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Chronic Inflammation Linked to Memory Loss

A major new study ties inflammation at midlife to later cognitive decline and Alzheimer's

spinner image Mature woman takes cognitive test at doctor's office.
A patient takes a cognitive test for Alzheimer’s disease.
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People who harbor high levels of chronic inflammation at midlife are more likely to experience memory loss and problems with thinking in subsequent decades, according to a new study in the journal Neurology — the first long-term look at the link between inflammatory blood markers and brain health.

To reach their conclusion, which points to why things such as diet and exercise might be important to Alzheimer's prevention, researchers used data from the Atherosclerosis Risk in Communities (ARIC) study at Johns Hopkins University, tracking more than 12,000 people with an average age of 57 for about two decades. They found that adults with the highest levels of inflammation markers in their 40s, 50s and early 60s had a steeper rate of cognitive decline in their later years.

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“Higher levels of inflammation were most strongly associated with declines in memory,” says Keenan A. Walker, a postdoctoral fellow in neurology at Johns Hopkins’ School of Medicine and the study’s lead author. “It implicated inflammation in memory disorders, namely Alzheimer's disease.”  

At the beginning of the study, researchers measured levels of several markers of inflammation in blood samples, assigning each volunteer an inflammation score. Participants were also tested for levels of C-reactive protein, another key indicator of inflammation in the body. To measure brain health, participants took standard tests for memory and other brain functions at the study’s onset, again about six to nine years later, and again at the end of the study.

Compared with participants with the lowest levels of inflammation markers, those with the highest levels experienced an 8 percent steeper decline in thinking and memory skills over the course of the study, researchers reported. The group with the highest C-reactive protein levels had a 12 percent steeper decline in these skills than the group with the lowest levels.

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Although inflammation is a normal process designed to protect the body from injury, disease and infection in the short term, inflammation that persists can be harmful. Chronic inflammation is associated with autoimmune diseases, as well as common conditions like heart disease and diabetes.

It’s not clear whether inflammation actually triggers brain deficits in old age, however. “It’s still possible that inflammation may simply be a result of underlying dementia rather than a cause,” Walker says. “But by looking at inflammation during middle adulthood, we can more confidently infer that inflammation comes first. It’s unlikely that you have neurodegenerative changes at age 40 or 50.” 

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The research dovetails with a previous analysis from the ARIC study, which found that people with high levels of inflammation during middle age have smaller brain volumes, particularly in regions involved in memory, such as the hippocampus.

Taking steps to quell inflammation in middle age could have a significant payoff down the line. “The things you do in your 40s and 50s will likely have an effect on how healthy your brain is in your 60s and 70s,” Walker says.

His advice: Eat a healthy diet, get regular exercise, maintain a healthy weight, and take measures to prevent or treat existing cardiovascular disease or diabetes. Says Walker, “It’s never too early to start thinking about preserving brain health.”