Study Reveals Inflammatory Proteins May Slow Cognitive Decline in Aging Adults

A new study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association found that elevated levels of 2 chemical mediators of inflammation, or cytokines, are connected with slower cognitive decline in aging adults.

“These are totally unexpected results,” said study co-senior author, Rudolph Tanzi, PhD, vice chair of Neurology and co-director of the Henry and Allison McCance Center for Brain Health at Massachusetts General Hospital (MGH), in a press release.

The study authors said that these findings could be used to help identify healthy people who are at risk for the condition before they have symptoms.

The new study’s objective was to discover whether measuring cytokines in the blood could help predict which healthy people will later experience cognitive decline, specifically in older people with normal cognition but who had undergone imaging tests and had deposits of amyloid beta in their brains, which are associated with Alzheimer disease (AD).

“We wanted to know why some people have amyloid in their brain and don’t seem to be affected, while other people experience cognitive decline,” said study co-senior author Jasmeer Chatwal, MD, PhD, a neurologist at MGH and a Harvard Aging Brain Study (HABS) co-investigator, in the press release.

The analysis included 298 men and women from HABS between 50 and 90 years of age who had normal cognitive abilities when they volunteered and underwent retesting annually. All participants had blood samples taken and went through positron emission tomography (PET) brain-imaging scans. PET scans were done to examine evidence of amyloid beta and other changes associated with AD, such as tau tangles.

Each participant’s blood was screened for 9 cytokines to see whether any were associated with the rate of cognitive decline and changes in the brain. The study found that people whose brains had a significant burden of amyloid beta, but also had high levels of the pro-inflammatory cytokine interleukin-12, experienced minor cognitive decline.

“However, men and women with elevated levels of amyloid declined more if they had a lower value of IL-12,” said lead study author Hyun-Sik Yang, MD, a neurologist at Brigham and Women’s Hospital and a HABS co-investigator, in the press release.

Fewer tau tangles were associated with high levels of IL-12, whereas elevated levels of interferon-gamma (IFN-γ) were connected with slower cognitive decline, whether or not a person had deposits of amyloid, according to the study authors.

The findings suggest that IL-12 and IFN-γ could be measured along with other biomarkers to predict future brain health in cognitively normal people, which does not exist in medicine. “We don’t have a ‘checkup from the neck up,’” Tanzi said in the press release.

REFERENCE

An unexpected discovery: Inflammatory proteins may slow cognitive decline in aging adults. Massachusetts General Hospital. Published June 23, 2021. Accessed June 23, 2021. https://www.massgeneral.org/news/press-release/An-unexpected-discovery-inflammatory-proteins-may-slow-cognitive-decline-in-aging-adults