An unanswered question, say experts, is whether the brain injury causes the homelessness or if it is the other way round. “The relationship between homelessness and TBI could function both ways – TBI could increase the risk of homelessness, and homelessness could increase the risk of TBI,” said Jehannine Austin from the British Columbia mental health and substance use services research institute in Canada, where the study was carried out.
Some interesting research here on the link between homelessness and traumatic brain injury:
https://www.theguardian.com/society/2019/dec/02/half-of-all-homeless-people-may-have-had-traumatic-brain-injury