Schizophrenia and Addiction

Schizophrenia and personality disorders often overlap with drug or alcohol addiction.¹ Drugs, alcohol and addictive behaviours, like compulsive gambling, are often used as dysfunctional coping mechanisms to help the individual live better with the symptoms of the condition.²

The more an individual uses substances to cope with their symptoms, the greater the risk of developing addiction.² Studies show that approximately half of those who suffer from mental illness also struggle with substance abuse and/or may develop an addiction to drugs or alcohol later in their lives.³ It has been reported that more than 8 million adults (3.4 percent of all adults) with a mental illness abuse drug and/or alcohol, while 2.6 million adults had co-occurring serious mental illness and substance use disorders in the past year.³

However, some evidence suggests that a causative relationship exists between the use of certain drugs and schizophrenic symptoms.⁴ For example, lysergic acid diethylamide (LSD) and other hallucinogenic substances may develop active cases of the disorder,⁵ while marijuana can provoke the onset of schizophrenia in some individuals due to its main active ingredient, tetrahydrocannabinol (THC).⁶ THC exerts a strong effect on the brain, that play an essential role in the human ability to make judgments and form or access memories. When people, regardless of their mental health, smoke or ingest marijuana, they experience disorganization and altered brain function, and subsequently develop temporary versions of several symptoms commonly associated with schizophrenia.⁶ Over time, the neurological effects of the drug may increase the likelihood that the disorder itself will develop, especially in individuals with other significant schizophrenia risks.⁷

Moreover, alcohol use places the individual at an increased risk for acute or chronic harm, and might induce psychotic episodes or worsen a psychiatric disorder.⁸ Alcohol abuse increases the probability to develop schizophrenia more than hallucinogenic substances do.⁹ At the same time, people with schizophrenia who use alcohol or illicit drugs are less motivated to change substance use behaviours, have higher substance use relapse and drop out of treatments at higher rates.¹⁰ Given the prominence of motivation deficits, its association with schizophrenia,¹¹ and the potential link between low motivation and continued substance use,¹⁰ loss of motivation may be one of the most critical factors influencing poorer recovery in those with the disorder, using alcohol and illicit drugs.

In addition, several studies have suggested frequent co-occurrence between psychiatric disorders and disorders of impaired impulse control, including pathological gambling.^12-14 Pathological gambling is associated with arrest, incarceration and other adverse health measures in community samples.¹⁴ Given the many adverse life events, such as financial and family problems caused by gambling, it is expected that individuals with schizophrenia would report a high risk of relapse and hospitalization due to their high vulnerability to stress.¹⁴

It should be noted that some reports have confirmed the existence of pathological gambling in the family lineage of psychiatric patients.¹⁵ However, it is not yet possible to determine whether their co-existence is more likely to happen due to genetic factors, environmental influences or both.¹⁶ Epidemiological data also suggest that pathological gamblers, that are more likely to develop schizophrenia later in their life, tend to be males, young, and possibly of lower socio-economic status. ^17,18

Although multiple medication and behavioural regimens have been investigated in regards to treatment of pathological gambling, studies tend to exclude patients with psychotic disorders.¹⁹
Clinicians should screen for potential gambling-related problems in patients with schizophrenia, particularly those who are either in recovery or actively abusing drugs and/or alcohol. There is a high need for further study of potential risk and protective correlates of problem and pathological gambling in patients suffering from psychotic disorders, while it is also necessary to investigate into effective therapies for these patients.

Finally, the robust association between a wide variety of substances or alcohol abuse and an increased risk of developing schizophrenia later in life, has been reported, even though a causal relationship cannot yet be declared. As part of the ongoing search for interventions to improve substance use outcomes in schizophrenia, a greater focus on motivational deficits, or the relationship between motivation and substance use, may facilitate efforts aimed at fully understanding their relationship and ameliorating treatment outcomes.