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A new sign of aging has been identified in the brain which researchers say could help in better treating cognitive disorders.

According to Zee News, researchers at Weizmann Institute in Israel have found that cognitive impairment is associated with aging of the immune system and not only with chronological age, as earlier believed. The findings have also show that earlier held notions about the blood-brain barrier may have to be revised.

Researchers found that blood-brain barrier actually provides for a unique interface between brain and immune compounds in blood. The interface called Choroid Plexus, acts as a mediator. Researchers found that the immune system helps in preserving cognitive abilities and promotes growth of new brains cells, contrary to earlier held belief that immune compounds could not cross the barrier. Researchers also found that the brain releases certain danger signals which are sensed through the interface. In turn, the immune system responds to restore normal activity. Weakening of the immune system is thus seen as an indication of aging.

"The choroid plexus acts as a 'remote control' for the immune system to affect brain activity. Biochemical 'danger' signals released from the brain are sensed through this interface; in turn, blood-borne immune cells assist by communicating with the choroid plexus. This cross-talk is important for preserving cognitive abilities and promoting the generation of new brain cells," said Michal Schwartz of the neurobiology department at institute said in a release.

To test their hypothesis, researchers mapped gene expression changes in 11 organs in young and old mice as part of a comparative study. In the Choroid Plexus of older mice researchers found interferon beta, a protein released by body to combat viral infections. Researchers also found interferon beta in aging human brains. When they injected an antibody to prevent release of interferon beta, the loss of cognitive ability in mice was reversed, leading researchers to conclude that immunological health plays a key role in maintaining cognitive ability.