Socioeconomic status has also been looked at as a potential cause for personality disorders. There is a strong association with low parental/neighborhood socioeconomic status and personality disorder symptoms. In a recent study comparing parental socioeconomic status and a child's personality, it was seen that children who were from higher socioeconomic backgrounds were more altuistic, less risk seeking, and had overall higher IQs. These traits correlate with a low risk of developing personality disorders later on in life. In a study looking at female children who were detained for disciplinary actions found that psychological problems were most negatively associated with socioeconomic problems. Furthermore, social disorganization was found to be inversely correlated with personality disorder symptoms.

Child abuse and neglect consistently show up as risk factors to the development of personality disorders in adulthood. A study looked at retrospective reports of abuse of participants that had demonstrated psychopathology throughout their life and were later found to have past experience with abuse. In a study of 793 mothers and children, researchers asked mothers if they had screamed at their children, and told them that they did not love them or threatened to send them away. Children who had experienced such verbal abuse were three times as likely as other children (who did not experience such verbal abuse) to have borderline, narcissistic, obsessive-compulsive or paranoid personality disorders in adulthood. The sexually abused group demonstrated the most consistently elevated patterns of psychopathology. Officially verified physical abuse showed an extremely strong correlation with the development of antisocial and impulsive behavior. On the other hand, cases of abuse of the neglectful type that created childhood pathology were found to be subject to partial remission in adulthood.

DID is rarely diagnosed in children, despite the average age of appearance of the first alter being three years. This fact is cited as a reason to doubt the validity of DID, and proponents of both etiologies believe that the discovery of DID in a child that had never undergone treatment would critically undermine the SCM. Conversely, if children are found to only develop DID after undergoing treatment it would challenge the traumagenic model. , approximately 250 cases of DID in children have been identified, though the data does not offer unequivocal support for either theory. While children have been diagnosed with DID before therapy, several were presented to clinicians by parents who were themselves diagnosed with DID; others were influenced by the appearance of DID in popular culture or due to a diagnosis of psychosis due to hearing voices—a symptom also found in DID. No studies have looked for children with DID in the general population, and the single study that attempted to look for children with DID not already in therapy did so by examining siblings of those already in therapy for DID. An analysis of diagnosis of children reported in scientific publications, 44 case studies of single patients were found to be evenly distributed (i.e., each case study was reported by a different author) but in articles regarding groups of patients, four researchers were responsible for the majority of the reports.

The initial theoretical description of DID was that dissociative symptoms were a means of coping with extreme stress (particularly childhood sexual and physical abuse), but this belief has been challenged by the data of multiple research studies. Proponents of the traumagenic hypothesis claim the high correlation of child sexual and physical abuse reported by adults with DID corroborates the link between trauma and DID. However, the DID-maltreatment link has been questioned for several reasons. The studies reporting the links often rely on self-report rather than independent corroborations, and these results may be worsened by selection and referral bias. Most studies of trauma and dissociation are cross-sectional rather than longitudinal, which means researchers can not attribute causation, and studies avoiding recall bias have failed to corroborate such a causal link. In addition, studies rarely control for the many disorders comorbid with DID, or family maladjustment (which is itself highly correlated with DID). The popular association of DID with childhood abuse is relatively recent, occurring only after the publication of "Sybil" in 1973. Most previous examples of "multiples" such as Chris Costner Sizemore, whose life was depicted in the book and film "The Three Faces of Eve", disclosed no history of child abuse.

Little is known about prognosis of untreated DID. It rarely, if ever, goes away without treatment, but symptoms may resolve from time to time or wax and wane spontaneously. Patients with mainly dissociative and posttraumatic symptoms face a better prognosis than those with comorbid disorders or those still in contact with abusers, and the latter groups often face lengthier and more difficult treatment. Suicidal ideation, failed suicide attempts, and self-harm also occur. Duration of treatment can vary depending on patient goals, which can extend from elimination of all alters to merely reducing inter-alter amnesia, but generally takes years.

Individual differences in women's estrogen cycles may be related to the expression of BPD symptoms in female patients. A 2003 study found that women's BPD symptoms were predicted by changes in estrogen levels throughout their menstrual cycles, an effect that remained significant when the results were controlled for a general increase in negative affect.

Another theory suggests a possible relationship between histrionic personality disorder and antisocial personality disorder. Research has found 2/3 of patients diagnosed with histrionic personality disorder also meet criteria similar to those of the antisocial personality disorder, which suggests both disorders based towards sex-type expressions may have the same underlying cause. Women are hypersexualized in the media consistently, ingraining thoughts that the only way women are to get attention is by exploiting themselves, and when seductiveness isn't enough, theatricals are the next step in achieving attention. Men can just as well be flirtatious towards multiple women yet feel no empathy or sense of compassion towards them. They may also become the center of attention by exhibiting the "Don Juan" macho figure as a role-play.

Some family history studies have found that histrionic personality disorder, as well as borderline and antisocial personality disorders, tend to run in families, but it is unclear if this is due to genetic or environmental factors. Both examples suggest that predisposition could be a factor as to why certain people are diagnosed with histrionic personality disorder, however little is known about whether or not the disorder is influenced by any biological compound or is genetically inheritable. Little research has been conducted to determine the biological sources, if any, of this disorder.

There is a strong correlation between child abuse, especially child sexual abuse, and development of BPD. Many individuals with BPD report a history of abuse and neglect as young children, but causation is still debated. Patients with BPD have been found to be significantly more likely to report having been verbally, emotionally, physically, or sexually abused by caregivers of either gender. They also report a high incidence of incest and loss of caregivers in early childhood. Individuals with BPD were also likely to report having caregivers of both sexes deny the validity of their thoughts and feelings. Caregivers were also reported to have failed to provide needed protection and to have neglected their child's physical care. Parents of both sexes were typically reported to have withdrawn from the child emotionally and to have treated the child inconsistently. Additionally, women with BPD who reported a previous history of neglect by a female caregiver and abuse by a male caregiver were significantly more likely to experience sexual abuse by a non-caregiver.

It has been suggested that children who experience chronic early maltreatment and attachment difficulties may go on to develop borderline personality disorder. Writing in the psychoanalytic tradition, Otto Kernberg argues that a child's failure to achieve the developmental task of and failure to overcome splitting might increase the risk of developing a borderline personality. A child's inability to tolerate delayed gratification at age four does not predict later development of BPD.

Approximately 1–3% of the general population may be diagnosed with HPD. Major character traits may be inherited, while other traits may be due to a combination of genetics and environment, including childhood experiences. This personality is seen more often in women than in men. It has typically been found that at least two thirds of persons with HPD are female, however there have been a few exceptions. Whether or not the rate will be significantly higher than the rate of women within a particular clinical setting depends upon many factors that are mostly independent of the differential sex prevalence for HPD. Those with HPD are more likely to look for multiple people for attention which leads to marital problems due to jealousy and lack of trust from the other party. This makes them more likely to become divorced or separated once married.

Neurosis is a class of functional mental disorders involving chronic distress but neither delusions nor hallucinations. The term is no longer used by the professional psychiatric community in the United States, having been eliminated from the "Diagnostic and Statistical Manual of Mental Disorders" in 1980 with the publication of DSM III. It is still used in the .

Neurosis should not be mistaken for psychosis, which refers to a loss of touch with reality. Neither should it be mistaken for neuroticism, a fundamental personality trait proposed in the big Five personality traits theory.

Pseudoneurotic schizophrenia is a postulated mental disorder categorized by the presence of two or more symptoms of mental illness such as anxiety, hysteria, and phobic or obsessive-compulsive neuroses. It is often acknowledged as a personality disorder. Patients generally display salient anxiety symptoms that disguise an underlying psychotic disorder.

In the 1940s, psychiatrists Paul Hoch and Philip Polatin created the term pseudoneurotic schizophrenia. This mental illness, however, is no longer acknowledged as a clinical entity. In 1972 it went on to be called borderline personality disorder, a term coined by Otto Friedmann Kernberg, which referred to an expansive range of issues.

Pseudoneurotic schizophrenia is in the Russian adapted version of the ICD-10 (code F21.3).

Examples from a 295-subject study in Lithuania showed that the most common religious delusions were being a saint (in women) and being God (in men).

In one study of 193 people who had previously been admitted to hospital and subsequently diagnosed with schizophrenia, 24% were found to have religious delusions.

A 1999 study identified that religious delusions were often present or expressed in persons with forensic committal to a psychiatric unit.

There are many different neuroses: obsessive–compulsive disorder, obsessive–compulsive personality disorder, impulse control disorder, anxiety disorder, hysteria, and a great variety of phobias.

According to C. George Boeree, professor emeritus at Shippensburg University, the symptoms of neurosis may involve:

Neurosis may be defined simply as a "poor ability to adapt to one's environment, an inability to change one's life patterns, and the inability to develop a richer, more complex, more satisfying personality."

Zou huo ru mo (走火入魔) or "qigong deviation" (气功出偏), is a Chinese term traditionally used to indicate that something has gone wrong in spiritual or martial arts training, applied to describe a physiological or psychological disorder believed to result during or after qigong practice, believed by the qigong community to result from "improper practice" of qigong and other self-cultivation techniques, and highlighted in the social and political context of mass popularization of qigong in China.

Sluggish schizophrenia or slow progressive schizophrenia (, "vyalotekushchaya shizofreniya") was a diagnostic category used in Soviet Union to describe what they claimed was a form of schizophrenia characterized by a slowly progressive course; it was diagnosed even in a patient who showed no symptoms of schizophrenia or other psychotic disorders, on the assumption that these symptoms would appear later. It was developed in the 1960s by Soviet psychiatrist Andrei Snezhnevsky and his colleagues, and was used exclusively in the USSR and several Eastern Bloc countries, until the fall of Communism starting in 1989. The diagnosis has long been discredited because of its scientific inadequacy and its use as a means of confining dissenters. It has never been used or recognized outside of Soviet Union, or by international organizations such as the World Health Organization. It is considered a prime example of the political abuse of psychiatry in the Soviet Union.

Sluggish schizophrenia was the most infamous of diagnoses used by Soviet psychiatrists, due to its usage against political dissidents. After being discharged from a hospital, persons diagnosed with sluggish schizophrenia were deprived of their civic rights, credibility and employability. The usage of this diagnosis has been internationally condemned.

In the Russian version of the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10), which has long been used throughout present-day Russia, sluggish schizophrenia is no longer listed as a form of schizophrenia, but it is still included as a schizotypal disorder in section F21 of chapter V.

According to Sergei Jargin, the same Russian term "vyalotekushchaya" for sluggish schizophrenia continues to be used and is now translated in English summaries of articles not as "sluggish" but as "slow progressive".

Individuals experiencing religious delusions are preoccupied with religious subjects that are not within the expected beliefs for an individual's background, including culture, education, and known experiences of religion. These preoccupations are incongruous with the mood of the subject. Falling within the definition also are delusions arising in psychotic depression; however, these must present within a major depressive episode and be congruous with mood.

Researchers in a 2000 study found religious delusions to be unrelated to any specific set of diagnostic criteria, but correlated with demographic criteria, primarily age. In a comparative study sampling 313 patients, those with religious delusion were found to be aged older, and had been placed on a drug regime or started a treatment programme at an earlier stage. In the context of presentation, their global functioning was found to be worse than another group of patients without religious delusions. The first group also scored higher on the Scale for the Assessment of Positive Symptoms (SAPS), had a greater total on the Brief Psychiatric Rating Scale (BPRS), and were treated with a higher mean number of neuroleptic medications of differing types during their hospitalization.

Religious delusion was found in 2007 to strongly correlate with "temporolimbic overactivity". This is a condition where irregularities in the brain's limbic system may present as symptoms of paranoid schizophrenia.

In a 2010 study, Swiss psychiatrists found religious delusions with themes of spiritual persecution by malevolent spirit-entities, control exerted over the person by spirit-entities, delusional experience of sin and guilt, or delusions of grandeur.

Religious delusions have generally been found to be less stressful than other types of delusion. A study found adherents to new religious movements to have similar delusionary cognition, as rated by the Delusions Inventory, to a psychotic group, although the former reported feeling less distressed by their experiences than the latter.

When pseudoneurotic schizophrenia was still being utilized as a diagnostic term, doctors were expected to be able to magically cure patients. Patients usually had very little understanding of themselves and the complexity of their illness. They were willing to employ any process in order to maintain mental stability. Their perception of mental stability, however, was also impaired, which made it much more difficult to make proper, helpful medication prescriptions.

Patients would often misuse medication in order to receive attention from their families. They would describe the dosage and effects of the medicine in some strange demeanor to demonstrate that their illness was physical rather than psychological. In like manner, taking medication also kept doctors concerned about the possibility of the patient developing substance dependence and/or drug addiction. Patients used this to get attention and sympathy from others.

The Chinese word "zǒuhuǒrùmó" "①be obsessed with sth. ②possessed by the Devil" combines "zǒuhuǒ(r)" "①〈elec.〉 ⓐspark ⓑhave a short circuit ②〈coll.〉 discharge (a firearm) accidentally ③overstate ④catch fire; be on fire" and "rùmó" "①be spellbound ②be infatuated/obsessed". In recent times this syndrome has been known as "qìgōngpiānchā" 氣功偏差 "qigong deviation/error". The term has traditionally been applied to indicate that something has gone wrong in one's martial arts training, interpreted as "imbalance of qi (life energy)". In more recent history, the term has been applied to refer to undesirable somatic or psychological effects experienced during or after the practice of the broad range of Chinese self-cultivation exercises known as qigong. Most cases do not last for an extended period of time, and are never brought to medical attention. While qigong may act as a stressor in vulnerable individuals, relations between qigong and disorders are manifold, and causal relationships have not been demonstrated. Similar syndromes have been observed in other forms of self-cultivation practices such as yoga (Kundalini syndrome), meditation, and hypnosis.

Pyrophilia is a relatively uncommon paraphilia in which a subject derives gratification from fire and fire-starting activity. It is distinguished from pyromania by the gratification being of a sexual nature.

The condition was explained as being a result of exhaustion of the central nervous system's energy reserves, which Beard attributed to modern civilization. Physicians in the Beard school of thought associated neurasthenia with the stresses of urbanization and with stress suffered as a result of the increasingly competitive business environment. Typically, it was associated with upper class people and with professionals working in sedentary occupations, but really can apply to anyone who lives within the monetary system.

Freud included a variety of physical symptoms in this category, including fatigue, dyspepsia with flatulence, and indications of intra-cranial pressure and spinal irritation. In common with some other people of the time, he believed this condition to be due to "non-completed coitus" or the non-completion of the higher cultural correlate thereof, or to "infrequency of emissions" or the infrequent practice of the higher cultural correlate thereof. Later, Freud formulated that in cases of coitus interruptus as well as in cases of masturbation, there was "an insufficient libidinal discharge" that had a poisoning effect on the organism, in other words, neurasthenia was the result of (auto-)intoxication. Eventually he separated it from anxiety neurosis, though he believed that a combination of the two conditions existed in many cases.

Neurasthenia is a term that was first used at least as early as 1829 to label a mechanical weakness of the "nerves" and would become a major diagnosis in North America during the late nineteenth and early twentieth centuries after neurologist George Miller Beard reintroduced the concept in 1869.

As a psychopathological term, the first to publish on neurasthenia was Michigan alienist E. H. Van Deusen of the Kalamazoo asylum in 1869, followed a few months later by New York neurologist George Beard, also in 1869 to denote a condition with symptoms of fatigue, anxiety, headache, heart palpitations, high blood pressure, neuralgia, and depressed mood. Van Deusen associated the condition with farm wives made sick by isolation and a lack of engaging activity, while Beard connected the condition to busy society women and overworked businessmen.

Neurasthenia is currently a diagnosis in the World Health Organization's International Classification of Diseases (and the Chinese Society of Psychiatry's Chinese Classification of Mental Disorders). However, it is no longer included as a diagnosis in the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders".

Americans were said to be particularly prone to neurasthenia, which resulted in the nickname "Americanitis" (popularized by William James). Another, rarely used, term for neurasthenia is nervosism.

Secondary organic delusional parasitosis occurs when the state of the patient is caused by a medical illness or substance (medical or recreational) use. In the DSM-IV this corresponds with "psychotic disorder due to general medical condition". Physical illnesses that can underlie secondary organic delusional parasitosis include: hypothyroidism, cancer, cerebrovascular disease, tuberculosis, neurological disorders, vitamin B12 deficiency, and diabetes mellitus. Any illness or medication for which formication is a symptom or side effect can become a trigger or underlying cause of delusional parasitosis.

Other physiological factors which can cause formication and thus can sometimes lead to this condition include: menopause (i.e. hormone withdrawal); allergies, and drug abuse, including but not limited to cocaine and methamphetamine (as in amphetamine psychosis). It appears that many of these physiological factors, as well as environmental factors such as airborne irritants, are capable of inducing a "crawling" sensation in otherwise healthy individuals; however, some people become fixated on the sensation and its possible meaning, and this fixation may then develop into delusional parasitosis.

Methamphetamine induces a psychosis in 26–46 percent of heavy users. Some of these people develop a long-lasting psychosis that can persist for longer than six months. Those who have had a short-lived psychosis from methamphetamine can have a relapse of the methamphetamine psychosis years later after a stress event such as severe insomnia or a period of heavy alcohol abuse despite not relapsing back to methamphetamine. Individuals who have long history of methamphetamine abuse and who have experienced psychosis in the past from methamphetamine abuse are highly likely to rapidly relapse back into a methamphetamine psychosis within a week or so of going back onto methamphetamine.

As it has already been mentioned, patients with organic personality disorder show a wide variety of sudden behavioural changes and dysfunctions. There are not a lot of information about the treatment of this mental health disorder. The pharmacological approach is the most common therapy among patients with organic personality disorder. However, the choice of drug therapy relies on the seriousness of patient's situation and what symptoms are shown. The choice and administration of specific drugs contribute to the reduction of symptoms of organic personality disorder. For this reason, it is crucial for patients' treatment to be assessed by clinical psychologists and psychiatrists before the administration of drug.

Additionally, the dysfunctions in expression of behaviour of patients with organic personality disorder and the development of symptom of irritability, which are caused by aggressive and self-injurious behaviours, can be dealt with the administration of carbamazepine. Moreover, the symptoms of this disorder can be decreased by the administration of valproic acid. Also, emotional irritability and signs of depression can be dealt with the use of nortriptyline and low-dose thioridazine. Except from the symptom of irritability, patients express aggressive behaviours. At the onset of drug therapy for effective treatment of anger and aggression, the drug of carbamazepine, phenobarbital, benztropine and haloperidol can be administrated in order to reduce the symptoms of patients with organic personality disorder. In addition, the use of propranolol may decrease the frequent behaviours of rage attacks.

Finally, it is important for patients to take part in psychotherapy sessions during the period of drug therapy. In this way, there is prevention and patients can be protected by negative effects of drugs on their organism and their behaviour. Furthermore, the clinicians can provide useful and helpful support to patients during these psychotherapy sessions. Thus, the combination of drug therapy with psychotherapy can lead to the reduction of symptoms of this disorder and the improvement of patients' situation.

According to some studies, the more often cannabis is used the more likely a person is to develop a psychotic illness, with frequent use being correlated with twice the risk of psychosis and schizophrenia. While cannabis use is accepted as a contributory cause of schizophrenia by some, it remains controversial, with pre-existing vulnerability to psychosis emerging as the key factor that influences the link between cannabis use and psychosis. Some studies indicate that the effects of two active compounds in cannabis, tetrahydrocannabinol (THC) and cannabidiol (CBD), have opposite effects with respect to psychosis. While THC can induce psychotic symptoms in healthy individuals, CBD may reduce the symptoms caused by cannabis.

Cannabis use has increased dramatically over the past few decades whereas the rate of psychosis has not increased. Together, these findings suggest that cannabis use may hasten the onset of psychosis in those who may already be predisposed to psychosis. High-potency cannabis use indeed seems to accelerate the onset of psychosis in predisposed patients. A 2012 study concluded that cannabis plays an important role in the development of psychosis in vulnerable individuals, and that cannabis use in early adolescence should be discouraged.

As it has already been mentioned, the organic personality disorder is included in a wide group of personality and behavioural disorders. This mental health disorder can be caused by disease, brain damages or dysfunctions in specific brain areas in frontal lobe. The most common reason for this profound change in personality is the traumatic brain injury (TBI). Children, whose brain areas have injured or damaged, may present Attention Deficit Hyperactivity Disorder (ADHD), oppositional defiant disorder (ODD) and organic personality disorder. Moreover, this disorder is characterised as "frontal lobe syndrome". This characteristic name shows that the organic personality disorder can usually be caused by lesions in three brain areas of frontal lobe. Specifically, the symptoms of organic personality disorder can also be caused by traumatic brain injuries in orbitofrontal cortex, anterior cingulate cortex and dorsolateral prefrontal cortex. It is worth to be mentioned that organic personality disorder may also be caused by lesions in other circumscribed brain areas.