Psychosis and substance abuse

ALSO KNOWN AS: Psychosis and substance abuse comorbidity; psychosis and substance abuse dual diagnosis

DEFINITION: Psychosis is defined as an impaired ability to understand reality, think clearly, communicate adequately, and respond emotionally. Hallucinations and delusions (false beliefs) are often present. Psychotic symptoms occur in several mental disorders, such as schizophrenia, bipolar disorder, insomnia, anxiety, and depression. The pathway of association (comorbidity) of psychotic manifestations and substance abuse appears bidirectional, meaning that substance abuse can trigger or exacerbate psychosis, while psychosis may lead to substance abuse. A cycle is thus created, one that often renders diagnosis and treatment difficult.

Substance Abuse and Psychosis

Clinical studies and community surveys document high rates of substance use disorders (SUD) in persons with psychotic symptoms. The lifetime prevalence of substance abuse among persons with psychotic illnesses such as schizophrenia and bipolar disorder is much higher than in the general population.

This comorbidity is most often associated with being male, single, young, and having a conduct or antisocial personality disorder. Persons with psychosis also tend to abuse multiple substances. The overlapping biological substrates responsible for this co-occurrence include structural brain abnormalities, genetic vulnerabilities, and early exposure to stress or trauma.

A high prevalence of substance abuse in persons with schizophrenia is well-established. Individuals with schizophrenia comprise about 1 percent of the population. Among these individuals, between 20 and 65 percent have SUD, which may constitute the most common comorbidity of schizophrenia. Apart from tobacco and cannabis (the preferred substances), individuals with schizophrenia also abuse alcohol and illicit drugs like cocaine and amphetamines.

When a person presents to mental health professionals with recent-onset psychosis associated with substance abuse, it becomes essential to establish whether the substance use caused the symptoms. Psychosis is considered to be independent of the SUD if the psychosis occurred before the substance use or if the psychosis persisted during long substance-free periods. An absence of disorientation (which occurs in substance-induced delirium) may also point to a distinct psychosis. In the twenty-first century, newly emerging substances of abuse increasingly caused episodes of psychosis. Individuals who regularly use illicit substances are at an increased risk of experiencing psychosis resulting from drugs.

In practice, the aforementioned features can be difficult to ascertain. Persons with psychosis often do not remember the exact sequence of events that contributed to the development of their disorder. Therefore, it is difficult to pinpoint the temporal relationship between psychotic symptoms and substance abuse. In addition, the patients may not experience significant substance-free periods. The diagnosis dilemma is further amplified by the similarity of symptoms, such as paranoia and auditory hallucinations, occurring both in independent psychosis and in psychosis induced by substances (especially stimulants). For this reason, persons with comorbid psychosis and SUD need to be thoroughly assessed at presentation, detoxified, treated immediately by interdisciplinary teams (using pharmacotherapy and cognitive behavioral therapy, among other approaches), and then monitored.

Overall, coexisting SUD imparts a more severe character and a poorer outcome to psychotic disorders, with frequent relapses and hospitalizations. Studies show, for example, that persons with defined comorbid SUD and first-episode psychosis are likely to have poorer treatment responses than those with psychosis alone.

Psychosis Triggers

Alcohol and illegal drugs (cannabis, amphetamines, cocaine, hallucinogens, and opiates) can cause psychosis, both during use and as a consequence of withdrawal. Severe psychiatric disorders appear to correlate with earlier and longer exposure to stimulants. This suggests the presence of a critical developmental stage, or a threshold effect, of the drug on psychosis development.

Heavy cannabis use, particularly regular daily use, increases the risk of developing psychotic symptoms. Though further research is needed, some studies indicate that heavy cannabis use, the use of high potency marijuana, or the use of synthetic marijuana leads to the early onset of schizophrenia in individuals predisposed to the condition. Some studies revealed as many as 50 percent of individuals who experience cannabis-induced psychosis are later diagnosed with schizophrenia or bipolar disorder. Cannabis use during adolescence is an independent risk factor for the onset of psychosis in adulthood, especially in at-risk subjects. Studies also suggest that heavy cannabis use precipitates psychotic relapses in persons with schizophrenia who previously achieved remission.

Psychotic symptoms with paranoia and suspiciousness are reported during cocaine use and withdrawal. The propensity to experience cocaine-induced psychosis has been linked to mutations in genes coding for proteins involved in dopaminergic transmission.

Methamphetamine use is commonly associated with psychiatric conditions such as psychosis and depression. During both abstinent and intoxicated circumstances, persons who are methamphetamine-dependent are more likely to report psychotic symptoms than are individuals addicted to cocaine. Drug-induced psychotic syndromes are both positive (auditory hallucinations, persecutory delusions) and negative (poor speech, flattened affect). These psychotic states persist after the pharmacological effects of the methamphetamine have subsided, and they reappear upon reinjection. Furthermore, under stressful conditions, persons with a history of methamphetamine psychosis undergo spontaneous recurrence of their psychotic symptoms. Methamphetamine psychosis might, therefore, be associated with persistent structural or functional brain damage caused by repeated drug administration.

Psychosis Can Lead to Substance Abuse

It has been suggested that persons with schizophrenia may self-medicate with tobacco, alcohol, and drugs. The substances of abuse are often perceived as alleviating negative symptoms (such as depression and withdrawal), improving hallucinations and paranoid delusions, lessening adverse effects of medications (such as restlessness), and providing an avenue for social interaction. This causal relationship remains unclear, as some studies have contradicted the self-medication hypothesis for this comorbidity.

Bibliography

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