User:Dmwhite98/Psychosis

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Psychosis is an abnormal condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior that is inappropriate for a given situation. There may also be sleep problems, social withdrawal, lack of motivation, and difficulties carrying out daily activities. Psychosis can have serious adverse outcomes.

As with many psychiatric phenomena, psychosis has several different causes. These include mental illness, such as schizophrenia or bipolar disorder, trauma, sleep deprivation, some medical conditions, certain medications, and drugs such as cannabis and methamphetamine. One type, known as postpartum psychosis, can occur after giving birth. The neurotransmitter dopamine is believed to play an important role. Acute psychosis is considered primary if it results from a psychiatric condition and secondary if it is caused by a medical condition or drugs. The diagnosis of a mental health condition requires excluding other potential causes. Testing may be done to check for central nervous system diseases, toxins, or other health problems as a cause.

Treatment may include antipsychotic medication, psychotherapy, and social support. Early treatment appears to improve outcomes. Medications appear to have a moderate effect. Outcomes depend on the underlying cause. In the United States about 3% of people develop psychosis at some point in their lives. The condition has been described since at least the 4th century BCE by Hippocrates and possibly as early as 1500 BCE in the Egyptian Ebers Papyrus.

Hallucinations[edit]
A hallucination is defined as sensory perception in the absence of external stimuli. Hallucinations are different from illusions and perceptual distortions, which are the misperception of external stimuli. Hallucinations may occur in any of the senses and take on almost any form. They may consist of simple sensations (such as lights, colors, sounds, tastes, or smells) or more detailed experiences (such as seeing and interacting with animals and people, hearing voices, and having complex tactile sensations). Hallucinations are generally characterized as being vivid and uncontrollable. Auditory hallucinations, particularly experiences of hearing voices, are the most common and often prominent feature of psychosis.

Up to 15% of the general population may experience auditory hallucinations (though not all are due to psychosis). The prevalence of auditory hallucinations in patients with schizophrenia is generally put around 70%, but may go as high as 98%. Reported prevalence in bipolar disorder ranges between 11% and 68%. During the early 20th century, auditory hallucinations were second to visual hallucinations in frequency, but they are now the most common manifestation of schizophrenia, although rates vary between cultures and regions. Auditory hallucinations are most commonly intelligible voices. When voices are present, the average number has been estimated at three. Content, like frequency, differs significantly, especially across cultures and demographics. People who experience auditory hallucinations can frequently identify the loudness, location of origin, and may settle on identities for voices. Western cultures are associated with auditory experiences concerning religious content, frequently related to sin. Hallucinations may command a person to do something potentially dangerous when combined with delusions.

Extracampine hallucinations are perceptions outside the normal sensory apparatus, such as the perception of sound through the knee. Visual extracampine hallucinations include seeing persons nearby that are not there.

Visual hallucinations occur in roughly a third of people with schizophrenia, although rates as high as 55% are reported. The prevalence in bipolar disorder is around 15%. Content commonly involves animate objects, although perceptual abnormalities such as changes in lighting, shading, streaks, or lines may be seen. Visual abnormalities may conflict with proprioceptive information, and visions may include experiences such as the ground tilting. Lilliputian hallucinations are less common in schizophrenia, and are more common in various types of encephalopathy such as peduncular hallucinosis.

A visceral hallucination, also called a cenesthetic hallucination, is characterized by visceral sensations in the absence of stimuli. Cenesthetic hallucinations may include sensations of burning, or re-arrangement of internal organs.

Delusions[edit]
Psychosis may involve delusional beliefs. A delusion is a fixed, false idiosyncratic belief, which does not change even when presented with incontrovertible evidence to the contrary. Delusions are context- and culture-dependent: a belief which inhibits critical functioning and is widely considered delusional in one population may be common (and even adaptive) in another, or in the same population at a later time. Since normative views may contradict available evidence, a belief need not contravene cultural standards in order to be considered delusional.

Prevalence in schizophrenia is generally considered at least 90%, and around 50% in bipolar disorder.

The DSM-5 characterizes certain delusions as "bizarre" if they are clearly implausible, or are incompatible with the surrounding cultural context. The concept of bizarre delusions has many criticisms, the most prominent being judging its presence is not highly reliable even among trained individuals.

A delusion may involve diverse thematic content. The most common type is a persecutory delusion, in which a person believes that an entity seeks to harm them. Others include delusions of reference (the belief that some element of one's experience represents a deliberate and specific act by or message from some other entity), delusions of grandeur (the belief that one possesses special power or influence beyond one's actual limits), thought broadcasting (the belief that one's thoughts are audible) and thought insertion (the belief that one's thoughts are not one's own).

The subject matter of delusions seems to reflect the current culture in a particular time and location. For example, in the US, during the early 1900s syphilis was a common topic, during the second world war Germany, during the cold war communists, and in recent years technology has been a focus. Some psychologists, such as those who practice the Open Dialogue method believe that the content of psychosis represents an underlying thought process that may, in part, be responsible for psychosis, though the accepted medical position is that psychosis is due to a brain disorder.

Historically, Karl Jaspers classified psychotic delusions into primary and secondary types. Primary delusions are defined as arising suddenly and not being comprehensible in terms of normal mental processes, whereas secondary delusions are typically understood as being influenced by the person's background or current situation (e.g., ethnicity; also religious, superstitious, or political beliefs).

Disorganization[edit]
Disorganization is split into disorganized speech (or thought), and grossly disorganized motor behavior. Disorganized speech or thought, also called formal thought disorder, is disorganization of thinking that is inferred from speech. Characteristics of disorganized speech include rapidly switching topics, called derailment or loose association; switching to topics that are unrelated, called tangential thinking; incomprehensible speech, called word salad or incoherence. Disorganized motor behavior includes repetitive, odd, or sometimes purposeless movement. Disorganized motor behavior rarely includes catatonia, and although it was a historically prominent symptom, it is rarely seen today. Whether this is due to historically used treatments or the lack thereof is unknown.

Catatonia describes a profoundly agitated state in which the experience of reality is generally considered impaired. There are two primary manifestations of catatonic behavior. The classic presentation is a person who does not move or interact with the world in any way while awake. This type of catatonia presents with waxy flexibility. Waxy flexibility is when someone physically moves part of a catatonic person's body and the person stays in the position even if it is bizarre and otherwise nonfunctional (such as moving a person's arm straight up in the air and the arm staying there).

The other type of catatonia is more of an outward presentation of the profoundly agitated state described above. It involves excessive and purposeless motor behaviour, as well as extreme mental preoccupation that prevents an intact experience of reality. An example is someone walking very fast in circles to the exclusion of anything else with a level of mental preoccupation (meaning not focused on anything relevant to the situation) that was not typical of the person prior to the symptom onset. In both types of catatonia there is generally no reaction to anything that happens outside of them. It is important to distinguish catatonic agitation from severe bipolar mania, although someone could have both.

Negative symptoms
Psychosis is associated with ventral striatal (VS) which is the part of the brain that is involved with the desire to naturally satisfy the bodies needs. When high reports of negative symptoms were recorded, there were significant irregularities in the left VS. While anhedonia, the inability to feel pleasure, is a commonly reported symptom in psychosis; anhedonia, the ability to feel pleasure, experiences are present in most people with schizophrenia. The impairment that may present itself as anhedonia derives from the inability to not only identify goals, but to also identify and engage in the behaviors necessary to achieve goals. Studies support a deficiency in the neural representation of goals and goal directed behavior by demonstrating that when the reward is not anticipated, there is a strong correlation of high reaction in the ventral striatum; reinforcement learning is intact when contingencies about stimulus-reward are implicit, but not when they require explicit neural processing; reward prediction errors '''are what the actual reward is versus what the reward was predicted to be.  In most cases positive prediction errors are considered an abnormal occurrence.''' A positive prediction error response occurs when there is an increased activation in a brain region, typically the striatum, in response to unexpected rewards. A negative prediction error response occurs when there is a decreased activation in a region when predicted rewards do not occur. Anterior Cingulate Cortex (ACC) response, taken as an indicator of effort allocation, does not increase with reward or reward probability increase, and is associated with negative symptoms; deficits in Dorsolateral Prefrontal Cortex (dlPFC) activity and failure to improve performance on cognitive tasks when offered monetary incentives are present; and dopamine mediated functions are abnormal.

Neurobiology
Psychosis has be often link to the overactivity of dopamine, a neurotransmitter that is responsible for how we feel pleasure. Dopamine is distributed throughout pathways known as mesolimbic pathway which is responsible for mediating pleasure and rewarding experiences. The two major sources of evidence given to support this theory are that dopamine receptor D2 blocking drugs (i.e., antipsychotics) tend to reduce the intensity of psychotic symptoms. Alongside that, there are drugs that increase the amount of dopamine released, or inhibit its reuptake (such as amphetamines and cocaine) can trigger psychosis in some people (see stimulant psychosis).

N-Methyl-D-aspartic acid (NMDA) receptor dysfunction has been proposed as a mechanism in psychosis. This theory is reinforced by the fact that certain drugs that cause hallucination and distort perception such as ketamine, PCP and dextromethorphan (at large overdoses) induce a psychotic state by blocking the NMDA receptors. The symptoms of dissociative intoxication are also considered to mirror the symptoms of schizophrenia, including negative symptoms. NMDA receptor antagonism, in addition to producing symptoms reminiscent of psychosis, mimics the neurophysiological aspects, such as reduction in the amplitude of P50, P300, and MMN evoked potentials. The Hierarchical Bayesian neurocomputational model is a statistical model that estimates the parameters of the likelihood of uncertain and/or random event after considering the needed evidence. This model is used alongside neuroimaging to show a correlation between the '''hypo-functioning of the NMDA receptors and delusion or hallucination symptoms resulting in the failure of the NMDA to effectively process perception from the most general state working its way toward a more specific state (top-down). With this being the case, the cancelation of the processing of sensory information as it is coming in (bottom-up) the maintain balance between the two forms of processing are thrown off'''. Excessive prediction errors in response to stimuli that would normally not produce such a response is thought to root from conferring excessive salience to otherwise mundane events. Dysfunction higher up in the hierarchy, where representation is more abstract, could result in delusions. The common finding of reduced GAD67 expression in psychotic disorders may explain enhanced AMPA mediated signaling, caused by reduced GABAergic inhibition.

The connection between dopamine and psychosis is generally believed to be complex. While dopamine receptor D2 suppresses adenylate cyclase activity, the D1 receptor increases it. If D2-blocking drugs are administered, the blocked dopamine spills over to the D1 receptors. The increased adenylate cyclase activity affects genetic expression in the nerve cell, which takes time. Hence antipsychotic drugs take a week or two to reduce the symptoms of psychosis. Moreover, newer and equally effective antipsychotic drugs actually block slightly less dopamine in the brain than older drugs whilst also blocking 5-HT2A receptors, suggesting the 'dopamine hypothesis' may be oversimplified. Soyka and colleagues found no evidence of dopaminergic dysfunction in people with alcohol-induced psychosis and Zoldan et al. reported moderately successful use of ondansetron, a 5-HT3 receptor antagonist, in the treatment of levodopa psychosis in Parkinson's disease patients.

A review found an association between a first-episode of psychosis and prediabetes.

Prolonged or high dose use of psychostimulants can alter normal functioning, making it similar to the manic phase of bipolar disorder. NMDA antagonists replicate some of the so-called "negative" symptoms like thought disorder in subanesthetic doses (doses insufficient to induce anesthesia), and catatonia in high doses). Psychostimulants, especially in one already prone to psychotic thinking, can cause some "positive" symptoms, such as delusional beliefs, particularly those persecutory in nature.

Peer Review
I '''did change hedonia to anhedonia. I had planned to do that from the start but I guess I forgot. Though when looking up hedonia it doesn't make you correct it and still gives the correct definition. As far as the making the part of anhedonia a definition, I kind of already did that in the parenthesis that says "the ability to feel pleasure", I don't think it necessary to add the other added function because it does have an effect on psychosis in this section. It is one of the main function that separate schizophrenia from psychosis, the rest are somewhat similar for both. I could be wrong and the added definition might be something that should be added, but I feel as though it swerves off topic.'''