This prospective cohort study aims to investigate factors associated with psychiatric symptom severity in participants diagnosed with methamphetamine-induced psychotic disorder (MP) with and without lifetime cannabis use (LCU). Participants hospitalized at Elazığ Mental Health and Diseases Hospital who meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) criteria for MP will be included.

Participants will be divided into two groups based on the presence or absence of LCU. Psychiatric symptoms and clinical characteristics will be assessed weekly during an eight-week inpatient follow-up period using standardized psychometric instruments.

The study aims to determine whether LCU influences the course and severity of psychiatric symptoms in MP and to identify environmental, individual, and familial factors associated with symptom progression.

Methamphetamine is a synthetic central nervous system stimulant with strong addictive potential and significant neurotoxic effects. Chronic methamphetamine exposure causes dopaminergic dysregulation and may lead to the development of psychotic symptoms, including hallucinations, delusions, and behavioral disturbances. Methamphetamine-induced psychotic disorder (MP) occurs in a substantial proportion of individuals who use methamphetamine.

Cannabis use is frequently observed among individuals who use methamphetamine. Lifetime cannabis use (LCU) has been associated with a variety of psychiatric symptoms including anxiety, irritability, sleep disturbances, cognitive impairment, and psychotic symptoms. However, the effect of LCU on the course of MP has not been clearly established.

Most existing studies examining psychotic symptoms in MP have been cross-sectional or retrospective in design. Prospective cohort studies investigating symptom progression and associated risk factors remain limited.

This study is designed as a prospective cohort study and will conduct in participants hospitalized at Elazığ Mental Health and Diseases Hospital psychiatry inpatient clinic. Participants diagnosed with MP according to (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) DSM-5-TR criteria will be included and divided into two groups: Group 1=Participants with MP plus LCU (MP+LCU), Group 2=Participants with MP (no current and lifetime cannabis use).

LCU will be defined as using cannabis three or more times within the past 30 days and/or using cannabis more than forty times during the past year.

Participants will be followed weekly for eight weeks during hospitalization. Psychiatric symptoms, substance/drug use characteristics, and psychosocial variables will be assessed using standardized psychometric instruments.

The scales used/will be used in this study are as follows: Insight Assessment Scale, Addiction Profile Index Clinical-Practitioner Form, Positive and Negative Syndrome Scale, Global Assessment Scale, Pittsburgh Sleep Quality Index.

The primary aim of this study is to identify environmental, familial, and individual factors associated with psychiatric symptom severity in participants with MP and to determine whether LCU affects symptom progression.

After completion of the follow-up period, the data will be analyzed using a statistical software and the results will be prepared for publication in scientific journals.

1. For Methamphetamine-Induced Psychotic Disorder plus Lifetime Cannabis Use (MP + LCU) Group:

   *Inclusion Criteria:

   • Diagnosis of MP according to DSM-5-TR

   • Diagnosis of Cannabis Use Disorder according to DSM-5-TR
   • Medication-free for at least one month prior to admission
   • Age ≥ 18 years and <65 years
   • Provided informed consent

   For Methamphetamine-Induced Psychotic Disorder plus Lifetime Cannabis Use (MP + LCU) Group:

   *Exclusion Criteria:

   • Hypertension

   • Diabetes mellitus

   • Chronic kidney disease

   • Rheumatoid arthritis

   • Systemic lupus erythematosus

   • Cardiac illness

   • Severe neurological disorders
   • Immunological or systemic illness
   • Primary psychiatric disorders other than MP
   • Alcohol use disorder

2. For Methamphetamine-Induced Psychotic Disorder (MP without LCU) Group:

   *Inclusion Criteria:

   • Diagnosis of MP according to DSM-5-TR

   • Medication-free for at least one month prior to admission

   • Age ≥ 18 years and <65 years

   • Provided informed consent

   For Methamphetamine-Induced Psychotic Disorder (MP without LCU) Group:

   *Exclusion Criteria:

   • Hypertension

   • Diabetes mellitus

   • Chronic kidney disease

   • Rheumatoid arthritis
   • Systemic lupus erythematosus
   • Cardiac illness
   • Severe neurological disorders
   • Immunological or systemic illness
   • Primary psychiatric disorders other than MP
   • Alcohol use disorder

The study population will consist of adult male participants aged 18-65 years who were admitted to Elazığ Mental Health and Diseases Hospital.

The methamphetamine-induced psychotic disorder (MP) with and without lifetime cannabis use (LCU) group will include consecutive participants diagnosed with MP with and without LCU according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR).

Both groups will consist of active methamphetamine users and will be hospitalized for clinical management at the time of assessment. Urine toxicology screening was performed at admission to confirm substance/drug use status.

Deidentified individual participant data (IPD) underlying the results reported in this study [including sociodemographic variables, Insight Assessment Scale, Addiction Profile Index Clinical-Practitioner Form, Positive and Negative Syndrome Scale, Global Assessment Scale, Pittsburgh Sleep Quality Index] will be made available to qualified researchers upon reasonable request for academic purposes.

Data will be shared after removal of all direct identifiers and in accordance with applicable ethical approvals and data protection regulations. Access to the data will require a methodologically sound research proposal and a data use agreement. Requests should be directed to the corresponding author.

Data will be available beginning 6 months after publication and will remain available for 5 years.

Access will be granted to researchers who provide a methodologically sound proposal. Requests must be approved by the principal investigator and may require a data use agreement in accordance with institutional and ethical regulations.