In recent years, the candidate symptom approach in schizophrenia has led to a growing interest in social anhedonia. Social anhedonia is defined as a reduced capacity to experience pleasure in social situations, and multiple studies have reported elevated levels in people with schizophrenia.1–3
Social anhedonia among people with schizophrenia is a stable condition across time and clinical status and is relatively independent of symptoms such as depression and psychosis.1
Moreover, elevated social anhedonia in healthy individuals has been associated with an increased vulnerability to the development of schizophrenia.4–6
Further, it has been proposed that anhedonia is an enduring trait in which the severity varies based on a wide range of individual differences.7
It was recently hypothesized that the severity of anhedonia measured by self-report questionnaires among patients with schizophrenia may be moderated by episodic memory deficits.8
Indeed, self-report anhedonia questionnaires, such as the Chapman scales,9
require patients to reflect on hedonic memories to estimate the intensity of their emotional experiences. Recalling the subjective experience of pleasure associated with past hedonic experiences could be quite difficult for some patients in light of the episodic memory deficits that characterize schizophrenia.10,11
Thus, the congruence between the measurement of anhedonia through self-report questionnaires and the genuine reduction of the hedonic capacity could be compromised by these memory deficits. This possible relation between anhedonia and episodic memory has been examined in patients with schizophrenia8,12
and in healthy individuals.13
Burbridge and Barch12
examined whether performance of a standard nonemotional episodic memory task moderated the relation between anhedonia questionnaire ratings and the ratings of affective eliciting stimuli. Their results showed that better memory performance was not associated with a stronger relation between anhedonia ratings and subjective emotional experience of positive stimuli. In the experimental protocol by Horan and colleagues,8
patients had to first rate their emotional responses to pleasant foods and film clips and then complete a surprise memory recall task about their emotions after a 4-hour delay. Results showed no significant difference between patients and controls in the delayed recall of the pleasant emotions. They concluded that self-reported anhedonia is not secondary to deficiencies in encoding and short-term retention for pleasurable experiences. However, as acknowledged by the authors, their memory task might not have been sensitive enough to variations in anhedonia, as performance was quite high owing to the small number of evocative stimuli and to the use of a short delay between encoding and recalling the hedonic experiences. Finally, in 2006, Mathews and Barch13
showed that higher levels of physical and social anhedonia in healthy individuals did not influence the memory performance for emotional words.
Although recent findings suggest that self-reported anhedonia among patients with schizophrenia is not influenced by episodic memory deficits, there is still a need for a more precise investigation of potential links between anhedonia and emotional memory. First, it is uncertain whether the severity of a specific type of anhedonia modulates the memory performance for a congruent type of emotional stimuli. This suggests that self-reported social anhedonia among patients with schizophrenia may be moderated by memory performance for social emotional information only. Second, it is still unclear whether social anhedonia is directly associated with the failure of positive emotional valence to enhance memory among patients with schizophrenia.14
Finally, it may be important to examine whether or not self-reported social anhedonia is linked to specific memory biases. Psychiatric symptoms can bias cognitive and affective information processing by altering the way such information is processed, organized and represented. Brébion and colleagues15
examined the relation between memory biases and both positive and negative symptoms in 40 patients with schizophrenia. They found that hallucination scores correlated with an increased bias toward false recognition of nonpresented words (familiarity bias), whereas anhedonia was significantly correlated with a more conservative bias, that is, with fewer false recognitions of nonpresented words (novelty bias). As a whole, emotional memory biases and deficits associated with social anhedonia still need to be better understood.
The primary goal of our study was to determine whether or not social anhedonia measured in people with schizophrenia and in healthy individuals would be associated with variations in emotional memory performance and/or biases during an emotional face recognition memory task. We hypothesized that the severity of social anhedonia among patients with schizophrenia would be significantly and negatively correlated with the recognition memory accuracy for happy faces and with the magnitude of the enhancement of recognition memory accuracy by positively valenced information. We also expected that elevated social anhedonia among patients with schizophrenia would be associated with a novelty detection bias for happy faces.