National Drug Strategy
National Drug Strategy

Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician

12.5 Does brain injury predispose individuals to substance use?

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The relationship between brain injury and post-brain injury substance use (including alcohol, cannabis and other illicit substances) is still unclear and, as mentioned, causality remains uncertain. Those with a brain injury have been shown to have higher lifetime rates of substance use than those without(506).

On the other hand, there is some evidence that rates of post-brain injury substance use does not increase(508, 514) and, in fact, may even decline(504). However, post-brain injury mood disorders are closely linked to post-brain injury alcohol use disorders and people with both have a poorer prognosis(508).

Interestingly, several studies have shown increased rates of substance use within a year of brain injury that resolve in later years. It has been suggested that substance use may be used as an initial coping mechanism and may resolve itself as coping mechanisms improve over time(511, 514).

There is also controversy as to whether the severity of brain injury is a predictor of post-brain injury substance use. Some patients who have relapsed back into substance use following brain injury have been observed to have significantly more frequent and more severe brain injuries than those who remained abstinent(504, 508).

Substance dependent individuals with brain injury have more clinically-rated depressive symptoms and self-reported somatic symptoms and are more likely to attempt suicide(501, 507). Therefore, it is important to ensure that substance use is managed following brain injury.

Implications for management