CLUMP is a project of translational research that intends to bridge the gap between what we already know about pharmacogenetics of antipsychotic drugs and what we still do to treat patients with first-episode psychosis (FEP). We aim to improve the adherence to antipsychotic drugs and, therefore, the outcomes of patients with FEP. To achieve this aim, our objectives are to: (1) Introduce a pioneering early intervention model of Personalised Precision Psychiatry, including pharmacogenetics, for patients with FEP; (2) ascertain whether such a model can reduce the elevated discontinuation rates of antipsychotic medications in this group; (3) assess the impact of this model on pragmatic efficacy and functional measures; (4) determine whether this innovation can bring cost benefit; and (5) establish a blueprint for implementing this precision model nationally and internationally. We shall compare all-cause discontinuation rates of the first prescribed antipsychotic medication (primary outcome), discontinuation rates by causes, pragmatic efficacy and tolerability measures, functional outcomes, and healthcare costs between two cohorts of patients with FEP followed for one year. One cohort will be comprised of patients treated before the implementation of the early intervention model of Personalised Precision Psychiatry, and the other of new patients treated under this model. Also, we shall compare pharmacogenetic information, and its implications for clinical management, between these patients and another national cohort of patients with either longer-term psychotic disorders or other mental health problems.

Inclusion Criteria

• Patients with a diagnosis of first-episode psychosis, either non-affective or affective.
• Patients aged 12-35 years.
• Patients followed by clinical services for at least one year, or earlier if there was evidence of antipsychotic treatment discontinuation.
• For cohort one: Patients and/or their family or legal representatives must provide written consent to take part in the CLUMP Project, including pharmacogenetics analysis.
• For cohort two: This will not be a mandatory inclusion criterion, but all patients will be approached by our research team seeking their consent to obtain their pharmacogenetic profile for research purposes.

Exclusion Criteria

• Patients with first-episode psychosis due to organic causes, for example, brain diseases such as Huntington's and Parkinson's disease, HIV, syphilis, dementia, brain tumours or cysts, or brain injury.
• Patients with moderate to severe intellectual disability.
• Patients who plan to reside (cohort one) or spent (cohort two) most of the one-year follow-up period in a locality outside of the PRINT's catchment area.

Cohort one: A prospective sample of patients with a first episode psychosis referred over 18 months to the new early intervention in psychosis programme of Personalised Precision Psychiatry called PRINT - PRevention and early INTervention in mental health - at Salamanca University Healthcare Complex (CAUSA) in Salamanca, Spain.

Cohort two: A retrospective, consecutive (in reverse chronological order as registered in CAUSA electronic health records) sample of patients who suffered a first-episode psychosis before the implementation of PRINT.

Cohort three: For additional comparative purposes, we shall analyse environmental, clinical and pharmacogenetic information of patients with psychotic disorders of more than five years of evolution or with other mental disorders, whose data are currently stored, and ethically approved for research use, in our Unit of Pharmacogenetics and Precision Medicine at CAUSA.