Effectiveness of tDCS on Reducing Craving in Patients Practicing Chemsex: a Single-center, Double-blind, Randomized Controlled Pilot Trial

Inclusion Criteria: * Patient who provides written consent * Patient aged ≥ 18 years * Patient motivated and willing to change chemsex behavior, assessed by examiner during screening and inclusion visits * Patient using at least one of the following psychoactive substances to modify sexual performance and/or experience: * Cathinones, or methamphetamine, or MDMA, or cocaine, or ketamine, or GBL/GHB * ≥ 1 time per month over the past 6 months and/or ≥ 10 times over the past year Exclusion Criteria: * Patient with a substance use disorder not involved in the practice of chemsex * Patient with a recent change (\< 1 month) in the prescription of a psychotropic treatment * Patient presenting an acute psychiatric condition requiring hospitalization and/or immediate modification of a psychotropic treatment * Patients with unstable or uncontrolled neuropsychiatric disease * Patients with a history of epileptic seizures * Patients with unexplained episodes of loss of consciousness, as this condition may be linked to cerebral alterations or epilepsy * Patients with advanced or decompensated somatic pathology, requiring hospitalization expected during study follow-up * Patients suffering from any serious life-threatening illness, such as congestive heart failure, chronic obstructive pulmonary disease or active neoplasia * Patients with implanted cerebral medical devices, implanted pacemakers, or any electrically, magnetically or mechanically activated implant. * Patients with cardiac, neural or drug implants * Patients with vascular clips or other electrically sensitive support systems in the brain * Patients with severe brain lesions * Patients with skin lesions at stimulation sites * Patients with skin problems such as dermatitis, psoriasis or eczema * Patients with severe or frequent headaches * Patients who have already benefited from tDCS sessions * Pregnant, parturient or breast-feeding women (pregnancy test) * Staff working in the addictology department of Dijon University Hospital * Patient participating in another clinical trial * Patient not affiliated to national health insurance * Patient unable to complete assessment scales * Patient under psychiatric care without consent or under legal protection (guardianship, curatorship) * Major incapable or unable to provide consent