Text adapted in 2021 from The Fundamentals of Addiction in The Primary Care Addiction Toolkit (online only). A complete list of Toolkit authors, editors and contributors is available here.
Please note: Concurrent Disorders are also known in Canada as Co-Occuring Disorders.
Relationship Between Mental Health and Substance Use Problems
- Mental health and substance use problems interact in various ways:
- Alcohol and other drugs are effective short-term anxiolytics and are often used to self-medicate symptoms of anxiety.
- People with alcohol or other drug problems often attribute withdrawal symptoms to anxiety.
- Alcohol and other drugs tend to exacerbate co-existing primary psychiatric disorders. For example, cannabis worsens symptoms of schizophrenia and can precipitate a psychotic episode.
- Alcohol is often responsible for depressive symptoms (alcohol-induced mood disorder) in people with alcohol dependence.
- All of the major drugs can cause substance-induced psychiatric disorders, particularly mood and anxiety disorders.
- People with primary psychiatric disorders can develop substance-induced disorders. For example, someone with an anxiety disorder can develop alcohol-induced depression.
- Substance use can interfere with treatment of the primary psychiatric disorder in various ways:
- People who use substances are less likely to adhere to psychiatric pharmacotherapy.
- Substances may interact with psychiatric medications.
- Substance use can contribute to behavioural problems and interpersonal difficulties.
A co-existing substance use disorder and primary psychiatric disorder is known as a concurrent disorder.
Given the high rates of co-occurring mental health and substance use problems, all patients presenting with a mood, anxiety or psychotic disorder should be screened for substance use, and all patients with a substance use disorder should be screened for depression, anxiety, psychosis and a history of trauma.
Substance-Induced Psychiatric Disorders
A psychiatric disorder is more likely to be substance-induced if:
- the psychiatric symptoms developed during or within a month of substance intoxication or withdrawal
- the substance used is known to cause symptoms of anxiety, depression or psychosis
- the symptoms resolve with abstinence
- the symptoms cannot be better explained by a disorder that is not substance induced.
Table 1: Clinical Features of Primary and Substance Use Disorders
Onset of symptoms precedes substance use
Use is heavy or often enough to explain symptoms
Symptoms resolve with abstinence
Yes, within days to months
Patient uses substances for symptom control
Suicide Risk with Co-occurring Disorders
People with substance-induced disorders have a higher risk for suicide, particularly during acute intoxication and withdrawal. These patients should be carefully assessed, observed and, if necessary, admitted to hospital.
Often a patient's mental state improves within 24 to 48 hours of abstinence, which helps to distinguish between substance-induced symptoms and primary psychiatric problems.
Antidepressants and intensive treatment for substance dependence should be initiated in patients with concurrent depression.
In Fundamentals of Addiction:
- Defining Addiction
- Key Concepts in Addiction
- Implications for Clinical Practice
- Intoxication & Driving
- Identifying Concurrent Disorders
- Motivation and change