Background
Anhedonia, the diminished capacity to experience pleasure, is a prominent symptom of major depressive disorder (MDD), schizophrenia and other neuropsychiatric disorders [
1‐
4]. Almost 30 years ago, Klein [
5] suggested that hedonic processing was not a unitary construct, but rather a complex of both anticipatory and consummatory components. Consummatory pleasure reflects the momentary pleasure that is experienced while engaged in an enjoyable activity, while anticipatory pleasure revolves around pleasure from future activities.
Anhedonia and depressed mood are the two core symptoms of MDD [
1]. Hasler and colleagues [
6] demonstrated that anhedonia together with increased stress reactivity was the most important candidate for psychopathological endophenotype of MDD. Joiner et al. [
7] found that MDD patients presented higher scores on Beck Depression Inventory (BDI) anhedonic items than schizophrenic subjects, suggesting that anhedonia was a specific state-like feature of depressive illness. However, Pelizza and Ferrari [
8] detected that anhedonia reached highly significant levels in 36.9 % of depressed patients and 45 % of schizophrenic patients according to the Physical Anhedonia Scale and the Social Anhedonia Scale, indicating that anhedonia could not be considered as a distinctive state in MDD.
Accumulating evidence suggested that depression was associated with anhedonia. Pizzagalli et al. [
9] found blunted reward responsiveness in patients with MDD, particularly when anhedonic symptoms were prominent. Treadway et al. [
10] observed an association between anhedonia and reduced motivation in an effort-based decision-making task in MDD. Liu et al. [
11] utilizing the Snaith–Hamilton Pleasure Scale (SHAPS) in Chinese populations indicated that patients with depression demonstrated more anhedonic symptoms than patients with schizophrenia and non-clinical individuals. Although the above studies suggested diminished hedonic capacity in MDD, they did not differentiate consummatory and anticipatory anhedonia. To date, only one study distinguished consummatory and anticipatory anhedonia, stating low anticipatory pleasure but intact consummatory pleasure in depressed individuals [
12].
In schizophrenia, anhedonia has long been considered a cardinal symptom [
13] and a component of negative symptoms [
14,
15]. Studies on anhedonia in schizophrenia have provided inconsistent results. Schizophrenia patients reported more severe anhedonia than healthy controls on self-report measures and semistructured interviews [
16‐
18], but had normal levels of pleasant emotions while in response to pleasurable stimuli [
19,
20]. Distinction of deficits in anticipatory and consummatory pleasure may help to understand the mixed findings on anhedonia in schizophrenia. A new self-report questionnaire, the Temporal Experience of Pleasure Scale (TEPS), developed by Gard et al. [
21], was used to assess consummatory and anticipatory pleasure. Several studies showed anticipatory, but not consummatory anhedonia in schizophrenia [
22‐
24]. However, the study of Strauss et al. [
25] had the opposite result. Buck and Lysaker [
26] suggested that anticipatory pleasure predicted concurrent and prospective levels of positive symptoms, emotional discomfort and interpersonal function, whereas consummatory pleasure predicted only concurrent positive symptoms.
In summary, little attention has been paid to detect the consummatory and anticipatory pleasure impairment in MDD, and there were inconsistent results on consummatory and anticipatory pleasure in schizophrenia. Moreover, there has been no study to compare the difference between MDD and schizophrenia on consummatory and anticipatory pleasure.
In this study, we assessed consummatory and anticipatory pleasure using TEPS in MDD and schizophrenia. The present study has two main aims: (1) examining the discrimination of consummatory and anticipatory pleasure between MDD or schizophrenia and healthy controls; and (2) exploring the relationships between different anhedonia types and clinical variables, including severity, duration of illness and admission times in MDD and schizophrenia.
Discussion
The present study indicated that both consummatory and anticipatory pleasure were impaired in MDD. The results were not completely consistent with most previous studies which usually reflected either consummatory anhedonia [
7,
8,
11] or anticipatory pleasure impaired by depression [
12]. It is noteworthy that several theorists have proposed that anhedonic features are related to altered dopaminergic circuitry in MDD [
32‐
34]. Particularly, the dysfunction of dopaminergic mesolimbic and mesocortical reward circuits has been singled out as the major neurobiological correlate of anhedonia [
35,
36]. Mesolimbic dopaminergic neurons projecting into the frontal cortex and nucleus accumbens have been suggested to be involved in the therapeutic actions of some antidepressants [
37,
38], through 5-HT modulation of DA function [
39]. Previous studies have shown that antidepressants can influence anhedonia in patients with MDD in dopaminergic mesolimbic reward circuits likely caused by the increase in serotonin neurotransmission [
38,
40,
41]. We speculate that the difference between the present study and other studies may be due to the influence of antidepressants on anhedonia.
This study also found anticipatory and consummatory pleasure impaired in schizophrenia. Gard et al. [
22] and Chan et al. [
24] observed lower anticipatory pleasure in schizophrenia compared with healthy controls. But Strauss et al. [
25] found lower score on consummatory pleasure. Our findings were not completely consistent with the mentioned studies. Strauss et al. [
25] supposed that the main difference between their study and the study of Gard et al. and Chan et al. was in the percentage of patients who were prescribed typical antipsychotics. We agreed with this speculation. In the present study, 21 % of patients were prescribed typical antipsychotics, compared to 31 % in Gard et al. 29 % in Chan et al. and 12 % in Strauss et al. Previous evidence showed that typical antipsychotics could produce anhedonia via dopamine antagonism [
42], and a neurobiological study showed that dopamine was strongly linked to anticipatory rather than consummatory pleasure [
43,
44]. In contrast, consummatory pleasure was more strongly linked to the serotonin and opioid systems [
45,
46]. Further evidence also revealed that typical antipsychotics lead to more reward prediction dysfunction [
47], and therefore anticipatory rather than consummatory pleasure was even more easily influenced by typical antipsychotics. Another reason for this might be that previous studies missed some factors such as relapse times, acute or chronic phase and patients in hospitals or community homes [
22,
24,
25].
In the correlation study, we found diminished consummatory and anticipatory pleasure associated with depression severity in patients with MDD. The results were in concordance with other studies showing that the severity of anhedonia was positively correlated with the severity of depressive symptoms in MDD [
48‐
52]. We also found that TEPS-CON and TEPS-ANT had significant positive correlations with the duration of illness and admission times in MDD. The results indicated that impaired consummatory and anticipatory pleasure resulted in worse prognosis of MDD. It was consistent with the opinion that anhedonia was a post-depressive “scar” symptom in MDD [
53].
In previous studies, anhedonia did not show strong association with the duration of illness, number of admissions, cumulative time in hospital and length of current admission in schizophrenia. It remains fairly stable over time and is generally considered to reflect as a “trait” rather than a “state” in schizophrenia [
15,
54,
55]. However, whether anticipatory and consummatory anhedonia would be stable over time in schizophrenia was unclear. The current results indicated that TEPS-ANT and TEPS-CON scores had no significant relationship with the course of illness and admission times, which suggested that both anticipatory and consummatory anhedonia remained relatively stable in schizophrenia.
Herbener and Harrow found significant correlations between anhedonia and negative symptoms, but no meaningful relationships with positive symptoms in schizophrenia in a 10-year longitudinal study [
56]. However, other studies indicated significant associations between anhedonia and positive symptoms [
57,
58]. No statistically significant associations between anhedonia and positive, negative and general psychopathology scores as measured by PANSS were detected in the research of Huxley et al. [
59]. In this study, we found that TEPS-CON significantly correlated with PANSS total scores, negative and positive symptoms, but TEPS-ANT had no meaningful relationship with any symptoms. The results suggested that consummatory anhedonia might vary with the severity of negative and positive symptoms, but anticipatory anhedonia seemed to be independent of many clinical variables, such as positive and negative symptoms. This seemingly showed that anticipatory anhedonia was more stable than consummatory pleasure deficit in patients with schizophrenia.
There were some limitations in this study. First, the sample of patients was recruited from clinical randomly as long as the patients met the inclusion criteria. All the patients in our study were taking medication; although the differences among medications were taken into account, we did not consider the influence of different doses on anhedonia in patients with MDD and schizophrenia. Second, different sites and inter-rater bias could influence the measurement results. Finally, this study did not measure TEPS in different clinical phases to understand whether consummatory and anticipatory pleasure would vary with time.
Conclusions
Consummatory and anticipatory anhedonia were both found in MDD and schizophrenia. The two anhedonia components were significantly associated with depression severity, duration of illness and admission times in MDD. Therefore, we speculated that both consummatory and anticipatory pleasure deficit could be regarded as a “state” in MDD. However in schizophrenia, consummatory anhedonia was only associated with negative and positive symptoms, and anticipatory anhedonia had no significant correlation with any clinical characteristics. So, anticipatory and consummatory anhedonia can be considered as a “trait”, and it seemed more stable than consummatory anhedonia in schizophrenia.
Authors’ contributions
YY conceived the study and the design, translated TEPS into Chinese and helped to draft and revise the manuscript. YLi participated in its design, conducted the statistical analyses and wrote the manuscript. WJ participated in its design, the data acquisition and the scale translation. ZY, XS, ZJ, ZD, YLiu, SM and JZ coordinated the study and data acquisition. All authors read and approved the final manuscript.