Early-Life Inflammation Causes Middle-Age Cognitive Decline

Higher levels of inflammation during early adulthood, specifically in one's twenties and thirties, may be associated with cognitive decline and memory issues in middle age, according to a study published in the July 3, 2024, online edition of Neurology®, the medical journal of the American Academy of Neurology. The research focused on levels of C-reactive protein (CRP) in the bloodstream, a marker indicating inflammation produced by the liver. However, the study does not establish a causal relationship between elevated CRP levels and dementia; it solely demonstrates a correlation ().

Link Between Early Adulthood Inflammation and Cognitive Decline

Inflammation is categorized into acute and chronic types. Acute inflammation occurs as part of the body's immune response to combat infections or injuries, typically short-term and localized. In contrast, chronic inflammation is persistent and considered unhealthy, characterized by low-grade inflammation lasting for months or even years throughout the body. This type of inflammation can result from conditions such as autoimmune disorders (e.g., rheumatoid arthritis, multiple sclerosis), physical stress, or other factors. Symptoms may include joint pain, digestive issues, and fatigue.

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Ways to reduce chronic inflammation

It includes getting regular exercise, following an anti-inflammatory heart healthy diet and getting enough sleep.

“Late-life inflammation has been linked to dementia risk and the earliest signs of cognitive decline, but less is known about inflammation in young adults and if this could influence cognition in midlife,” said study author Kristine Yaffe, MD, of University of California, San Francisco. “Our study found that having consistently higher or moderate inflammation starting in early adulthood may negatively affect a person’s ability to plan, focus and manage multiple tasks as well as how quickly they can process information in middle age.”

The study involved 2,364 people age 24 to 58. They were followed for 18 years.

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Participants’ inflammation levels were measured at the start of the study and three more times throughout the study.

Researchers divided participants into three groups based on inflammation levels: consistently higher, moderate or increasing and lower stable. Of the total participants, 911 people, or 39%, had consistently higher inflammation; 381 people, or 16%, had moderate or increasing inflammation; and 1,072, or 45%, had lower stable inflammation.

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Five years after their last inflammation measurement, participants were given six tests to examine thinking and memory skills.

On a test that measures processing speed and memory, participants were given a key showing numbers and corresponding symbols. They then drew those symbols on a separate list of random numbers as quickly as possible. Of those in the low group, 10% had poor cognitive performance, while those in the middle group and high group had 21% and 19%, respectively.

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After adjusting for factors such as age, physical activity and total cholesterol, researchers found that both the high and moderate groups were more likely to have poor performance in processing speed and executive function.

For processing speed, researchers found that those in the moderate group were more than two times more likely to have poor performance and those in the highest group were nearly two times more likely to have poor performance than those in the lowest group. For executive function, those with the highest CRP levels had a 36% higher risk of poor performance.

“Inflammation is important for cognitive aging and may begin much earlier than previously known,” said Yaffe. “Although current prevention efforts mainly focus on late life, our study provides evidence for the need to also target brain health in middle age. 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.”

A limitation of the study was that other conditions associated with elevated levels of inflammation, such as stroke, high blood pressure and diabetes, were not assessed.

Reference:

Systemic inflammation during midlife and cognitive change over 20 years - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511107/)

Source-Medindia