Schizophrenia is one of the most widely misunderstood of human maladies. The truth of the illness is far different from popular caricatures of a sufferer muttering incoherently or lashing out violently.
People with schizophrenia are, in fact, not more likely to be violent than people without schizophrenia. About one per cent of the worldwide population has schizophrenia, affecting men and women, rich and poor, and people of all races and cultures. It can be treated with medication and psychosocial treatments, though the treatments don’t work well for every person and for every symptom. Most of all, it impacts everything that makes us human: the way one thinks, the way one behaves, and the way one feels – particularly the ability to experience pleasure.
Three-quarters of people with schizophrenia suffer from anhedonia: the decreased pleasure from events or activities that were once enjoyed. Friends will no longer be fun to be around, and once-tasty meals can come to taste bland. (It is also a core symptom of depression.) From a clinical perspective, anhedonia is assessed via an interview with a mental-health professional in which a person is asked about pleasure and enjoyment in various life activities such as socialising, eating, working or participating in hobbies.
In my research, I have incorporated methods, theories and measures from the field of affective science to better understand anhedonia in schizophrenia. Affective science theory and research is grounded in the notion that emotions, such as pleasure, are more fully captured and understood through comprehensive, multimethod assessment. I assess emotional responses by measuring changes in facial expression, reports of experience, brain activity and body responses when people with and without schizophrenia are engaging with emotionally salient stimuli such as films, pictures, foods or simply talking about their own lives.
Can people with schizophrenia accurately and reliably report on their feelings, given that they often have profound thinking disturbances? Yes. People with schizophrenia can use the same broad dimensions when describing their feelings as people without schizophrenia: valence, or how pleasant or unpleasant a particular emotion is; and arousal, or how highly activating or calming an emotion is. Excitement represents a high-activation pleasant emotion; serenity represents a low-activation positive emotion, and boredom reflects a low-activation unpleasant emotion. People with schizophrenia report experiencing similar (or slightly lower) amounts of pleasant emotion, compared with those without schizophrenia, in the presence of emotionally evocative stimuli and in daily life, regardless of changes in medication status.
However, pleasure is not just about experiencing an enjoyable moment. It also involves anticipation – a connection between one’s present and future selves. This is a crucial distinction. Pleasure is not just about the consummatory (that is, in-the-moment) experience, but also anticipatory pleasure: the ability to both look forward to future pleasurable experiences, as well as to enjoy the anticipation of pleasure in and of itself. Schizophrenia makes this distinction clear. People with this illness are less likely to predict or anticipate that future events will be pleasurable, as well as less likely to experience pleasure in anticipation of things to come. This, in turn, makes it less likely that they will seek out pleasurable experiences at all.
Anticipating whether something in the future will be pleasurable requires myriad cognitive skills, including imagination, reflection, drawing upon past experiences, and maintaining an image or emotional state. Consider the example of deciding where to go on holiday. You might think about visiting a national park in the United States, which leads you to call forth a past vacation you took to visit Yellowstone National Park. This then prompts you to predict that your vacation will be relaxing and enjoyable, taking in the sights and the wildlife. With this prediction you actually begin to experience pleasure now – in the knowledge that you will be experiencing pleasure soon. This is anticipatory pleasure. These processes will support your motivational system such that you will make your travel reservations (approach motivation and behaviour) and, once you take your holiday, you will experience consummatory pleasure. You will savour (maintain) the pleasure from the holiday, and this experience will be remembered. And the next time you need to make a holiday choice, this memory might be called upon to restart the temporal process again.
One way that I have assessed the experience of pleasure-in-anticipation in my research is by using a self-report measure of physical/sensory anticipation experience called the Temporal Experience of Pleasure Scale. This measure includes items that assess both anticipatory and consummatory pleasure experience for different physical sensations (for example, ‘When I think about eating my favourite food, I can almost taste how good it is’). People with schizophrenia score lower on the anticipatory pleasure scale compared with people without schizophrenia, but they score the same on the consummatory pleasure scale. This pattern has been found among those who are at risk for developing schizophrenia, are early in the course of the illness or have had the illness for many years, and in people with schizophrenia from different countries and cultures.
Other research approaches to studying anhedonia in schizophrenia draw heavily from neuroscience research, in part because the quest for pharmacological treatments is informed by what we know about the human brain. In particular, the neuroscience of motivation, which includes several processes and brain networks, has been used to understand anhedonia in schizophrenia. Motivation processes include a calculation of how much effort is needed to achieve a desired, pleasant outcome (reward), a plan of how to obtain that outcome, and a behavioural response to get the reward. This neuroscience approach has illuminated a number of key findings about anhedonia in schizophrenia, showing for example that people with schizophrenia have difficulties in computing the value and effort needed to obtain pleasant outcomes and exerting effort to achieve rewards.
It is essential to also measure phenomenological experience: if you want to know how someone is feeling, you need to ask them. No measure of brain activity, facial expression or bodily response is a substitute for assessing feelings. My colleagues and I have shown that people with schizophrenia can report clearly on how they feel, and assuming that people with schizophrenia cannot do so is not only incorrect, but can also perpetuate myths and misperceptions about the illness (the loopy, incoherent muttering and flailing anger). Current neuroscience research on human brain networks that support thinking, feeling and perceiving other people has demonstrated that many of the brain’s same networks participate in the support of these psychologically diverse processes and functions, rendering the search for psychological process-specific networks nearly obsolete.
Anhedonia, or diminished pleasure, in schizophrenia is most apparent when it comes to anticipating future events. People with schizophrenia report expecting less pleasure from enjoyable activities, and experience less pleasure when anticipating future events, than people without schizophrenia. However, when actually doing these pleasant activities, people with and without schizophrenia report experiencing the same amount of pleasure. The example of anhedonia in schizophrenia illustrates that pleasure is not a single process. Instead, pleasure emerges from a host of interacting cognitive, affective and motivational systems, dysfunction in any one of which can lead to problems with pleasure.