Қызығушылық пен қуаныш сезімінің жоқтығы

Inability to feel pleasure

Anhedonia is a diverse array of deficits in hedonic function, including reduced motivation or ability to experience pleasure. While earlier definitions emphasized the inability to experience pleasure, anhedonia is currently used by researchers to refer to reduced motivation, reduced anticipatory pleasure (wanting), reduced consummatory pleasure (liking), and deficits in reinforcement learning. In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM 5), anhedonia is a component of depressive disorders, substance related disorders, psychotic disorders, and personality disorders, where it is defined by either a reduced ability to experience pleasure, or a diminished interest in engaging in previously pleasurable activities. While the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD 10) does not explicitly mention anhedonia, the depressive symptom analogous to anhedonia as described in the DSM 5 is a loss of interest or pleasure. Learning has also been proposed as an independent facet of reward that may be impaired in conditions associated with anhedonia, but empirical evidence dissociating learning from either "liking" or "wanting" is lacking. a number of studies have reported reduced activity in the OFC in schizophrenia and major depression, as well as a direct relationship between reduced activity and anhedonia. Researchers theorize that anhedonia may result from the breakdown in the brain's reward system, involving the neurotransmitter dopamine. Anhedonia can be characterised as "impaired ability to pursue, experience and/or learn about pleasure, which is often, but not always accessible to conscious awareness". The conditions of akinetic mutism and negative symptoms are closely related. In akinetic mutism, a stroke or other lesion to the anterior cingulate cortex causes reduction in movement (akinetic) and speech (mutism).

Anhedonia occurs in roughly 70% of people with a major depressive disorder. The Diagnostic and Statistical Manual of Mental Disorders (DSM) describes a "lack of interest or pleasure", but these can be difficult to discern given that people tend to become less interested in things which do not give them pleasure. The DSM criterion of weight loss is probably related, and many individuals with this symptom describe a lack of enjoyment of food. They can portray any of the non psychotic symptoms and signs of depression.

Anhedonia is one of the negative symptoms of schizophrenia. Schizophrenia is associated with reduced positive prediction errors (a normal pattern of response to an unexpected reward), which a few studies have demonstrated to be correlated with negative symptoms. People with schizophrenia demonstrate impairment in reinforcement learnings tasks only when the task requires explicit learning, or is sufficiently complex. Implicit reinforcement learning, on the other hand, is relatively intact. These deficits may be related to dysfunction in the ACC, OFC and dlPFC leading to abnormal representation of reward and goals.

Anhedonia is common in people who are dependent upon any one or more of a wide variety of drugs, including alcohol, opioids, cannabinoids, and nicotine. Although anhedonia becomes less severe over time, it is a significant predictor of relapse.

While PTSD is associated with reduced motivation, part of the anticipatory "wanting", it is also associated with elevated sensation seeking, and no deficits in physiological arousal, or self reported pleasure to positive stimuli. PTSD is also associated with blunted affect, which may be due to the high comorbidity with depression.

Anhedonia is also reported to appear in people with bipolar depression.

Anhedonia may be associated with ADHD. Impairments of dopaminergic and serotonergic function in the brain of those with ADHD result in dysregulation of reward processing which can lead to anhedonia.

Social anhedonia is defined as a disinterest in social contact and a lack of pleasure in social situations, and is characterized by social withdrawal. This characteristic typically manifests as an indifference to other people. In contrast to introversion, a nonpathological dimension of human personality, social anhedonia represents a deficit in the ability to experience pleasure. Additionally, social anhedonia differs from social anxiety in that social anhedonia is predominantly typified by diminished positive affect, while social anxiety is distinguished by both decreased positive affect and exaggerated negative affect. This trait is currently seen as a central characteristic, as well as a predictor, of schizophrenia spectrum disorders. It is also widely linked to autism spectrum disorder.

The term anhedonia is derived from the Greek an , "without" and hēdonē, "pleasure". Interest in the nature of pleasure and its absence dates back to ancient Greek philosophers such as Epicurus. The concept was formally coined by Théodule Armand Ribot and later used by psychiatrists Paul Eugen Bleuler and Emil Kraepelin to describe a core symptom of schizophrenia. Loren and Jean Chapman further distinguished between two types of anhedonia: physical anhedonia, or a deficit in the ability to experience physical pleasure, and social, or a deficit in the ability to experience interpersonal pleasure. Recent research suggests that social anhedonia may represent a prodrome of psychotic disorders. First degree relatives of individuals with schizophrenia show elevated levels of social anhedonia, higher baseline scores of social anhedonia are associated with later development of schizophrenia. These findings provide support for the conjecture that it represents a genetic risk marker for schizophrenia spectrum disorders. Additionally, elevated levels of social anhedonia in patients with schizophrenia have been linked to poorer social functioning. Socially anhedonic individuals perform worse on a number of neuropsychological tests than non anhedonic participants, and show similar physiological abnormalities seen in patients with schizophrenia. as well as autism spectrum disorder. Blanchard and colleagues (2011) found individuals with social anhedonia also had elevated rates of lifetime mood disorders including depression and dysthymia compared to controls.

As mentioned above, social anxiety and social anhedonia differ in important ways. It has yet to be determined what the exact relationship between social anhedonia and social anxiety is, and if one potentiates the other. Individuals with social anhedonia may display increased stress reactivity, meaning that they feel more overwhelmed or helpless in response to a stressful event compared to control subjects who experience the same type of stressor. This dysfunctional stress reactivity may correlate with hedonic capacity, providing a potential explanation for the increased anxiety symptoms experienced in people with social anhedonia. In an attempt to separate out social anhedonia from social anxiety, the Revised Social Anhedonia Scale didn't include items that potentially targeted social anxiety. Social anhedonia is a dimension of both negative and positive schizotypy. It involves social and interpersonal deficits, but is also associated with cognitive slippage and disorganized speech, both of which fall into the category of positive schizotypy. Not all people with schizophrenia display social anhedonia and likewise, people who have social anhedonia may never be diagnosed with a schizophrenia spectrum disorder if they do not have the positive and cognitive symptoms that are most frequently associated with most schizophrenia spectrum disorders. Social anhedonia may be a valid predictor of future schizophrenia spectrum disorders; This sex difference is stable throughout time (from adolescence into adulthood) and is also seen in people with schizophrenia spectrum disorders. These results may reflect a more broad pattern of interpersonal and social deficits seen in schizophrenia spectrum disorders. On average, males with schizophrenia are diagnosed at a younger age, have more severe symptoms, worse treatment prognosis, and a decrease in overall quality of life compared to females with the disorder. These results, coupled with the sex difference seen in social anhedonia, outline the necessity for research on genetic and hormonal characteristics that differ between males and females, and that may increase risk or resilience for mental illnesses such as schizophrenia.

L. J. and J. P. Chapman were the first to discuss the possibility that social anhedonia may stem from a genetic vulnerability. More recently, DISC1 has been associated with social anhedonia within the general population. Tomppo identified a specific DISC1 allele that is associated with an increase in characteristics of social anhedonia. They also identified a DISC1 allele associated with decreased characteristics of social anhedonia, that was found to be preferentially expressed in women. More research needs to be conducted, but social anhedonia may be an important intermediate phenotype (endophenotype) between genes associated with risk for schizophrenia and phenotype of the disorder.

Researchers studying the neurobiology of social anhedonia posit that this trait may be linked to dysfunction of reward related systems in the brain. This circuitry is critical for the sensation of pleasure, the computation of reward benefits and costs, determination of the effort required to obtain a pleasant stimulus, deciding to obtain that stimulus, and increasing motivation to obtain the stimulus. In particular, the ventral striatum and areas of the prefrontal cortex (PFC), including the orbitofrontal cortex (OFC) and dorsolateral (dl) PFC, are critically involved in the experience of pleasure and the hedonic perception of rewards. With regards to neurotransmitter systems, opioid, gamma Aminobutyric acid and endocannabinoid systems in the nucleus accumbens, ventral pallidum, and OFC mediate the hedonic perception of rewards.

Recent studies have found people who do not have any issue processing musical tones or beat, yet receive no pleasure from listening to music. Specific musical anhedonia is distinct from melophobia, the fear of music.