I've worked with homeless people in a shelter environment before, and my experience was that the most prevalent psychiatric issues among that population were sc

I've worked with homeless people in a shelter environment before, and my experience was that the most prevalent psychiatric issues among that population were schizophrenia, bipolar disease, and various addictions (especially alcoholism). There were a few who I thought had some ADHD issues, but I don't know if that led directly to them becoming homeless or not. Granted this does not constitute anything like a research study, but it does suggest that just treating people for ADHD might not have a lot of impact. I did a quick search and was only able to come up with the abstract for a study that claimed ADHD had a ~4-5x higher prevalence among homeless individuals than non-homeless individuals. The abstract alone indicates a couple potential issues with the study (e.g. subjects were only white men, and they used a population sourced from people who had gotten treatment at a particular medical center), and it doesn't indicate any causation. I don't really think ADHD meds are regulated to keep people homeless, and I'm not sure about the meth epidemic being related to ADHD, but I don't think it would hurt to get people the treatment they need, whether they can pay for it or not.