According to the National Alliance to End Homelessness’s 2015 report, in January 2014, there were 578,424 people sleeping either outside, in emergency shelter, or at a transitional housing program. Over the course of the entire year, it’s estimated that 3.5 million people will experience homelessness at some time in the United States. While this number is high for one of the most advanced countries in the world, a solution to the root cause of the problem may be closer than we think: better recognition and treatment for those with brain injuries.

House the Homeless Inc. in Austin, Texas found in their 2010 survey that 49% of the people who were experiencing homelessness were so disabled that they were unable to work a full time job. Disablement can come in a variety of forms, but one of the highest correlations can be seen in relation to brain injuries. A different study done in 2014 at St. Michael’s hospital in Toronto found a number of links between traumatic brain injury and homelessness. For example, nearly half (45%) of the 111 men who participated in the study had a positive screening result for a traumatic brain injury and 87% reported a first injury before the onset of their homelessness.

The study also found that a positive TBI screening result was significantly associated with other issues that lead to homelessness such as a lifetime history of mental illness or arrest as well as a parental history of substance abuse. This correlation is especially troubling since many of the injuries from the positive screening results, aside from instances of assault (66%), were sustained by at least one incident that can occur under regular circumstances such as during sport or recreation (44%), motor vehicle collisions (42%), and by fall (42%).

Earlier this month, House the Homeless in Austin released another installment with their 2016 survey, which dug deeper into the relationship between traumatic brain injury and people experiencing homelessness. Although the sample size is small at 248 people within the Austin area, the results are telling. For example, 80% of homeless respondents said they had been hit hard enough in the head to see stars, which is indicative of a concussion. Of those who saw stars, 80% said that the incident left them confused and 56% said that it caused them to suffer recurring headaches. Furthermore, while only 10% of concussions are generally associated with being knocked out, between the 228 who answered that question, there were 109 knock outs reported, meaning that a large number of concussions are either not recognized or not reported.

Although homelessness is due to a mixture of complex factors, it’s hard to argue with the high correlation seen here across multiple studies. Especially since better treatment has reduced homelessness among veterans since 2009, attention specifically to brain injury and mental health has proven that it can have a positive impact on keeping people off the street. Nevertheless, solving all of the exact causes for homelessness will require some serious effort, but beginning with the brain is a great start.