Traumatic brain injury linked to schizophrenia
Traumatic brain injury can have serious and long-lasting consequences, such as memory loss, motor coordination problems, and depression. Now a new study suggests that it can also make it more likely to trigger schizophrenia, a mental health disorder characterized by impairments in judgment, thinking and perception.
The results show people who have suffered from a traumatic brain injury (TBI) are 1.6 times more likely to develop schizophrenia compared with those who have not suffered such an injury. The risk was shown to be particularly elevated for those with a family history of the disorder, which may have made them innately susceptible.
Previous studies regarding TBI and schizophrenia have generated mixed results as to whether the conditions are linked. This new study is one of the first to pool information from past research in a systematic way to get an indication of the risk.
It is important to keep in mind that the study demonstrates that a link exists, not necessarily that TBI causes the disorder. For example, it could be that patients were already developing the psychiatric condition when their injury occurred, the researchers said. More work needs to be done to find exactly what's behind this relationship, they said.
Traumatic brain injury results from a serious jolt or blow to the head that may or may not penetrate the skull. It can result in a concussion, loss of consciousness and even profound amnesia in some of the more severe cases. TBI is known to increase the risk of some psychiatric disorders, including anxiety disorders, substance use disorders and personality change, the researchers said.
Mary Cannon, of the Royal College of Surgeons in Dublin, and colleagues analyzed nine previous studies that included participants who had suffered TBI and participants from the general population that had not suffered TBI.
Overall, TBI was associated with an increased risk of schizophrenia, the researchers found. People who suffered TBI and also had a relative with schizophrenia were 2.8 times more likely to develop the psychiatric condition than those who hadn't had TBI, the study said.
Schizophrenia affects about 1.5 percent of the population worldwide. It is a mental disorder characterized by the disintegration of thought processes and emotional responsiveness. It most commonly manifests as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social or occupational dysfunction.
Interestingly, the risk of schizophrenia did not increase in more severe brain injuries, the study showed. That may mean other factors, such as the location of the trauma, matter more in terms of schizophrenia risk, the researcher said. The study did not take into account the location of the TBI.
The study did not conduct any new trials or fresh research; rather, it relied on surveys of past studies. Thus, the study is only as good as the data the researchers chose to review, said Dr. Dolores Malaspina, a professor of psychiatry and environmental medicine at New York University. But the studies included in the new analysis are "excellent," Malaspina said.
Malaspina said brain injury can pull on and break neural connections, which can have real, biological consequences. Depression and personality changes are common repercussions of TBI. And there are some cases in which a patient has developed schizophrenia due in part to their TBI, Malaspina said.
Some individuals may be genetically predisposed towards schizophrenia and all it takes is a trigger, such as TBI, to set off their symptoms. "Exposure to a brain injury in those people can unmask a psychotic illness," or bring one forward that would have otherwise been compensated, Malaspina said.
The study was published Aug. 2 in the journal Schizophrenia Bulletin.