anhedonia anhedonia 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 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. anhedoniapronunciation/ˌænhiˈdoʊniə/ an-hee-doh-nee-ə specialtypsychiatry definition while anhedonia was originally defined in 1896 by théodule-armand ribot as the reduced ability to experience pleasure, it has been used to refer to deficits in multiple facets of reward. re-conceptualizations of anhedonia highlight the independence of "wanting" and "liking". "wanting" is a component of anticipatory positive affect, mediating both the motivation (i.e. incentive salience) to engage with reward, as well as the positive emotions associated with anticipating a reward. "liking", on the other hand, is associated with the pleasure derived from consuming a reward. the consciousness of reward-related processes has also been used to categorize reward in the context of anhedonia, as studies comparing implicit behavior versus explicit self-reports demonstrate a dissociation of the two. 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. anhedonia has also been used to refer to "affective blunting", "restricted range of affect", "emotional numbing", and "flat affect", particularly in the context of post-traumatic stress disorders. in ptsd patients, scales measuring these symptoms correlate strongly with scales that measure more traditional aspects of anhedonia, supporting this association. causes studies in clinical populations, healthy populations, and animal models have implicated a number of neurobiological substrates in anhedonia. regions implicated in anhedonia include the prefrontal cortex as a whole, particularly the orbitofrontal cortex (ofc), the striatum, amygdala, anterior cingulate cortex (acc), hypothalamus, and ventral tegmental area (vta). neuroimaging studies in humans have reported that deficits in consummatory aspects of reward are associated with abnormalities in the ventral striatum and medial prefrontal cortex, while deficits in anticipatory aspects of reward are related to abnormalities in hippocampal, dorsal acc and prefrontal regions. these abnormalities are generally consistent with animal models, except for inconsistent findings with regard to the ofc. this inconsistency may be related to the difficulty in imaging the ofc due to its anatomical location, or the small number of studies performed on anhedonia; 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). occurrence major depressive disorder anhedonia occurs in roughly 70% of people with a major depressive disorder. anhedonia is a core symptom of major depressive disorder; therefore, individuals experiencing this symptom can be diagnosed with depression, even in the absence of low/depressed mood. 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. schizophrenia anhedonia is one of the negative symptoms of schizophrenia. although five domains are usually used to classify negative symptoms, factor analysis of questionnaires yield two factors, with one including deficits in pleasure and motivation. people with schizophrenia retrospectively report experiencing fewer positive emotions than healthy individuals. however, "liking" or consummatory pleasure, is intact in people with schizophrenia, as they report experiencing the same degree of positive affect when presented with rewarding stimuli. neuroimaging studies support this behavioral observation, as most studies report intact responses in the reward system (i.e. ventral striatum, vta) to simple rewards. however, studies on monetary rewards sometimes report reduced responsiveness. more consistent reductions are observed with regard to emotional response during reward anticipation, which is reflected in a reduced responsiveness of both cortical and subcortical components of the reward system. 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. substance-related disorders anhedonia is common in people who are dependent upon any one or more of a wide variety of drugs, including alcohol, opioids, and nicotine. although anhedonia becomes less severe over time, it is a significant predictor of relapse. post-traumatic stress disorder 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. parkinson's disease anhedonia occurs frequently in parkinson's disease, with rates between 7%–45% being reported. whether or not anhedonia is related to the high rates of depression in parkinson's disease is unknown. bipolar depression anhedonia is also reported to appear in people with bipolar depression. attention deficit hyperactivity disorder 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. sexual anhedonia main article: sexual anhedonia sexual anhedonia in males is also known as 'ejaculatory anhedonia'. this condition means that the man will ejaculate with no accompanying sense of pleasure. the condition is most frequently found in males, but females can experience lack of pleasure when the body goes through the orgasm process as well. sexual anhedonia may be caused by: hyperprolactinaemia hypoactive sexual desire disorder (hsdd), also called inhibited sexual desire low levels of the hormone testosterone spinal cord injury multiple sclerosis use of ssri antidepressants or having used ssri antidepressants in the past. use (or previous use) of antidopaminergic neuroleptics (anti-psychotics) fatigue physical illness it is very uncommon that a neurological examination and blood tests can determine the cause of a specific case of sexual anhedonia. patients may be prescribed sustained-release bupropion to aid in treatment, which has been shown to relieve sexual dysfunction even in patients without depression. social anhedonia