Violence
Despite public or media opinion, national studies have indicated that severe mental illness does not independently predict future violent behavior, on average, and is not a leading cause of violence in society. There is a statistical association with various factors that do relate to violence (in anyone), such as substance use and various personal, social, and economic factors.[220] A 2015 review found that in the United States, about 4% of violence is attributable to people diagnosed with mental illness,[221] and a 2014 study found that 7.5% of crimes committed by mentally ill people were directly related to the symptoms of their mental illness.[222] The majority of people with serious mental illness are never violent.[223]
In fact, findings consistently indicate that it is many times more likely that people diagnosed with a serious mental illness living in the community will be the victims rather than the perpetrators of violence.[224][225] In a study of individuals diagnosed with "severe mental illness" living in a US inner-city area, a quarter were found to have been victims of at least one violent crime over the course of a year, a proportion eleven times higher than the inner-city average, and higher in every category of crime including violent assaults and theft.[226] People with a diagnosis may find it more difficult to secure prosecutions, however, due in part to prejudice and being seen as less credible.[227]
However, there are some specific diagnoses, such as childhood conduct disorder or adult antisocial personality disorder or psychopathy, which are defined by, or are inherently associated with, conduct problems and violence. There are conflicting findings about the extent to which certain specific symptoms, notably some kinds of psychosis (hallucinations or delusions) that can occur in disorders such as schizophrenia, delusional disorder or mood disorder, are linked to an increased risk of serious violence on average. The mediating factors of violent acts, however, are most consistently found to be mainly socio-demographic and socio-economic factors such as being young, male, of lower socioeconomic status and, in particular, substance use (including alcohol use) to which some people may be particularly vulnerable.[62][224][228][229]
High-profile cases have led to fears that serious crimes, such as homicide, have increased due to deinstitutionalization, but the evidence does not support this conclusion.[229][230] Violence that does occur in relation to mental disorder (against the mentally ill or by the mentally ill) typically occurs in the context of complex social interactions, often in a family setting rather than between strangers.[231] It is also an issue in health care settings[232] and the wider community.[233]
Mental health
Main article: Mental health
The recognition and understanding of mental health conditions have changed over time and across cultures and there are still variations in definition, assessment, and classification, although standard guideline criteria are widely used. In many cases, there appears to be a continuum between mental health and mental illness, making diagnosis complex.[41]: 39 According to the World Health Organization, over a third of people in most countries report problems at some time in their life which meet the criteria for diagnosis of one or more of the common types of mental disorder.[130] Corey M Keyes has created a two continua model of mental illness and health which holds that both are related, but distinct dimensions: one continuum indicates the presence or absence of mental health, the other the presence or absence of mental illness.[234] For example, people with optimal mental health can also have a mental illness, and people who have no mental illness can also have poor mental health.[235]
Other animals
Main article: Animal psychopathology
Psychopathology in non-human primates has been studied since the mid-20th century. Over 20 behavioral patterns in captive chimpanzees have been documented as (statistically) abnormal for frequency, severity or oddness—some of which have also been observed in the wild. Captive great apes show gross behavioral abnormalities such as stereotypy of movements, self-mutilation, disturbed emotional reactions (mainly fear or aggression) towards companions, lack of species-typical communications, and generalized learned helplessness. In some cases such behaviors are hypothesized to be equivalent to symptoms associated with psychiatric disorders in humans such as depression, anxiety disorders, eating disorders and post-traumatic stress disorder. Concepts of antisocial, borderline and schizoid personality disorders have also been applied to non-human great apes.[236][237]
The risk of anthropomorphism is often raised concerning such comparisons, and assessment of non-human animals cannot incorporate evidence from linguistic communication. However, available evidence may range from nonverbal behaviors—including physiological responses and homologous facial displays and acoustic utterances—to neurochemical studies. It is pointed out that human psychiatric classification is often based on statistical description and judgment of behaviors (especially when speech or language is impaired) and that the use of verbal self-report is itself problematic and unreliable.[236][238]
Psychopathology has generally been traced, at least in captivity, to adverse rearing conditions such as early separation of infants from mothers; early sensory deprivation; and extended periods of social isolation. Studies have also indicated individual variation in temperament, such as sociability or impulsiveness. Particular causes of problems in captivity have included integration of strangers into existing groups and a lack of individual space, in which context some pathological behaviors have also been seen as coping mechanisms. Remedial interventions have included careful individually tailored re-socialization programs, behavior therapy, environment enrichment, and on rare occasions psychiatric drugs. Socialization has been found to work 90% of the time in disturbed chimpanzees, although restoration of functional sexuality and caregiving is often not achieved.[236][239]
Laboratory researchers sometimes try to develop animal models of human mental disorders, including by inducing or treating symptoms in animals through genetic, neurological, chemical or behavioral manipulation,[240][241] but this has been criticized on empirical grounds[242] and opposed on animal rights grounds.