Add-on MEmaNtine to Dopamine Modulation to Improve Negative Symptoms at First Psychosis

Inclusion Criteria: * Patients: * Antipsychotic-free(as defined under Exclusion Criteria below), first episode psychosis * Fulfilling the diagnostic criteria of schizophrenia, persistent delusional disorder, acute and transient psychotic disorders, schizoaffective disorder, other non-organic psychotic disorders and unspecified non-organic disorders (ICD-10: F20.x; F22.x; F23.x; F24.x; F25.x; F28; F29); verified by PSE interview. * Age: 18-45 years * Legally competent (In Danish: 'myndige og habile i retslig forstand') Healthy controls: * No first-degree relative with known major psychiatric disorder (ICD-10: F1x; F2x; F3x) * Age 18-45 years * Legally competent (In Danish: 'myndige og habile i retslig forstand') Exclusion Criteria: * Patients * Prior use of antipsychotic medication longer than an episode of two weeks in the previous year and/or 6 weeks lifetime, and/or antipsychotic treatment within 30 days prior to inclusion. * Treatment with antidepressant medication the last 7 days * Current substance dependence ICD-10 (F1x.2) or substance abuse in any period up to 3 months prior to referral (exception: tobacco/nicotine, F17.2) * Head injury with more than 5 minutes of unconsciousness, lifetime * Any coercive measure * Metal implanted by operation * Head or neck tattoos * Pacemaker * Pregnancy (assessed by urine HCG) * Female patients: Unwillingness to use safe contraception (Intra Uterine Device/System or hormonal contraceptives) during the study period. * Severe physical illness * Allergies to any of the ingredients in the aripiprazole tablets or memantine tablets Healthy controls: * Lifetime substance abuse/dependence ICD-10 (F1x.1/F1x.2) (exception: tobacco/nicotine, F17.1/F17.2) * Lifetime treatment with antidepressants * Head injury with more than 5 minutes of unconsciousness * Metal implanted by operation * Head or neck tattoos * Pacemaker * Pregnancy (assessed by urine HCG) * Severe physical illness