<qa>  What is the purpose of a randomized controlled trial?Aim 1. Investigate the efficacy of cognitive rehabilitation in homeless returning Veterans with mental health conditions and cognitive impairment by conducting a randomized controlled trial of Compensatory Cognitive Training CCT vs. education control for 10 weeks, with a 5-week follow-up, followed by 1 year of monthly post-discharge follow-up phone calls to assess community reintegration outcomes. 