The variations in severity noted within this treatment sample and the problems associated with increasing severity of opioid dependence highlight the importance of distinguishing between more and less severely dependent individuals in a clinical setting. There are scales available to assess severity of opiate and other dependence (for instance, the Severity of Dependence Scale) [53]. The proposed substance use disorders category in DSM-V uses a symptom count to specify severity, and recent evidence suggests that although not all criteria are equal in terms of their capacity to measure severity, criteria counts are a reasonable proxy for severity [54]. Whichever approach is used, a broader conceptualization of opioid dependence which recognizes the increasing risk of other externalizing disorders as severity of opioid dependence increases makes sense from both a clinical and research perspective. In addition to a greater number of substance dependence diagnoses and personality disorders, increasing severity both across and within classes greatly increased the risk of opioid overdose, most likely due to greater opioid and other drug use [55]. Overdose is an independent risk factor for cognitive impairment which
