Traumatic brain injury is considered to be a risk factor for psychotic disorder, which includes symptoms such as delusions and hallucinations. A recent review of psychotic disorders due to traumatic brain injury found the following:
1. Psychotic disorders can develop after a mild, moderate, or severe traumatic brain injury, however, most cases were reported when the person had suffered a loss of consciousness.
2. 38% of people with a traumatic brain injury developed a psychotic disorder in the first year after injury, and 36% developed a psychotic disorder after five years, suggesting that there is a bimodal distribution of time. People will either develop the disorder in the first year or after 4-5 years.
3. Seizure disorders are more common in people who develop psychotic disorder after a brain injury (24%) than people who don't (7%).
4. Males and people with a family history of schizophrenia are at greater risk of developing psychotic disorder after brain injury.
5. Persecutory delusions and auditory hallucinations are the two most common symptoms of psychotic disorder after brain injury.
6. People who develop psychotic disorder after brain injury are more likely to have lesions in the frontal and temporal lobes, unlike people who have schizophrenia, who are most likely to have enlarged ventricles.
These findings suggest that psychotic disorder that is associated with a brain injury needs to be considered a neurobiological, rather than a psychiatric, syndrome.
Fujii D and Fujii DC. Psychotic disorder due to traumatic brain injury: Analysis of case studies in the literature. The Journal of Neuropsychiatry and Clinical Neurosciences. (July 2012).