Previous studies have linked higher inflammation levels in late-life to increased dementia risk and preclinical cognitive decline. Less is known however about how inflammation in early adulthood affects cognition in midlife. In the present study, researchers investigated the effects of health and lifestyle habits linked to high inflammation during early adulthood on midlife cognition.
For the study, they examined data from 2,364 adults who were followed from early adulthood for 18 years. During this time, particpants were tested four times for the inflammatory marker C-reactive protein (CRP). They also underwent cognitive tests five years after their last CRP measurement while in their 40’s and 50’s.
Altogether, around 45% of participants had lower stable inflammation, 16% had moderate or increasing inflammation and 39% had higher levels. Higher levels of inflammation were linked to physical inactivity, higher BMI and current smoking.
Ultimately, the researchers found that 10% of those with low inflammation performed poorly in tests of processing speed and executive function- including working memory, problem-solving, and impulse control, whereas the same was true for 21% and 19% of those with moderate or higher levels of inflammation.
Study limitations included selection bias due to loss of follow-up and reliance on CRP as the only inflammatory marker.
"Inflammation plays a significant role in cognitive aging and may begin in early adulthood. There is likely a direct and indirect effect of inflammation on cognition," said senior author Kristine Yaffe, MD, a professor of psychiatry and behavioral sciences, neurology, and epidemiology and biostatistics at the University of California San Francisco.
"Fortunately, there are ways to reduce inflammation- such as by increasing physical activity and quitting smoking- that might be promising paths for prevention," added Yaffe.
Sources: Science Daily, Neurology