Bhalla IP, et al. - Researchers compared patients with diagnosed posttraumatic stress disorder (PTSD) or subsyndromal PTSD and who used a single substance at baseline vs those who used two or three and more than three different addictive substances regarding measures of PTSD symptom severity and functioning. As per observations, veterans with dual diagnoses showed increased severity of PTSD symptoms in correlation to polysubstance use, conceptualized within the multimorbidity perspective, and required complex interventions.