The Emotion Paradox of Anhedonia in Schizophrenia: Or Is It?

Abstract

Anhedonia has long been considered a core clinical feature of schizophrenia.1–3 The most common definition of anhedonia is that it reflects a diminished capacity to experience pleasure. Although this definition clearly applies to many individuals diagnosed with major depression,4–7 recent empirical evidence suggests that it may not adequately describe the affective abnormalities characteristic of schizophrenia.8 For example, individuals with schizophrenia report levels of current (ie, in the moment) positive emotion and arousal that are comparable to healthy controls when exposed to stimuli in the laboratory (for meta-analyses, see Cohen and Minor, 2010; Llerena et al 2012),9,10 show similar increases in positive emotion when engaged in activities in their daily lives,11,12 and display comparable neural activation to controls when reporting their current positive emotions in response to pleasant stimuli (see Taylor et al13 for a meta-analysis). Such evidence has led some to conclude that anhedonia should no longer be viewed as a diminished capacity for pleasure in this patient population.8,9,14,15 However, it is clear that not all aspects of emotional experience are normal in schizophrenia. For example, compared with healthy controls, patients typically report reductions in pleasure when queried during clinical interviews that obtain retrospective (ie, past) or prospective (ie, future) reports of pleasure,16–18 as well as questionnaires that use trait (eg, Positive and Negative Affect Scale19 or hypothetical (eg, Chapman Anhedonia Scales)20 self-report formats. Experience sampling studies also indicate that schizophrenia patients have a reduced frequency of pleasurable experiences compared with controls,11,12,21,22 suggesting a diminution in pleasure-seeking behavior. At first glance, findings indicating normal in-the-moment experience of positive emotion appear to be at odds with those indicating diminished pleasure across all types of noncurrent positive emotion reports obtained via retrospective, prospective, trait, and hypothetical self-report formats. Some have even termed this apparent discrepancy the “emotion paradox” in schizophrenia to reflect a violation of the commonsense notion that reports of emotional experience obtained across different self-report formats should converge. But is this the case? Should one expect self-reports of current and noncurrent (eg, prospective, retrospective) positive emotion to be similar? A large body of research on healthy individuals indicates that reports of current and noncurrent positive emotion typically show low correlations23,24 and that healthy individuals expect more pleasure in the future and remember more pleasure in the past compared with what they actually experience in the moment.25 Overestimation of past and future relative to current positive emotions, as well as low correlations between these types of self-reports, is thought to occur because self-reports of current and noncurrent emotion require access to different sources of emotion knowledge.26 In the field of affective science, the sources of emotion knowledge that are accessed when making prospective, retrospective, and current reports of positive emotion are well-delineated. In their seminal article on the “Accessibility Model of Emotional Self-Report,” Robinson and Clore26 review this literature and discuss how reports of current feelings require access to experiential emotion knowledge, whereas reports of noncurrent feelings (eg, retrospective, prospective, trait, and hypothetical) require access to semantic emotion knowledge. Semantic emotion knowledge includes beliefs about which types of emotions are likely to be elicited by specific situations (eg, “Social interactions are enjoyable”), as well as general beliefs that a person holds about himself or herself (“I am generally a happy person”). When viewed in relation to the accessibility model, overestimation of past and future relative to current positive emotion occurs because healthy individuals access semantic knowledge stores when making these noncurrent emotion reports, and thus rely on beliefs about how they generally feel or how specific situations make them feel. In healthy individuals, overestimation of noncurrent positive emotion therefore at least in part reflects that most healthy individuals believe that they are generally in a moderately positive mood and that specific types of situations (eg, vacations) are pleasurable.26