Chapter List Guidelines In a NutshellAbout these guidelinesPart A: What is comorbidity and why is it important?A1: What is comorbidity?A2: How common is comorbidity and why is it of concern?How common are mental health disordersHow common is comorbidity among clients of AOD treatment services?What are the harms associated with comorbidity?What is the impact of comorbidity on treatment outcomes?A3: Guiding principles of working with clients with comorbidityA4: Classification of disordersPart B: Responding to comorbidityPart C: Specific population groupsAppendicesAbbreviationsGlossaryReferences Download PDF How common is comorbidity and why is it of concern? Download page Key Points Mental health disorders are common among clients of AOD services. The most common comorbid mental health disorders are anxiety, depression, PTSD, and personality disorders. In addition to those with mental health disorders, there are a number of people who present to AOD treatment who display symptoms of disorders while not meeting criteria for a diagnosis of a disorder. Although people with comorbid mental health conditions may have more complex profiles, they have been found to benefit as much from traditional AOD treatment methods as those without comorbid mental health conditions. How common are mental health disordersHow common is comorbidity among clients of AOD treatment services?What are the harms associated with comorbidity?What is the impact of comorbidity on treatment outcomes?