But “mild,” it turns out, can have consequences years later for many people. For example, in 2023 the multicenter TRACK-TBI study revealed that out of more than 1,200 people, 33 percent of those with mild TBI and 30 percent of those with moderate or severe TBI showed deterioration one to seven years after injury. Complaints can include problems sleeping, headaches, and memory and psychiatric issues. Long term, a TBI can lead to dementia, and it may also trigger several types of cardiovascular disease.