Inclusion Criteria:  Subjects aged between 18 and 55 years (from both sexes [or genders]); Diagnosed with CUD (moderate or severe) according to the Structured Clinical Interview for DSM-IV (SCID) (mode of cannabis consumption can be inhalation or ingestion); Diagnosis of current (past 30 days) PTSD, using the CAPS-5 on screening; On antidepressant medication(s) for at least 1 month (to ensure safety and homogeneity as PTSD treatment of our population); Be able to provide written informed consent; and Be able to communicate in English.  Exclusion Criteria:  diagnosed with a severe or unstable medical illness that precludes safe participation in the study as per the study physician; diagnosed with schizophrenia, schizoaffective disorder, or bipolar disorder or current acute psychosis or mania based on DSM-5 criteria; current suicidality risk as indicated by the Columbia Suicide Severity Rating Scale (C-SSRS) with concurrence after the study physician's evaluation if the response to C-SSRS questions 1 or 2 is "yes" 34; and have pain interfering with normal function as reported by the 12-Item Short Form Survey (SF-12) (moderate or higher interference).