Polygraphic evaluation of laughing and smiling in schizophrenic and depressive patients

Polygraphic recordings was used to assess laughing and smiling, and results were compared for 34 normal controls, 24 schizophrenic patients, and 15 depressive patients. The schizophrenic and the depressive patients showed reduced 'laughs of pleasure,' i.e., laughing in reaction to a comic video assessed by laughing score; however, the depressive patients in remission showed the same laughing reaction as the controls. 'Smiles as social signals' during interviews were reduced for the schizophrenic patients but remained for the depressive patients. There was a tendency for greater reduction of both laughing and smiling in disorganized- versus paranoid-type schizophrenia, suggesting that the disturbance of affect might be more severe in the former. These results show the possibility that polygraphic recording of laughing and smiling might be a useful method for investigating the disturbance of affect in schizophrenic and depressive patients.