Instruct: Given a question, retrieve relevant documents that can help answer the question.
Query: Are hallucinations common on schizophrenia?
A mild form of hallucination is known as a disturbance, and can occur in most of the senses above. These may be things like seeing movement in peripheral vision, or hearing faint noises or voices. Auditory hallucinations are very common in schizophrenia. They may be benevolent (telling the subject good things about themselves) or malicious, cursing the subject, etc. Auditory hallucinations of the malicious type are frequently heard, for example people talking about the subject behind their back. Like auditory hallucinations, the source of the visual counterpart can also be behind the subject's back. Their visual counterpart is the feeling of being looked or stared at, usually with malicious intent. Frequently, auditory hallucinations and their visual counterpart are experienced by the subject together.
The relationship between religion and schizophrenia is of particular interest to psychiatrists because of the similarities between religious experiences and psychotic episodes; religious experiences often involve auditory and/or visual hallucinations, and those with schizophrenia commonly report similar hallucinations, along with a variety of beliefs that are commonly recognized by modern medical practitioners as delusional. In general, religion has been found to have "both a protective and a risk increasing effect" for schizophrenia.
Hallucinations can occur in any of the five senses, although auditory and visual hallucinations are encountered more frequently than tactile (touch), olfactory (smell) or gustatory (taste) hallucinations.
Auditory hallucinations are typical of psychoses: third-person hallucinations (i.e. voices talking about the patient) and hearing one's thoughts spoken aloud ("gedankenlautwerden" or "écho de la pensée") are among the Schneiderian first rank symptoms indicative of schizophrenia, whereas second-person hallucinations (voices talking to the patient) threatening or insulting or telling them to commit suicide, may be a feature of psychotic depression or schizophrenia. Visual hallucinations are generally suggestive of organic conditions such as epilepsy, drug intoxication or drug withdrawal. Many of the visual effects of hallucinogenic drugs are more correctly described as visual illusions or visual pseudohallucinations, as they are distortions of sensory experiences, and are not experienced as existing in objective reality. Auditory pseudohallucinations are suggestive of dissociative disorders. Déjà vu, derealization and depersonalization are associated with temporal lobe epilepsy and dissociative disorders.
Visual hallucinations occur in roughly a third of people with schizophrenia, although rates as high as 55% are reported. Content frequently 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 occur more frequently in various types of encephalopathy (e.g. Peduncular hallucinosis).
According to Evers and Ellgers, some other major psychiatric disorders that contribute to musical hallucinations include schizophrenia and depression. Some patients who have schizophrenia experience musical hallucinations due to their ongoing psychosis, but there are some cases that do so without psychosis. There are also a very small percentage of musical hallucination cases due to obsessive-compulsive disorder (OCD).
In schizophrenia, asociality is one of the main 5 so-called negative symptoms, the others being avolition, anhedonia, reduced affect and alogia. Due to a lack of desire to form relationships, social withdrawal is common in people with schizophrenia. People with schizophrenia may experience social deficits or dysfunction as a result of the disorder, leading to asocial behavior. Frequent or ongoing delusions and hallucinations can deteriorate relationships and other social ties, isolating individuals with schizophrenia from reality and in some cases leading to homelessness. Even when treated with medication for the disorder, they may be unable to engage in social behaviors such as maintaining conversations, accurately perceiving emotions in others, or functioning in crowded settings. There has been extensive research on the effective use of social skills training for the treatment of schizophrenia, in outpatient clinics as well as inpatient units. Social skills training (SST) can be used to help patients with schizophrenia make better eye contact with other people, increase assertiveness, and improve their general conversational skills.
Psychotic symptoms may be present in several other mental disorders, including bipolar disorder, and borderline personality disorder. Delusions ("non-bizarre") are also present in delusional disorder, and social withdrawal in social anxiety disorder, avoidant personality disorder and schizotypal personality disorder. Schizophrenia cannot be diagnosed if symptoms of mood disorder are substantially present, or if symptoms of pervasive developmental disorder are present unless prominent delusions or hallucinations are also present. Schizophrenia is further complicated with obsessive-compulsive disorder (OCD), and it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia. In children hallucinations must be separated from typical childhood fantasies.
Individuals with schizophrenia who display source memory deficits often do so due to reality-monitoring dysfunction, which is a contributing factor towards the hallucinations that characterize the disorder. One study found that schizophrenia patients were not only slower, but also less accurate, at tasks involving reality-monitoring. The hallucinations that characterize schizophrenia are a result of deficit in reality monitoring – they exhibit an inability to differentiate between internally and externally derived information. Overall, there is evidence of a relationship between source monitoring errors and the disorganized thinking that characterizes those who have schizophrenia in that there is a strong tendency for those people with hallucinations to attribute their internally generated events (i.e.: hallucinations and delusions) to an external source (e.g., the experimenter). That is, schizophrenia is characterized by failing to encode themselves as the source of the idea, compounded by attributing these ideas/beliefs to an external source, all of which leads to those individuals with schizophrenia exhibiting behaviours typical of those with source amnesia; they misattribute the source of their knowledge, ideas, or beliefs.
The symptoms of acute amphetamine psychosis are very similar to those of the acute phase of schizophrenia although in amphetamine psychosis visual hallucinations are more common and thought disorder is rare. Amphetamine psychosis may be purely related to high drug usage, or high drug usage may trigger an underlying vulnerability to schizophrenia. There is some evidence that vulnerability to amphetamine psychosis and schizophrenia may be genetically related. Relatives of methamphetamine users with a history of amphetamine psychosis are five times more likely to have been diagnosed with schizophrenia than relatives of methamphetamine users without a history of amphetamine psychosis. The disorders are often distinguished by a rapid resolution of symptoms in amphetamine psychosis, while schizophrenia is more likely to follow a chronic course.
Olfactory and tactile hallucinations correlate with one another in terms of prevalence in patients with schizophrenia. One particular study was conducted by Langdon et al., in which the prevalence of olfactory hallucinations and tactile hallucinations was analyzed in two distinct clinical samples of patients with schizophrenia. One of the samples contained patients with schizophrenia with tactile hallucinations as reported by the World Health Organization while the other sample contained cases with negative and positive types of tactile hallucinations in patients with schizophrenia. It was concluded that about 13% to 17% of patients with schizophrenia experience olfactory and tactile hallucinations. The study reported that socio-cultural factors influenced self-reporting of tactile hallucinations. Since hallucinations in general were feared as a symptoms of insanity, patients were reluctant to seek help for such symptoms. Moreover, the study concluded that tactile hallucinations were usually accompanied by several other hallucinations associated with different modalities such as taste and sight. However, the study failed to recognize the pathophysiology of tactile hallucinations in individuals with schizophrenia.
Auditory hallucinations are the most common "positive symptom" in children. (Positive symptoms have come to mean psychopathological disorders that are actively expressed, such as delusions, hallucinations, thought disorder etc.). A child's auditory hallucinations may include voices that are conversing with each other or voices that are speaking directly to the children themselves. Many children with auditory hallucinations believe that if they do not listen to the voices, the voices will harm them or someone else. Tactile and visual hallucinations seem relatively rare. The children often attribute the hallucinatory voices to a variety of beings, including family members or other people, evil forces ("the Devil", "a witch", "a spirit"), animals, characters from horror movies (Bloody Mary, Freddy Krueger) and less clearly recognizable sources ("bad things," "the whispers"). Command auditory hallucinations (also known as imperative hallucinations) were common and experienced by more than ½ of the group in a research at the Bellevue Hospital Center's Children's Psychiatric Inpatient Unit. And voices repeat and repeat: "Kill somebody!", "Kill her, kill her!". Delusions are reported in more than half of children with schizophrenia, but they are usually less complex than those of adults. Delusions are often connected with hallucinatory experiences. In a research delusions were characterized as persecutory for the most part, but some children reported delusions of control. Many said they were being tortured by the beings causing their visual and auditory hallucinations, some thought disobeying their voices would cause them harm.
Auditory hallucinations attributed to an external source, rather than internal, are considered the defining factor for the diagnoses of schizophrenia. The voices heard are generally destructive and emotive, adding to the state of artificial reality and disorientation seen in psychotic patients. The causal basis of hallucinations has been explored on the cellular receptor level. The glutamate hypothesis, proposed as possible cause for schizophrenia, may also have implications in auditory hallucinations, which are suspected to be triggered by altered glutamatergic transmission.
Paranoid schizophrenia is the most common type of schizophrenia. Schizophrenia is defined as “a chronic mental disorder in which a person loses touch with reality (psychosis)." Schizophrenia is divided into subtypes based on the “predominant symptomatology at the time of evaluation." The clinical picture is dominated by relatively stable and often persecutory delusions that are usually accompanied by hallucinations, particularly of the auditory variety (hearing voices), and perceptual disturbances. These symptoms can have a huge effect on functioning and can negatively affect quality of life. Paranoid schizophrenia is a lifelong disease, but with proper treatment, a person with the illness can attain a higher quality of life.
ORS may be misdiagnosed as schizophrenia. About 13% of schizophrenics have olfactory hallucinations. Generally, schizophrenic hallucinations are perceived as having an imposed, external origin, while in ORS they are recognized as originating from the individual. The suggested diagnostic criteria mean that the possibility of ORS is negated by a diagnosis of schizophrenia in which persistent delusions of an offensive body odor and olfactory hallucinations are contributing features for criterion A. However, some reported ORS cases were presented as co-morbid. Indeed, some have suggested that ORS may in time transform into schizophrenia, but others state there is little evidence for this. Persons with ORS have none of the other criteria to qualify for a diagnosis of schizophrenia.
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. The prevalence in schizophrenia is generally put around 70%, but may go as high as 98%. 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 throughout 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 which may be dangerous when combined with delusions.
People with schizophrenia live with positive, negative, and cognitive symptoms. Positive symptoms (psychotic behaviors that are not present in healthy people): hallucinations, delusions, thought & movement disorders. Negative symptoms (abnormal functioning of emotions and behavior): "flat affect", Anhedonia, reserved. Cognitive symptoms: problems with "executive functioning", attention, and memory. One artist known for his schizophrenia was the Frenchman Antonin Artaud, founder of the Theatre of Cruelty movement. In "Madness and Modernism" (1992), clinical psychologist Louis A. Sass noted that many common traits of schizophrenia – especially fragmentation, defiance of authority, and multiple viewpoints – happen to also be defining features of modern art.
Hallucinations in those with psychoses are often experienced in color, and most often are multi-modal, consisting of visual and auditory components. They frequently accompany paranoia or other thought disorders, and tend to occur during the daytime and are associated with episodes of excess excitability.
The DSM-V lists visual hallucinations as a primary diagnostic criterion for several psychotic disorders, including schizophrenia and schizoaffective disorder. The lifetime prevalence of all psychotic disorders is 3.48% and that of the different diagnostic groups are as follows: 0.87% for schizophrenia, 0.32% for schizoaffective disorder, 0.07% for schizophreniform disorder, 0.18% for delusional disorder, 0.24% for bipolar I disorder, 0.35% for major depressive disorder with psychotic features, 0.42% for substance-induced psychotic disorders, and 0.21% for psychotic disorders due to a general medical condition. Visual hallucinations can occur as a symptom of the above psychotic disorders in 24% to 72% of patients at some point in the course of their illness.
Not all individuals who experience hallucinations have a psychotic disorder. Many physical and psychiatric disorders can manifest with hallucinations, and some individuals may have more than one disorder that could cause different types of hallucinations.
People with schizophrenia may experience hallucinations (most reported are hearing voices), delusions (often bizarre or persecutory in nature), and disorganized thinking and speech. The last may range from loss of train of thought, to sentences only loosely connected in meaning, to speech that is not understandable known as word salad. Social withdrawal, sloppiness of dress and hygiene, and loss of motivation and judgment are all common in schizophrenia.
The occurrence of psychosis in schizophrenia has sometimes been linked to a higher risk of violent acts. Findings on the specific role of delusions or hallucinations have been inconsistent, but have focused on delusional jealousy, perception of threat and command hallucinations. It has been proposed that a certain type of individual with schizophrenia may be most likely to offend, characterized by a history of educational difficulties, low IQ, conduct disorder, early-onset substance misuse and offending prior to diagnosis.
The disorder presents symptoms such as auditory and visual hallucinations, strange thoughts or feelings, and abnormal behavior, profoundly impacting the child's ability to function and sustain normal interpersonal relationships. Delusions are often not systematized and vague. Among the actual psychotic symptoms seen in childhood schizophrenia auditory hallucinations are the most common. They are often presented in relatively simple form of akoasms (auditory hallucinations, such as noise, shots, knocks, etc.). Many of these children also have symptoms of irritability, searching for imaginary objects, or low performance. It typically presents after the age of seven. About 50% of young children diagnosed with schizophrenia experience severe neuropsychiatric symptoms. Studies have demonstrated that diagnostic criteria are similar to those of adult schizophrenia. Diagnosis is based on behavior observed by caretakers and, in some cases depending on age, self reports. Less than 5% of people with schizophrenia see their first symptoms before age 18.
Command hallucinations are hallucinations in the form of commands; they can be auditory or inside of the person's mind or consciousness.[17] The contents of the hallucinations can range from the innocuous to commands to cause harm to the self or others.[17] Command hallucinations are often associated with schizophrenia. People experiencing command hallucinations may or may not comply with the hallucinated commands, depending on the circumstances. Compliance is more common for non-violent commands.[18]
The most prominent features of disorganized schizophrenia are not delusions and hallucinations, as they are in paranoid schizophrenia, although fragmentary delusions, unsystemized and often hypochondriacal, and hallucinations may be present. A person with disorganized schizophrenia may also experience behavioral disorganization, which may impair his or her ability to carry out daily activities such as showering or eating.
During severe episodes of mania or depression people with bipolar disorder may have psychotic symptoms, such as hallucinations or delusions. When experiencing hallucinations or delusions, people with schizophrenia often seem to "lose touch" with reality. "Voices" are the most common type of hallucination in schizophrenia. In bipolar disorder, the psychotic symptoms tend to reflect the person's extreme depressed or elated mood (mood congruence). People with either disorder may have delusions of grandeur in which they believe they are a famous person or historical figure. When psychotic symptoms are present, bipolar disorder is sometimes misdiagnosed as schizophrenia.
Hallucinations of pain and touch are very rare in schizophrenic disorders but 20% of patients with schizophrenia experience some sort of tactile hallucinations along with visual and auditory hallucinations. The most common tactile hallucination in patients with schizophrenia is a sensation in which a patch of their skin is stretched elastically across their head. They vary in intensity, range and speed at which they feel this stretching painful sensation. They are usually triggered by emotional cues such as guilt, anger, fear and depression. Other types of tactile hallucinations takes on a sexual form in patients with schizophrenia. Patients with schizophrenia may sometimes experience the feeling of being kissed or the feeling of someone lying by their side in response to their emotion of being lonely. Additionally, they occasionally hallucinate the feeling of small animals such as snakes crawling over their body. Such vivid tactile sensation of an object that is not present results from the unsuccessful attempt of the brain trying to perceive objects that are novel and that represent unreal situations usually triggered by guilt and fear. Patients with schizophrenia also have a hard time portraying emotions as they divert most of their energy to control the pain from their tactile hallucinations.
Childhood schizophrenia (also known as childhood-onset schizophrenia, and very early-onset schizophrenia) is a schizophrenia spectrum disorder that is characterized by hallucinations, disorganized speech, delusions, catatonic behavior and "negative symptoms", such as inappropriate or blunted affect and avolition with onset before 13 years of age. The term "childhood-onset schizophrenia" and "very early-onset schizophrenia" are used to identify patients in whom the disorder manifests before the age of 13.