Understanding anhedonia in schizophrenia through lexical analysis of natural speech

Anhedonia is a negative prognostic indicator in schizophrenia. However, the underlying nature of this emotional deficit is unclear. Laboratory studies examining patients’ emotional reactions under controlled circumstances have failed to find evidence for a diminished hedonic response, instead finding that patients’ reactions to laboratory stimuli are characterised by high levels of negative emotion. The present study employed lexical analysis of natural speech in 52 patients and 49 non-patient controls while they discussed separate neutral, pleasant and unpleasant autobiographical memories. Patients with clinically rated anhedonia, versus other patients and controls, showed a dramatic increase in negative emotion expression when discussing pleasurable memories, but they showed no corresponding decrease in positive emotion. These findings provide further evidence that “anhedonia” is more reflective of negative emotional states than the absence of positive ones. These findings also raise questions about how positive and negative emotions can be simultaneously co-activated in patients with schizophrenia.