Getting clean and sober is challenging enough, but recently it’s been documented that a sizable percentage of people with substance abuse issues are also suffering in addition from a mental illness. This dual diagnosis represents as many as 40 percent of those with substance abuse issues, according to a recent study by the Substance Abuse and Mental Health Services Administration (SAMHSA). That makes treatment somewhat more challenging since the person and the therapist need to deal with the underlying mental health issue as well as the substance abuse.