Substance abuse treatment and psychiatric comorbidity: do benefits spill over?

This study looked at homeless cocaine addicts with an independent mental illness. They recieved addiction treatment but no psychiatric treatment:

There was a 32% reduction in the prevalence of comorbid nonaddiction psychiatric disorder from baseline to 6 months, with similar reductions in the prevalence of mood (-32%) and anxiety-related disorders (-20%) (p=0.12).