A new study suggests that isolation can result in reduced production of myelin - a protective nerve fiber - and could contribute to developing mental illness.
Myelin acts as an "insulating material" around the areas of nerve cells that send impulses to other nerve cells. Production of the fiber is controlled by nerve cells called oligodendrocytes, but is lost in diseases such as multiple sclerosis. Abnormal myelin has, in other studies, been linked to mental illnesses including autism, anxiety, schizophrenia, and depression.
The study, published in the journal Nature neuroscience, showed that mice who were deprived of social contact had reduced myelin production. Researchers stated this demonstrates that formation of oligodendrocytes is affected by environmental changes.
"We knew that a lack of social interaction early in life impacted myelination in young animals but were unsure if these changes would persist in adulthood," said Dr. Patrizia Casaccia, who led the study and is chief of the Center of Excellence for Myelin Repair at the Friedman Brain Institute at the Mount Sinai School of Medicine. "Social isolation of adult mice causes behavioral and structural changes in neurons, but this is the first study to show that it causes myelin dysfunction as well."
After observing the myelin drop in the mice, the researchers re-introduced them into a social group. Within four weeks, the social withdrawal symptoms were reversed.
"Our study demonstrates that oligodendrocytes generate new myelin as a way to respond to environmental stimuli, and that myelin production is significantly reduced in social isolation," said Casaccia. "Abnormalities occur in people with psychiatric conditions characterized by social withdrawal. Other disorders characterized by myelin loss, such as MS, often are associated with depression. Our research emphasizes the importance of maintaining a socially stimulating environment in these instances."