Understanding the Relationship between Substance Use Disorders and Psychosis

  1. Can Substance Abuse Causes Psychosis?

When it comes to the question of whether substance use can cause psychosis or psychotic illness the substances that are at the forefront of such a discussion are stimulants, cannabis, and hallucinogens (Phillips, et al., 2010).

  1. Cannabis and Psychosis

Among these classes of substances mentioned above cannabis is the most studied and the most discussed by researchers to have the potential to cause psychosis or psychotic illness. This research interest has been on for more than 100 years but it is from the 1960s that the focus of researchers was directed towards investigating the relationship between cannabis use and acute psychosis and schizophrenia as a disease. Studies do show that heavy use of cannabis results in acute intoxication which rise to a condition known as cannabis psychosis – this is a condition that results from heavy use of cannabis or acute intoxication causing individuals to experience psychotic symptoms that last for a few days with features such as hallucinations, delusions, loss of short-term memory and confusion (Hamilton, 2017; Phillips, et al., 2010). Putting together all the body of research findings regarding the relationship between cannabis use and psychosis it can be said that there is ample evidence to support the fact that one of the long-term effects of cannabis use is associated with the development of psychotic symptoms and schizophrenia (Tucker, 2009).

  1. Methamphetamine and Psychosis

It has been generally accepted by researchers that Amphetamine use can potentially produce impermanent psychotic symptoms among its users, though this is not common among all Amphetamine users. Some of the factors that have been found to make Amphetamine users susceptible to psychosis are early age of first use, heavier use, presence of schizoid and schizotypal traits, depression, alcohol dependence, and antisocial personality disorder (Tucker, 2009). Amongst several studies on stimulants or Amphetamine and psychosis, there is a consensus that up to 10% of chronic Amphetamine users do manifest chronic psychotic features that can last for several months. Findings from several studies also demonstrate the fact that those who gain abstinence from Amphetamine use when they return to start using again, even just a single dose of Amphetamine they end developing paranoia and other psychotic symptoms (Phillips, et al., 2010).

  1. Alcohol use and Psychosis

Although heavy alcohol use is often associated with the early onset of psychosis, and most of the co-occurring disorders diagnosed cases, it is worth mentioning that the level of attention given to this in terms of research works are relatively few (Tucker, 2009). When a longitudinal study was conducted by Barrowclough and colleagues (2014) to investigate the relationship between alcohol use and the clinical outcomes of patients diagnosed with psychosis, they found out that, as individuals change their alcohol consumption the severity of their depressive symptoms is affected and not anxiety. Therefore, they concluded that alcohol consumption does not cause psychosis. Although several studies do show that those with an early onset of psychosis turn to engage in heavy use of substances, particularly cannabis and alcohol.

When it comes to the question can substance use causes psychosis, it is worth stating that there are studies that provide conclusive evidence supporting the theory that cannabis use causes schizophrenia and psychosis, and also coming as a distant second is Amphetamine.

  1. A Description of Alcohol and Drug Use-Related Psychotic-Like Symptoms

The heavy use of a substance, for example, cannabis results in the experiencing of symptoms that mimic psychosis and these symptoms can last for several days depending on the drug half-life (Phillips, et al., 2010). Acute intoxication by various substances has been found to produce psychotic-like symptoms such as hallucinations and delusions features. Several community surveys show these psychotic experiences are bidirectional (Degenhardt, et al., 2018).

Phillips and colleagues (2010) described drug use-related psychotic symptoms by highlighting Poole and Barbbins (1996) proposed seven-point model with the following descriptions:

  • Heavy use of substances leads to intoxication which results in symptoms that mimic psychosis especially substances such as stimulants and cannabis.
  • Substances such as cannabis have been found to significantly affect the severity and frequency of psychotic features for patients diagnosed with a psychotic illness such as schizophrenia.
  • Heavy alcohol use, cannabis, and LSDs have been found to leave their users to develop chronic hallucinations.
  • It has been shown from the findings of studies that there is a direct link between substance use and relapse in psychotic illness. As a result, patients have been found to self-medicate as a way for them to seek to reduce their symptoms, and their cognition affected resulting in impairment in judgment and relapse.
  • Withdrawal from heavy alcohol use and benzodiazepine is associated with the development of Delirium Tremens (DT) which is not a psychotic illness but does manifest psychotic-like symptoms such as hallucinations and clouding of judgment.
  • Drug-induced psychosis occurs in cases where there is a history of heavy drug use with symptoms lasting for days or weeks and symptoms continue to persist even when the substance has been eliminated from the body. What distinguishes drug-0induced psychosis from a normal clinical psychotic illness is that the psychotic symptoms subside or are eliminated when the patient gains abstinence.
  • Hallucinogen and cannabis users do experience panic and extreme anxiety symptoms, and stimulant users also experience depressive symptoms which oftentimes are being mistaken for psychotic symptoms. During the state of intoxication substance, users do experience a range of psychotic-like symptoms which include hallucination, paranoid ideation, and agitation.
  1. Self-medication and the Development of Substance Use Disorder

Generally speaking, it is very common to see among those who seek therapeutic help for their psychiatric problems such as depression, anxiety, trauma, and PTSD also to present a history of substance use or dependence, or sometimes down the road in their treatment develop comorbid substance use disorder. The argument made by these patients for self-medicating is that their use of drugs helps to reduce their pain, stabilize their mood, help them better manage the stress and discomfort associated with psychotic illness (Levy, 2019; Robinson, et al., 2011). Robinson and colleagues (2011) in the research on the Role of self-medication in the development of comorbid anxiety and substance use disorders from the evidence gathered were able to conclude that self-medication is cardinal as a risk factor for the development of the Role of self-medication in the development of comorbid anxiety and substance use disorders as were the case of those they surveyed diagnosed with an anxiety disorder, this was not the case when compared with individuals diagnosed with an anxiety disorder but have no history of self-medication.

  1. Factors Associated with the Development of Mental Illness and/or Substance Use Disorder

From the findings of several studies on mental health and substance use researchers have been able to identify factors associated with the development of mental illness and/or substance use disorders, this includes; genetic vulnerabilities, epigenetic influences, brain region involvement, and environmental influences (NIDA, 2018, February 27).

  • Genetic vulnerabilities; studies have shown that genetic variants cause vulnerabilities that can directly or indirectly influence the development of mental health illness or substance use disorders.
  • Epigenetic influences; experiences such as stress, trauma, and other environmental factors can cause changes in the protein structure, expression, and function of genes thus increasing the likelihood of individuals developing substance use or mental health disorders.
  • Environmental influences; factors such as stress and trauma causes individuals to predispose to the development of mental illness and substance use as they often will turn to self-medicate to deal with pain, whether emotional or physical, the trauma of their physical, sexual and verbal abuse.
  • Social influences; peer pressure, social problems or difficulties such as homelessness, joblessness, poor education and lack of skills, lack of social network and support, dysfunctional families do have the potential to increase the likelihood for individuals to engage in substance use or continuation of drug use which can also lead to the development of mental health disorder

Effective Treatment Approaches for Dually Diagnosed Patients with Psychosis and a Substance Use Disorder

Psychosis is characterized by hallucinations, delusions, and disorganized behavior and thinking. Patients with co-occurring substance use disorder and psychosis can be best treated by using an integration of pharmacology and psychotherapy interventions (Akerman, et al., 2014).

  1. Pharmacotherapy; studies show that Clozapine is very effective in treating co-occurring schizophrenia and substance use disorder. Other medications are equally effective. Naltrexone is effective at reducing alcohol dependency thus enhancing the chances of recovery for co-occurring alcohol use and psychotic patients; Acamprosate is effective at reducing the risk of relapse after detoxing from alcohol thus helpful in gaining long-term abstinence. For a patient having comorbid Major Depression Disorder and substance use disorder, the following antidepressants such as sertraline, fluoxetine, venlafaxine, and mirtazapine have proven to be very effective (Salloum, & Brown, 2017).
  2. Psychotherapy; Integration of Motivational Interviewing and Cognitive Behavioral Therapy (MI-CBT) has been seen to be very effective in treating individuals diagnosed with substance use and psychosis. As a treatment approach, it has been to effectively address the complex and dynamic relationship between co-occurring substance use and the severity of psychotic symptoms, motivation for change, and the issue of patient’s ambivalence to engage in treatment (Jones, et al., 2018). This treatment approach is divided into three phases;
  3. Phase one; both individual and group sessions focus on helping a patient to cultivate self-change talk using motivational interviewing techniques.
  4. Phase two; both individual and group sessions seek to help the patient come up with a specific individualized change plan that spells out their alcohol reduction/abstinence plan.
  • Phase three; sessions focus more on using CBT techniques to help patients develop skills to manage symptoms associated with their mood disorders


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Co-Occurring Schizophrenia and Substance Use Disorders. Current Addiction Reports, 1(4), 251. https://doi-org.proxy1.ncu.edu/10.1007/s40429-014-0034-7

Barrowclough, C., Eisner, E., Bucci, S., Emsley, R., & Wykes, T. (2014). The impact of alcohol on

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(2018). The associations between psychotic experiences and substance use and substance use disorders: findings from the World Health Organization World Mental Health surveys. Addiction, 113(5), 924–934. Retrieved from https://search-ebscohost-com.proxy1.ncu.edu/login.aspx?direct=true&db=s3h&AN=129015743&site=eds-live

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Addiction, 112(9), 1653–1657. https://doi-org.proxy1.ncu.edu/10.1111/add.13826

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NIDA. (2018, February 27). Common Comorbidities with Substance Use Disorders.

https://www.drugabuse.gov/publications/research-reports/common-comorbidities-substance-use-disorders on 2019, December 25

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UK: Wiley-Blackwell

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Tucker, P. (2009). Substance misuse and early psychosis. Australasian Psychiatry, 17(4),

291–294. https://doi-org.proxy1.ncu.edu/10.1080/10398560802657314

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