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.