Robert E. Drake, (M.D. Ph.D.), Erica L. O’Neal, (M.D.), Michael A. Wallach, (Ph.D.)
Current intervention research on co-occurring disorders assumes the need to integrate mental health and substance abuse services at the clinical level (McHugo et al., 2006). Integrated treatment as an organizing concept arose in the 1980s when it was observed that clients with co-occurring disorders, at least those in the United States, were highly unlikely to receive treatments for both mental health and substance use problems under the existing circumstances of parallel and independent service systems (Ridgely, Osher, Goldman, & Talbott, 1987).
Instead, they would tend to be assigned to one system or the other, which would view them through its own particular lens only. Sometimes each system would try to cede these clients to the other.