Antibodies: The body's own antidepressants

Up to 20 percent of the population have antibodies against this receptor in their blood.

Usually, the blood-brain barrier prevents these antibodies crossing from the blood into the brain.

If the antibodies bind to NMDA receptors in the brain, these are then removed from the nerve cell membrane ('internalized').

The effect of these NMDA receptor autoantibodies can typically influence the symptoms of the underlying encephalitis, contributing to epileptic seizures, impaired movement, psychosis and loss of cognitive function.

Autoantibody levels increase with age

In a new study, Hannelore Ehrenreich and her colleagues from the Max Planck Institute of Experimental Medicine in Göttingen have discovered that the concentration of these autoantibodies in the blood of mice and humans can fluctuate considerably over time.

According to the researchers, chronically stressed mice show a higher level of NMDA receptor autoantibodies in their blood compared to their non-stressed conspecifics.

Ehrenreich and her team also analysed the concentration of antibodies in the blood of young migrants.

Mice with a more permeable blood-brain barrier and NMDA receptor autoantibodies in the brain were significantly more mobile and less depressed during times of chronic stress than their conspecifics with an intact blood-brain barrier.