Participants will be recruited for the study based on inclusion and exclusion criteria. Patients will be taken from in-patient de-addiction ward and out patient  department from Department of Psychiatry, Punjab institute of Medical Science , Jalandhar. Participants will be verbally interviewed, in which the investigator will obtain a brief socio-demographic detail of the participants, followed by  detailed history of opioid and other substance use will be obtained including the current treatment details. Criteria of Opioid use disorder will be applied based on ICD-10 (International Classification of Diseases), those fulfilling the criteria will be selected for study. Participants included in the study will be then evaluated for psychiatric morbidities as it is one of the exclusion criteria using the SCAN (Schedule for clinical Assessment in Neuropsychiatry ), this will be applied by the investigator. They will be undergoing IQ assessment done by Clinical Psychologist using Ravens Progressive Matrices. Participants scoring below 90 will be excluded from the study.

Participants current stage in Opioid use disorder will be assessed with help of Clinical Opioid withdrawal scale (COWS) by the investigator.  Those scoring less than 5 will be included in the study.

Then the self-administered computer based testing of cognition will be done  using CANTAB , where the participant will be supervised by the investigator in case they have difficulty in conducting the test. Following this the scores obtained on the scales will be noted using Microsoft excel sheet and will be statistically  analyzed. Comparison based on socio-demographic and clinical parameters like dose of opioid use, duration of Opioid use will be done and results will be analyzed using appropriate statistical tests.