The pursuit of pleasure drives much of human behavior. It is why we love, eat, drink, play, and create. Without pleasure, there is no quality of life. People with anhedonia, however, have a decreased interest and sensitivity to rewarding experiences. Anhedonia is a common symptom of many psychiatric and neurological diseases, and it may be an early warning sign of dementia and schizophrenia.
A spectrum of symptoms
Anhedonia exists on a spectrum from mild to extreme. On the mild end, anhedonia may be a symptom found in people who do not have a psychological or neurological disorder. People who are very shy and introverted may have pleasure in social situations in small groups or one-on-one situations but have anhedonia in large groups or with strangers. People with social anxiety may also have similar anhedonia symptoms.
At the other end of the spectrum are people who have an inability to seek or feel pleasure at all. For these people, anhedonia can cut off the ability to lead a normal life. Typically, people with anhedonia are not diagnosed until it interferes with their functioning or is obvious to others. There are two types of anhedonia:
Social anhedonia is a lack of pleasure from social interaction. Physical anhedonia is lack of pleasure from physical exposures. People with social anhedonia have no interest in friendships or intimate relationships.
Physical anhedonia means people do not enjoy the taste of an ice cream cone or the touch of a loved one. They have no interest or pleasure from sex. This type of anhedonia does not usually have any relationship to the condition that causes it. Most people will have some of both types, although one type may be dominant.
Conditions that cause anhedonia
Anhedonia is a symptom of brain diseases that cause death of brain cells, like dementia. It can be a symptom of psychiatric disorders caused by lack of brain messengers, like serotonin in depression and dopamine in Parkinson’s disease. Finally, anhedonia can be a symptom of psychological conditions like post-traumatic stress disorder and substance abuse.
Anhedonia is common, and there are many pathways to get there. A recent study published in the American Medical Association’s journal JAMA Network Open reviewed 168 studies on anhedonia that included more than 16,000 people. Some people in the studies did not have a mental health disorder and some had either active major depression, major depression in remittance, schizophrenia, substance use disorder, Parkinson’s disease, or chronic pain. All the people in these studies were tested for anhedonia with a self-report questionnaire. The studies found that people with mental health disorders tested higher for anhedonia than people without a mental health disorder, including those who recovered from major depression. Of all the mental health conditions, major depression scored highest for anhedonia. Other studies have found more links:
Anhedonia is an early and primary symptom of frontotemporal dementia, a type of dementia that occurs in younger adults.
Anhedonia is one of two primary symptoms of major depression, along with sadness.
Social anhedonia in a young person may predict schizophrenia.
Older adults with anhedonia are five times more likely to develop Alzheimer’s disease.
Anhedonia might be linked to bipolar disorder and autism.
Anhedonia affects the frontostriatal brain region. In frontotemporal dementia, a loss of brain cells can be seen in this region on brain imaging studies. Brain imaging with functional MRI shows that anhedonia affects areas of the brain responsible for anticipation, reward, pleasure, decision making, and motivation. However, although imaging studies may show anhedonia, the gold standard for diagnosing anhedonia is self-reporting on standardized questionnaires like the Snaith-Hamilton Pleasure Scale (SHAPS; see table above) and a clinical interview with a mental health-care provider. SHAPS (uses 14 questions to rate a person’s ability to get pleasure from foods, interests, pastimes, social interaction, and pleasurable sensations.
The treatment of anhedonia depends on the cause. For example, anhedonia may improve with antidepressant medication for major depression, antipsychotic medication for schizophrenia, and medication that increases dopamine for Parkinson’s disease. But a person with depression and anhedonia may not respond as well to antidepressant medications. In some cases, the medications can make it worse as they interfere with libido and the ability to have an orgasm, and may cause blunted emotions. Researchers suggest that this may be caused by serotonin inhibiting the release of dopamine, which can interfere with reward, motivation, and pleasure circuitry.
Talk therapy (psychotherapy) is a treatment that helps many people with anhedonia. A common therapy, called behavioral activation, gives patients concrete tasks, such as going to parties or socializing, that they don’t find appealing. When the person completes the task and finds it somewhat pleasant, it creates a positive feedback cycle and increases the brain’s sensitivity to rewards.
Treatment with ketamine, an anesthesia medication, also shows promise. In one 2014 study in the Journal of Psychopharmacology, a single injection of ketamine reduced anhedonia within 40 minutes, and the improvement lasted for two weeks. A growing body of research suggests that this may be an effective treatment.