Info from the US, not Europe, but...
Here's one study I found that has some information:
neuro.psychiatryonline.org
More info in general:
Learn about the causes and symptoms of chronic traumatic encephalopathy, and find out how the team at the Brain Injury Research Institute is working to find a treatment.
www.protectthebrain.org
"...The symptoms of CTE can be debilitating and may have life-changing effects for both the individual and for his or her family. Some of the most common include loss of memory, difficulty controlling impulsive or erratic behavior, impaired judgment, behavioral disturbances including aggression and depression, difficult with balance, and a gradual onset of dementia...."
Young people who have sustained a head injury during their lifetime are more likely to engage in violent behavior, according to an eight-year study from the University of Michigan School of Public Health.
news.umich.edu
There are an estimated 1.7 to 3.8 million traumatic brain injuries each year in the United States, according to the CDC, of which 10 percent arise due to
www.aans.org