A traumatic brain injury sustained in childhood or early teenage years could predispose someone to homelessness as an adult.
Dr. Topolovec-Vranic looked at data on 111 homeless men aged 27 to 81 years old who were recruited from a downtown Toronto men's shelter. She found that 45 per cent of these men had experienced a traumatic brain injury, and of these, 70 per cent were injured during childhood or teenage years and 87 per cent experienced an injury before becoming homeless. [emphasis mine]
from that source
The study found that players who headed the ball in the last 12 months more than about 1,100 times showed significant signs of structural damage in their brains. The sites affected were in brain areas associated with attention, memory and the processing of visual information. Players who headed the ball less than 1000 times a year showed no signs of brain damage.
The type and location of white matter loss was shown to resemble that shown by people who had traumatic brain injuries such as a serious concussion.