Drug addiction is a serious public health problem, related to several psychiatric and psychosocial problems. Drug users are generally inserted in a context of great social vulnerability, often associated with violence, poverty, and family conflicts. The effects on the cognitive sphere of drug user patients undergoing treatment at the Center for Psychosocial Care - Alcohol and Drugs (CAPS-AD), Rio de Janeiro, Brazil, with a diagnosis of crack dependence (CUD group - Drug Use Disorder) were evaluated. Cocaine) and/or alcohol (AUD group - Alcohol Use Disorder), according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). This is a quantitative, exploratory, and descriptive research based on (sociodemographic research) and structured questionnaires (Frontal Assessment Battery, Mini-Mental State Examination, Obsessive-Compulsive Drinking Scale, Cocaine Obsessive-Compulsive Scale, Hamilton Depression Rating, Hamilton Anxiety Rating Scale). The results obtained after the application and interpretation of the questionnaires point to cognitive deterioration in drug users. At the same time, alcohol and drug users showed the worst results in the domains of attention/calculation, evocation memory and temporal/spatial orientation. The results obtained in the research showed that the users of alcohol and drugs participating in the research presented a worse result in the fields of attention/calculation, evocation memory and time/spatial orientation. This fact corroborates the hypothesis that the chronic use of alcohol and crack cocaine affects more directly prefrontal and temporal brain regions and the forebrain, areas responsible for abstract thoughts and planning, associations of thoughts and memories, attention, verbal fluency, memory visual, verbal memory, learning ability and executive functions. Manuscript profile