Greater inflammation in early adulthood, in the late 20s, is linked to lower performance on tests of cognitive ability in middle age, in the late 40s. Specifically, young adults with higher levels of inflammation, which is linked to obesity, physical inactivity, chronic disease, stress, and smoking, may experience decreased cognitive function in middle age, according to a new study from the University of California, San Francisco (USA) published in Neurology.
Researchers have previously linked greater inflammation in older adults to dementia, but this is one of the first studies to link inflammation in early adulthood to cognitive decline 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,” says first author Amber Bahorek of the Department of Psychiatry and Behavioral Sciences at the University of California, San Francisco and the Weill Neuroscience Institute in the United States.
“We wanted to see if healthy habits and lifestyle in early adulthood could play a role in cognitive abilities in midlife, which in turn could influence the likelihood of developing dementia later in life.” In their study, the researchers found that only 10% of people with low inflammation scored poorly on tests of processing speed and memory, compared with 21% and 19%, respectively, of people with moderate or high levels of inflammation.
When the researchers adjusted for factors such as age, physical activity and total cholesterol, the differences in processing speed remained; 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 study.
CARDIA, which aims to identify factors in youth that lead to cardiovascular disease two to three decades later. Participants were between 18 and 30 years old when they entered the study, and were tested four times over 18 years for C-reactive protein (CRP). They had cognitive tests five years after their last CRP measurement, at which time most participants were in their 40s and 50s.
Nearly half of the participants were women. Just under half were black and the rest were white. About 45% had less stable inflammation, while 16% had moderate or increasing inflammation. Thirty-nine% had higher levels. The researchers also linked higher levels of inflammation to physical inactivity, higher body mass index and current smoking.
“Inflammation plays an important role in cognitive aging and can begin in early adulthood,” says lead author Christine Yaffe, professor of psychiatry and behavioral sciences, neuroscience, epidemiology, and biostatistics at UCLA.
“There is likely to be a direct and indirect effect of inflammation on cognition.” Yaffe is part of the first expert group to identify that 30% of the risk of dementia is preventable. His recent research has looked at the association between fragmented sleep and cognitive decline in midlife and the effects of personal 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, which could be promising avenues for prevention,” Yaffe concludes.
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