Higher levels of inflammation, our immune system's response to varied injuries and infections, in older adults have previously proved to be associated with an increased risk of dementia and cognitive decline. However, the specific link between inflammation in early adulthood and cognition in midlife is not yet clear. In a new study published in Neurology Journal, a team of researchers led by Dr Amber L. Bahorik from the University of California, San Francisco (US) investigated the association between inflammation in early adulthood and lower cognitive abilities in midlife.
This research followed 2,364 participants (mean age 50.2 years, 55% female and 57% white) of the CARDIA (Coronary Artery Risk Development in Young Adults) study, which investigated factors in young adulthood that may be tied to cardiovascular disease decades later in people initially healthy and aged between 18 and 30 years at enrolment. The participants of this study were tested four times (in years 7, 15, 20, and 25) over a period of 18 years for the C-reactive protein (CRP), an inflammatory marker. Five years after the last CRP measurement, cognition was assessed through a battery of tests evaluating verbal memory, processing speed, executive function, fluency, and global cognition.
Researchers identified three CRP trajectories, corresponding to lower, moderate, or high CRP (i.e. inflammation) levels which remained mostly stable or increased over the 18 year-period this marker was measured. Compared to participants with lower stable levels of CRP, those with higher and moderate/increasing levels had higher probabilities of poor cognitive performance, specifically observed for processing speed and executive function. Although this study shows some limitations, such as the use of CRP as the only inflammatory marker, it seems that there may be an effect of inflammation on cognitive ageing starting in early adulthood. More research is needed to confirm this link and to develop possible strategies to delay cognitive impairment through the inflammatory processes early in life.