Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician
12.3 Does substance use predispose individuals to brain injury?
Substance use (including alcohol, cannabis and other illicit substances) has been associated with brain injury. Up to 40% of individuals with a brain injury have been found to meet DSM-IV criteria for substance use disorders prior to the injury. Conversely, 68% of people with a substance use disorder have also been found to have had some sort of previous head injury(503, 504).
While there is a strong relationship between substance use and brain injury, the order of causality remains unclear(504-506). Some debate also remains as to whether substance use or its severity is an actual predictor of brain injury(507, 508).
The risk of brain injury as a result of increased impulsivity and risk taking or novelty seeking behaviour associated with underlying personality traits may be exacerbated by substance use. Combined with low harm avoidance, this increased impulsivity can result in head trauma from falls or accidents or unintentional overdose(2, 501).
Substance dependence may result in attempted suicide due to the inability to cope with the negative consequences of such dependence(351, 501, 507, 509).
Brain injury can also result from:
- The direct effects of substances on the brain (e.g. frontal lobe dysfunction, cerebellar dysfunction).
- Indirect effects such as hypertension resulting in stroke.
- Secondary nutritional deficiencies such as thiamine deficiency resulting in Wernicke-Korsakoff syndrome.