Our brain-imaging work at Amen Clinics shows us that mild traumatic brain injury (mTBI) is a major cause of psychiatric issues such as depression, but most people are unaware of this.

In fact, brain SPECT scans on our patients show that approximately 40% of them have experienced a prior head injury. We usually have to ask them multiple times before they remember a significant event.

I had one patient who repeatedly said he had never experienced a head injury. After being asked for the fifth time, he had one of those light-bulb moments. All of a sudden, he remembered falling out of a second-story window when he was 5 years old.

Other patients have forgotten flying through the windshield after a car accident, tumbling out of the bed of a truck, or blacking out after falling off the top bunk bed. Still, others remember a past injury but think it was too inconsequential to mention.

The majority of patients have no idea that their depression, anxiety, or lack of focus may be partly due to an incident in their past. Unfortunately, very few mental health professionals recognize this link either, because most psychiatrists never look at the brain.