Summary: A new study finds that higher inflammation in early adulthood is associated with reduced cognitive function in middle age. Researchers found that inflammation from factors like obesity and smoking can impact memory and processing speed.
This link, already observed in older adults, now extends to early adulthood, suggesting long-term effects on brain health. Reducing inflammation through lifestyle changes may help prevent cognitive decline.
Highlights:
- Impact of inflammation: Higher inflammation in young adults associated with poorer cognitive performance in middle age.
- Study data: Followed 2,364 adults over 18 years, measuring inflammation and cognitive abilities.
- Preventive measures: Physical activity and smoking cessation can reduce inflammation and potentially prevent cognitive decline.
Source: University of California, San Francisco
Greater inflammation in early adulthood is linked to poorer performance on skill 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, according to a new study from UC San Francisco.
Researchers have previously linked higher inflammation in older adults to dementia, but this is one of the first studies to link inflammation in early adulthood to poorer 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 Amber Bahorik, PhD, of the UCSF Department of Psychiatry and Behavioral Sciences and the Weill Institute for Neurosciences.
“We wanted to see if health and lifestyle habits in early adulthood might play a role in cognitive skills in middle age, which in turn might influence the likelihood of dementia later in life.”
In their study, the publication in Neurology On July 3, researchers found that only 10% of people with low inflammation performed 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, 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 as part of the CARDIA study, which aims to identify factors in young adulthood 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 an 18-year period for C-reactive protein (CRP), an inflammatory marker. They took the cognitive tests five years after their last CRP measurement, when most participants were in their 40s and 50s.
About half of the participants were women, just under half were black, and the rest were white. About 45% had stable, low inflammation, while 16% had moderate or increasing inflammation; 39% had higher levels.
A link between inflammation and health risks
Researchers have also linked higher inflammation levels to physical inactivity, higher BMI and current smoking.
“Inflammation plays an important role in cognitive aging and can begin in early adulthood,” said lead author Kristine Yaffe, MD, professor of psychiatry and behavioral sciences, neurology, and epidemiology and biostatistics at UCSF. “There is likely a direct and indirect effect of inflammation on cognition.”
Yaffe is part of the first team of experts to determine that 30% of dementia risk is preventable. His recent research has focused on the association between fragmented sleep and cognitive impairment in middle age and the effects of personalized health and lifestyle changes on preventing memory loss in high-risk older adults.
“Fortunately, there are ways to reduce inflammation – such as increasing physical activity and quitting smoking – that may be promising avenues for prevention,” Yaffe said.
Co-authors: Tina Hoang, MSPH, of the Northern California Research and Education Institute; David R. Jacobs, PhD, of the University of Minnesota; Deborah Levine, MD, PhD, of the University of Michigan, Ann Arbor.
Funding: Please see the document.
Disclosures: Yaffe reports serving on the data safety monitoring board for Eli Lilly and several studies sponsored by the National Institute on Aging, providing consulting services for Alpha Cognition, serving on the board of directors of Alector Inc., providing data, safety and monitoring services for the Dominantly Inherited Alzheimer’s Network Trials Unit, and serving on the scientific advisory board of Beeson and the Global Brain Health Council.
About this news on cognitive decline and inflammation research
Author: Suzanne Leigh
Source: University of California, San Francisco
Contact: Suzanne Leigh – UCSF
Picture: Image credited to Neuroscience News
Original research: Access closed.
“Association of Changes in C-Reactive Protein Level Trajectories in Early Adulthood with Cognitive Function in Midlife: The CARDIA Study” by Amber Bahorik et al. Neurology
Abstract
Association between changes in C-reactive protein level trajectories in early adulthood and cognitive function in midlife: the CARDIA study
Background and objectives
Inflammation in old age has been associated with dementia risk and preclinical cognitive decline, but less is known about inflammation in early adulthood and its potential influence on cognition in middle age. We sought to identify levels of inflammation in early adulthood and determine the association of these trajectories with cognition in middle age.
Methods
We used data from the Coronary Artery Risk Development in Young Adults study to identify trajectories of inflammation (C-reactive protein (CRP) levels < 10 mg/L) over 18 years to young adulthood (age range 24–58 years) in latent class analysis and to assess associations with cognition 5 years after the last CRP measurement (age range 47–63 years).
Six cognitive domains were assessed using tests of verbal memory, processing speed, executive function, verbal and categorical fluency, and global cognition; poor cognitive performance was defined as a decline ≥1 standard deviation below the mean on each domain. The primary outcome was poor cognitive performance. Logistic regression was used to adjust for demographics, smoking, alcohol consumption, physical activity, and APOE 4 status.
Results
Among the 2,364 participants, the mean (SD) age was 50.2 (3.5) years; 55% were female and 57% were white. Three CRP trajectories emerged over 18 years: stable lower (45%), moderate/increasing (16%), and persistently elevated (39%). Compared with stable lower CRP, persistently elevated CRP (adjusted odds ratio (AOR) 1.67, 95% CI 1.23–2.26) and moderate/increasing (AOR 2.04, 95% CI 1.40–2.96) had higher odds of poor processing speed; persistently elevated CRP additionally had higher odds of poor executive function (AOR 1.36, 95% CI 1.00–1.88).
For memory (aOR moderately/increasing 1.36, 95% CI 1.00–1.88; aOR consistently higher 1.18, 95% CI 0.90–1.54), letter fluency (aOR moderately/increasing 1.00, 95% CI 0.69–1.43; aOR consistently higher 1.05, 95% CI 0.80–1.39), category fluency (aOR moderately/increasing 1.16, 95% CI 0.82–1.63; aOR consistently higher 1.11, 95% CI 0.85–1.45), or global cognition (aOR moderately/increasing 1.16, 95% CI 0.82–1.63; aOR consistently higher 1.11, 95% CI 0.85–1.45), 0.85–1.45), no association was observed.
Discussion
Consistently elevated or moderate/increasing inflammation that begins in early adulthood may lead to impaired executive function and processing speed in middle age. Study limitations include selection bias due to loss to follow-up and reliance on CRP as the sole inflammatory marker. Inflammation is important for cognitive aging and may begin much earlier than previously thought.