This could mean that it is only later that this inflammatory response ends up going haywire and contributing to the problem, they said.
It is known that there is a dysregulation of the immune system, and in particular an increase in inflammation, in Alzheimer’s disease, commented Professor Charles Ramassamy of the National Institute for Scientific Research. However, we don’t know how and when this happens.
Researchers at the Massachusetts General Hospital wanted to know whether blood levels of certain proteins involved in inflammation (cytokines) could predict which healthy seniors are most at risk for cognitive decline. They were particularly interested in those in whom brain imaging showed the presence of beta-amyloid plaques in the brain.
The role of cytokines …
By studying some 300 subjects between the ages of 50 and 90, they found that those with high levels of beta-amyloid plaques, but also high blood levels of a pro-inflammatory cytokine called interleukin-12 (IL-12 ), were less likely to suffer from cognitive decline.
In contrast, those with high levels of beta-amyloid plaques but low blood levels of IL-12 later experienced greater cognitive decline.
Elevated levels of another pro-inflammatory cytokine, gamma interferon (IFN-γ), have also been associated with less pronounced cognitive decline, regardless of whether the subject has beta-amyloid deposits or not.
This is a surprise, because patients who have high levels of these cytokines were expected to have faster cognitive decline, said Professor Ramassamy. It goes against what was known until now.
… and that of IFN-y
Some researchers believe that beta-amyloid forms in the brain to defend it from infection, but eventually causes irreversible damage. Elevated levels of IL-12 and IFN-γ could show that the patient’s immune system is strong, and that it is able to suppress infections before they reach the brain and cause the formation of plates.
The increase in these two proteins could perhaps protect against certain pathogens, it would decrease the access of these pathogens to the brain, which then could increase the inflammation, said Mr. Ramassamy. It’s an interesting hypothesis.
Consideration could now be given to developing tests to measure blood levels of IL-12 and IFN-γ to predict the brain health of people who do not currently have cognitive problems.
Consideration could also be given to offering IL-12 and IFN-γ supplements to people with beta-amyloid deposits who have lower levels of beta-amyloid, but a lot of work will be needed before. that it is possible, warned Mr. Ramassamy.
The findings of this study were published by the medical journal Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.