Association of NAG levels with specific psychiatric symptoms in unipolar patients.

The levels of N-acetyl-beta-glucosaminidase (NAG) from 57 unipolar patients were compared to the scores of symptom severity for nine symptom clusters derived from the Symptom Check List (SCL-90). The depression and hostility clusters were significantly associated with NAG levels. In a separate study of 21 unipolar patients, six out of 31 mood symptoms were significantly associated with NAG levels, as were two out of seven tested RDC depression subtypes. Serotonin abnormalities may play a role in the production of many of these symptoms. A hypothesis that NAG could be a marker for serotonin activity is discussed.