1.3 The relationship between substance use and mental health problems

A Family Guide to Concurrent Disorders - Part I: What are concurrent disorders?

Do the substance use behaviours cause psychiatric symptoms? Do the mental health issues lead people to use substances to relieve troubled mental states? The relationship is usually much more complicated than simple cause and effect. Researchers have suggested four types of interaction:

• substance use and mental health problems may be triggered by the same factor
• mental health problems may influence the development of substance use problems
• substance use problems may influence the development of mental health problems
• substance use and mental health problems may not interact.

The way substance use and mental health problems interact is specific to the person, the mental health problem and the substance being used, and may change over time.

Substance use and mental health problems may be triggered by the same factor

Both substance use and mental health problems could be caused by a common factor, that could be genetic, developmental or environmental. For example, traumatic events (an environmental factor) can lead to both mental health and substance use problems.

Mental health problems may influence the development of substance use problems

Severe mental health problems, such as schizophrenia or bipolar disorder, may leave people more vulnerable to developing substance use problems; they tend to develop substance use problems with lower amounts of alcohol or other drug use than people who don't have mental health problems.

People may use substances in the hope of relieving the symptoms of mental health problems. For example, someone with an anxiety disorder may use alcohol to feel more at ease in social situations. This is called self-medication.

Substance use problems may influence the development of mental health problems

Substance use can induce psychiatric symptoms. For example, a person using significant amounts of cocaine could become paranoid to the point of being psychotic.

Substance use can not only induce psychiatric symptoms, but can also lead to psychosocial problems that may in turn lead to mental health problems. Severe paranoia could lead to psychosocial problems such as trouble in family relationships, trouble at work and trouble with the law. These problems could lead to a mental health problem such as depression.

Substance use and mental health problems may not interact

Sometimes, both mental health and substance use problems are present, but do not interact, so that even when one problem area is addressed, the other problem area is still active.

For some people, getting substance use under control will produce immediate positive changes in mental health symptoms. For others, it can mean that their mental health symptoms become more active. Understanding the relationship between the substance use and mental health problems is key to working successfully with people to choose treatment strategies and anticipate outcomes.

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