However, a large body of evidence suggests that hedonic responses are intact in schizophrenia, and that what is reported to be anhedonia is a reflection of dysfunction in other processes related to reward. Overall, a failure of reward prediction is thought to lead to impairment in the generation of cognition and behavior required to obtain rewards, despite normal hedonic responses.Another theory links abnormal brain lateralization to the development of being left-handed which is significantly more common in those with schizophrenia. This abnormal development of hemispheric asymmetry is noted in schizophrenia. Studies have concluded that the link is a true and verifiable effect that may reflect a genetic link between lateralization and schizophrenia.Bayesian models of brain functioning have been utilized to link abnormalities in cellular functioning to symptoms. Both hallucinations and delusions have been suggested to reflect improper encoding of prior expectations, thereby causing expectation to excessively influence sensory perception and the formation of beliefs. In approved models of circuits that mediate predictive coding, reduced NMDA receptor activation, could in theory result in the positive symptoms of delusions and hallucinations. Diagnosis
Criteria
Schizophrenia is diagnosed based on criteria in either the Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association or the International Statistical Classification of Diseases and Related Health Problems (ICD) published by the World Health Organization (WHO). These criteria use the self-reported experiences of the person and reported abnormalities in behavior, followed by a psychiatric assessment. The mental status examination is an important part of the assessment.
Medical anesthetics
Several medical anesthetics are used as recreational drugs, including diethyl ether (a drug that is no longer used medically, due to its high flammability and the development of safer alternatives) and nitrous oxide, which is widely used in the 2010s by dentists as an anti-anxiety drug during dental procedures. Diethyl ether has a long history of use as a recreational drug. The effects of ether intoxication are similar to those of alcohol intoxication, but more potent. Also, due to NMDA antagonism, the user may experience all the psychedelic effects present in classical dissociatives such as ketamine in forms of thought loops and the feeling of the mind being disconnected from ones body. Nitrous oxide is a dental anesthetic that is used as a recreational drug, either by users who have access to medical-grade gas canisters (e.g., dental hygienists or dentists) or by using the gas contained in whipped cream aerosol containers. Nitrous oxide inhalation can cause pain relief, depersonalisation, derealisation, dizziness, euphoria, and some sound distortion. Classification by effect
It is also possible to classify inhalants by the effect they have on the body. Some solvents act as depressants, causing users to feel relaxed or drowsy while others act as stimulants. Many inhalants act primarily as asphyxiant gases, with their primary effect due to oxygen deprivation. Nitrous oxide can be categorized as a dissociative drug, as it can cause visual and auditory hallucinations. Other agents may have more direct effects at receptors, as inhalants exhibit a variety of mechanisms of action.