Blink rate in psychiatric illness.

Twenty-three patients diagnosed as depressed and a matched group of normal subjects were interviewed on three occasions using standardised procedures. Their behaviour was quantified from video recordings. The results indicate that blink rate is increased in depression and falls to normal levels during treatment. The effect on blink rate was found to be independent of medication, but was related to the degree of improvement in the patients' condition. By contrast a sample of schizophrenic patients seen on one occasion showed a reduced blink rate which was probably a result of neuroleptic administration.