Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician
12.1 Brain injury
Brain injury can occur as a result of head trauma or through a variety of other physiological and biochemical mechanisms:
- Head trauma can result in both open and closed head injuries.
- Acceleration/ deceleration forces on the brain can result in both macroscopic and microscopic lesions such as diffuse axonal injury.
- The brain’s response to trauma can result in local metabolic changes that seem to worsen the initial trauma-related injury.
- Other physiological or biochemical changes to the brain that cause injury include direct toxicity from substances such as alcohol and volatile solvents, hypoxia and hypoglycaemia.
- Certain personality traits or disorders (e.g. those characterised by impulsivity or violence) can result in a higher risk of brain injury.
- Brain injury may occur as a result of attempted suicide related to psychosis or depression.
- There is a strong relationship between substance use and brain injury, but the order of causality remains unclear.
- Emotional and psychiatric disturbances, especially depression, are common after brain injury among those who have a past history of brain injury.
- People who have experienced traumatic brain injury have been shown to have increased rates of suicide, suicidal ideation, suicide attempts and completed suicide.
- There is some evidence that rates of post-brain injury substance use does not actually increase over the longer term and, in fact, may even decline.