Increased inflammation in early adulthood may predict worsening cognition in midlife

Key takeaways:

• Researchers examined cognitive shifts in 2,364 individuals enrolled in the CARDIA study.
• Those with a moderate trajectory were more than twice as likely to have poor performance in processing speed.

Persistent higher or moderate-to-increasing inflammation that begins in early adulthood may result in worsening midlife executive function and processing speed, according to data published in Neurology.

“Over the life course, inflammation levels tend to have substantial intra-individual variability and this variation in levels of inflammation over time may be a critical predictor for cognitive aging,” Kristine Yaffe, MD, a professor of psychiatry, neurology and epidemiology and director of the Center for Population Brain Health at the University of California, San Francisco, and colleagues wrote.

Yaffe and colleagues sought to identify inflammation levels through early adulthood and determine their associations with midlife cognition trajectories, by reviewing data from the prospective cohort CARDIA study, which enrolled more than 5,000 initially healthy individuals aged 18 to 30 years between 1985 and 1986.

Their analysis included identify inflammation trajectories (C-reactive protein [CRP] level <10 mg/L) in 2,364 participants (mean age, 50.2 years; 55% female; 57% white) who were subsequently assessed for associations with cognition 5 years after the last CRP measurement was taken when participants were aged 47 to 63 years. Participants completed a baseline visit and had a series of follow-up visits at years 2, 5, 7, 10, 15, 20, 25 and 30.

At year 30, 5 years after the last CRP measurement, participants were given a battery of tests from which six cognitive domains were evaluated: verbal memory, processing speed, executive function, verbal and category fluency, global cognition; poor cognitive performance was defined as a decline of 1 standard deviation less than the mean on each domain. The primary outcome was poor cognitive performance.

Yaffe and colleagues employed logistic regression to adjust for demographics, smoking, alcohol use, physical activity and APOE 4 status. From this analysis, three CRP trajectories were created: lower stable (45%), moderate/increasing (16%) and consistently higher (39%).

According to results, each of the three cognitive trajectories remained either stable or increased from the early stage of adulthood into midlife. 

Researchers observed that those with both consistently higher (adjusted OR = 1.67; 95% CI, 1.23–2.26) and moderately/increasing (aOR = 2.04; 95% CI, 1.4–2.96) CRP had higher odds of poor processing speed compared with those deemed “lower stable,” while individuals with consistently higher CRP recorded higher odds of poor executive function (aOR = 1.36; 95% CI, 1–1.88).

Further, data showed no associations between CRP trajectories for either memory, letter or category fluency, or global cognition. 

“Although current prevention efforts mainly focus on late life, our study provides evidence for the need to also target brain health in middle age,” Yaffe and colleagues noted. “More research is needed to improve early detection of those at highest risk of poor cognitive performance and to determine effective strategies to delay the process of cognitive aging by addressing the drivers of inflammation.”

Reference:

Can inflammation in early adulthood affect memory, thinking in middle age? https://www.aan.com/PressRoom/Home/PressRelease/5183. Published July 3, 2024. Accessed July 11, 2024.

Editor's Note: This story was updated on July 17, 2024 to further clarify and adjust wording in the results section.