Psychometric evaluation of the Temporal Experience of Pleasure Scale (TEPS) in a German sample.

Anhedonia, or the inability to experience pleasure, is commonly observed in schizophrenia. It has been suggested that patients with schizophrenia are unable to predict future pleasurable events, but show intact experience of in-the-moment pleasure. Therefore, the Temporal Experience of Pleasure Scale (TEPS), a self-report measure allowing the assessment of anticipatory and consummatory pleasure, has been developed. To validate the German version of the TEPS, we recruited 59 healthy control participants and 51 patients with schizophrenia or schizoaffective disorder who completed the TEPS as well as a battery of psychometric tests to assess psychopathology, in particular self-rated anhedonia and clinician-rated apathy as well as overall measures of negative symptoms. We found acceptable to good internal consistency and a factor structure comparable to the original version. Scores of the TEPS were related to measures of anhedonia and apathy, but not with other measures of psychopathology. The present results suggest that the German version of the TEPS shows adequate reliability and validity to assess the construct of anhedonia. However, differential aspects of anticipatory and consummatory pleasure should be further investigated in clinical samples.

Reward System Dysfunction as a Neural Substrate of Symptom Expression Across the General Population and Patients With Schizophrenia.

Dysfunctional patterns of activation in brain reward networks have been suggested as a core element in the pathophysiology of schizophrenia. However, it remains unclear whether this dysfunction is specific to schizophrenia or can be continuously observed across persons with different levels of nonclinical and clinical symptom expression. Therefore, we sought to investigate whether the pattern of reward system dysfunction is consistent with a dimensional or categorical model of psychosis-like symptom expression. 23 patients with schizophrenia and 37 healthy control participants with varying levels of psychosis-like symptoms, separated into 3 groups of low, medium, and high symptom expression underwent event-related functional magnetic resonance imaging while performing a Cued Reinforcement Reaction Time task. We observed lower activation in the ventral striatum during the expectation of high vs no reward to be associated with higher symptom expression across all participants. No significant difference between patients with schizophrenia and healthy participants with high symptom expression was found. However, connectivity between the ventral striatum and the medial orbitofrontal cortex was specifically reduced in patients with schizophrenia. Dysfunctional local activation of the ventral striatum depends less on diagnostic category than on the degree of symptom expression, therefore showing a pattern consistent with a psychosis continuum. In contrast, aberrant connectivity in the reward system is specific to patients with schizophrenia, thereby supporting a categorical view. Thus, the results of the present study provide evidence for both continuous and discontinuous neural substrates of symptom expression across patients with schizophrenia and the general population.