https://www.entrepreneur.com/article/375202

More than 2 million people sustain traumatic brain injuries (TBI) every year. Professional athletes, military veterans, first responders and many others suffer severe anxiety and depression and other debilitating symptoms as a result. Many more report symptoms of chronic traumatic encephalopathy (CTE), which is the result of a series of head injuries, such as recurrent concussions, sustained over months or years.

Both of these types of injuries have long been known to be associated with symptoms of post-traumatic stress disorder (PTSD) and depression. But research reveals that physical brain injuries may actually cause PTSD and depression, yet remain undetected and untreated.