If you’ve ever gotten a concussion before—maybe during sports or even a car crash—you know it can be an incredibly disorienting experience. You might be dazed, feel nauseous, and even lose your memory temporarily. Luckily, there’s a good chance you’ll recover in just a few days or weeks. However, a significant amount of people don’t—suffering from long-lasting and unseen symptoms for the rest of their lives.
One of these issues is depression. Studies have shown that incidence of the symptom emerges in half of patients within a year of a traumatic brain injury (TBI). Nearly 66 percent show signs of depression within seven years following the injury.
This can be for a variety of reasons, such as an emotional response to the trauma of a brain injury, or a patient’s genetic predisposition to depression. However, a new study suggests that the issue could be much deeper than that.
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A paper published Wednesday by an international team of researchers in the journal Science Translational Medicine found that the brain circuits involved in depression differed between patients with TBI and those without it. The findings suggest that depression caused by brain injury may be a different kind of mental disorder altogether than what follows from other causes such as genetics or PTSD.
This could lead to better, more targeted treatments for those suffering from TBI.
“Many clinicians have suspected that this is a clinically distinct disorder with a unique pattern of symptoms and unique treatment response, including poor response to conventional antidepressants,” Shan Siddiqi, an assistant professor of psychiatry at Harvard Medical School and co-author of the paper, said in a statement. “But until now, we didn’t have clear physiological evidence to prove this.”
The study involved 273 adult patients with TBI from a variety of causes including car accidents and sports related injuries. The participants were given an MRI that analyzed 200,000 points of their brains at roughly 1,000 different times. This resulted in 200 million data points per patient. The results were then compared with data from a group that did not have TBI, a group that did not have depression, a group with depression but with no TBI, and a group with PTSD.
The authors found that, while the location of the brain circuit that causes depression were the same between the TBI depression group and the non-TBI depression group, connectivity with this circuit was increased with those who suffered from an injury. The difference was so distinct that the researchers even proposed a new name for the malady: TBI affective syndrome.
“Our findings help explain how the physical trauma to specific brain circuits can lead to development of depression,” Siddiqi explained. “If we’re right, it means that we should be treating depression after TBI like a distinct disease.”
The authors are already using this method of brain mapping in order to help personalize new treatments for patients. These treatments include the use of transcranial magnetic stimulation, which is essentially zapping the brain with large magnets. This process has been shown to greatly improve depressive symptoms in past research.
Siddiqui and one of his co-authors even used the method to treat 15 patients in a pilot trial—and saw great success with the treatment. They now hope to build off of this process and replicate the study in a multicenter military trial.
“I've always suspected it isn't the same as regular major depressive disorder or other mental health conditions that are not related to traumatic brain injury,” co-author David Brody, a neurologist at Uniformed Services University in Bethesda, Maryland, said in a statement. “There's still a lot we don't understand, but we're starting to make progress.”
