Immune System Affects Cognitive Decline

By Sondra Forsyth

Scientists have discovered that cognitive decline over the years may be connected to a weakening immune system.

The study, by researchers from the Weizmann Institute, Rehovot, Israel, breaks new ground in the understanding of a connection between the brain and the immune system.

Until recently, scientists believed that the barrier between blood and brain prevents blood-borne immune cells from destroying brain tissue. But the Weizmann researchers have shown the contrary – that there is an interaction between blood and brain. This originates in the choroid plexus, which is found in each of the brain’s four ventricles.

Prof. Michal Schwartz of the institute’s Neurobiology Department said that the “cross talk” between the brain and the immune system is “important for preserving cognitive abilities and promoting the generation of new brain cells.”

That finding led Schwartz and her group to suggest that cognitive decline over the years may be connected not only to one’s “chronological age” but also to one’s “immunological age.”

In the study, the researchers used both young and aged mice to map changes in 11 organs, including the choroid plexus. That enabled them to identify a “signature of aging” that exists only in the choroid plexus. One of the signature’s main elements is interferon beta – a protein that usually fights viral infection.

If interferon beta is blocked, the scientists found, cognitive abilities can be restored. Thus, treatments aimed at blocking interferon beta may help reverse cognitive decline.

The scientists reached the same conclusion in an analysis of human brains.

The study was published in the journal Science.