influence cognitive abilities in midlife, which in turn can influence the likelihood of dementia later in life.”
In his study, the publication in Neurology On July 3, researchers found that only 10% of those with low inflammation performed poorly on tests of processing speed and memory, compared with 21% and 19%, respectively, of those with moderate or high levels of inflammation.
When the researchers adjusted for factors such as age, physical activity and total cholesterol, the disparities remained in processing speed; and the researchers also found differences in executive functioning, which includes working memory, problem solving and impulse control.
The study followed 2,364 adults in the CARDIA study, which aims to identify factors in early adulthood that lead to cardiovascular disease two to three decades later.
Participants were aged 18 to 30 years when they entered the study and were tested four times for the inflammatory marker C-reactive protein (CRP) over an 18-year period. They took the cognitive tests five years after their last CRP measurement, by which time most participants were in their forties and fifties.
About half of the participants were women, just under half were black, and the rest were white. About 45% had lower, stable inflammation, while 16% had moderate or increasing inflammation and 39% had higher levels.
A link between inflammation and health risks
Researchers also linked higher levels of inflammation with physical inactivity, higher BMI and current smoking.
“Inflammation plays a major role in cognitive aging and may begin in early adulthood,” said senior author Dr. Kristine Yaffe, professor of psychiatry and behavioral sciences, neurology, epidemiology and biostatistics at UCSF. “Inflammation likely has both a direct and indirect effect on cognition.”
Yaffe is a member of the first team of experts to determine that 30% of dementia risk is preventable. His recent research has examined the association between sleep deprivation and lower cognitive ability in midlife, and the effects of personalized health and lifestyle changes in preventing memory loss in older adults at higher risk.
“Fortunately, there are ways to reduce inflammation (such as increasing physical activity and quitting smoking) that could be promising avenues for prevention,” Yaffe said.