Cannabis and Methamphetamine Use Patterns in a Psychiatric Inpatient Setting in Iran

Substance use has a considerable prevalence worldwide, with approximately 284 million people reporting having used drugs at least once (1). It is estimated that cannabis has been used at least once in the past year by 209 million people, making it the most commonly used drug worldwide, followed by opioids (61 million) and amphetamines (34 million). The prevalence of cannabis and amphetamine use has increased globally in recent years, with a considerable increase in the number of disability-adjusted life years (DALYs), particularly among younger age groups (1, 2).

The increasing prevalence of cannabis use is closely linked to psychiatric disorders, which are significant concerns. Cannabis use increases the risk of developing psychiatric conditions, including but not limited to anxiety disorders, depressive disorders, and psychosis (3, 4). Additionally, cannabis use contributes to the worsening of symptoms and the progression of existing psychiatric disorders (5, 6). Conversely, individuals with psychiatric disorders may also be more susceptible to using cannabis as a form of self-medication or a coping mechanism (7).

The interplay between the use of methamphetamine and psychiatric disorders also demands significant attention. Methamphetamine use plays a substantial role in increasing the risk of experiencing psychotic symptoms, exhibiting a dose-response correlation. Methamphetamine use is also strongly associated with drug-induced psychotic disorders (8). On the other hand, psychiatric patients may be more inclined to resort to stimulants such as methamphetamine to experience psychotropic effects that alleviate their current symptoms (9).

Considering the current trend in stimulant and cannabis use (2), along with evidence showing their strong relationship with psychiatric disorders, it is crucial to investigate patterns of use among psychiatric patient populations. This paper is part of a larger study on cannabis use and cannabis-induced mental disorders among hospitalized psychiatric patients in Iran. In this paper, we aimed to investigate the rate and patterns of lifetime and recent illicit drug use and its related characteristics in a sample of patients in a psychiatric hospital in Tehran, Iran, with a focus on cannabis and methamphetamine. We also compared the demographic and clinical characteristics of psychiatric inpatients with and without cannabis or methamphetamine use during the three months before hospitalization. Furthermore, via standard questionnaires, we aimed to investigate drug use-related risks among participants with recent cannabis or methamphetamine use, as well as their subjective experiences of cannabis intoxication and withdrawal among those with recent cannabis use.

Among a total of 300 patients (median age: 35.0 years, IQR: 17; 65.3% male), the most prevalent reason for referral to the psychiatric ward was aggression (49.7%), followed by suicide attempts (31.0%) and acute psychosis (16.7%). Recent use of any type of substance was reported by 38.0% of the participants, with 19.3% and 19.0% reporting recent use of alcohol and opioids, respectively. Among the total cases, 11.7% reported CU in the past three months, and 15.0% reported MU during the same period. Lifetime use of substances was reported by 49.0% of the patients, with opioids being the most commonly used group of substances (35.0%), followed by stimulants (26.7%), alcohol (23.7%), and cannabis (20.3%). Additionally, opioid use disorder was the most commonly diagnosed substance use disorder (SUD) in our sample, second to polysubstance use disorder.

Positive urine tests were detected for morphine in 16.7% of the cases (28.6% of those with recent CU and 40.0% of those with recent MU), methamphetamine in 12.7% (31.4% of those with recent CU and 71.1% of those with recent MU), and tetrahydrocannabinol (THC) in 6.0% (45.7% of those with recent CU and 15.6% of those with recent MU). We found discrepancies between self-reported drug use and urine toxicology results. Among participants who self-reported drug use, 28 tested positive for opioids, 30 for methamphetamine, and 16 for cannabis. However, a significant number of participants who denied using these substances also tested positive: 19 for opioids, 8 for methamphetamine, and 4 for cannabis. Conversely, some participants who reported drug use tested negative: 24 for opioids, 2 for methamphetamine, and 6 for cannabis.

Patients with recent CU were more likely to be male, unemployed, and significantly younger than those without recent CU. Similar patterns were also found in the group with recent MU compared with those without recent MU, except that the age distributions of patients with or without recent MU did not differ. Those with recent MU and CU were more likely to have been referred due to aggression and were also more likely to report recent and lifetime use of other illicit substances, including alcohol, opioids, and stimulants, as well as current tobacco and opioid use, than were patients without recent CU or MU. Recent cannabis users also reported significantly higher rates of recent alcohol use than did those without recent CU.

Among the total participants, recent cannabis users and recent methamphetamine users (23.3%, 62.9%, and 82.2%, respectively) were diagnosed with SUDs, and both recent cannabis and methamphetamine users were significantly more likely to be diagnosed with polysubstance use disorder. In addition to SUDs, the most common diagnosis at discharge was bipolar mood disorder among all patients and those with recent CU, and psychotic/mood disorders due to substance use in the group with recent MU. Recent cannabis users’ distribution of psychiatric disorder diagnoses, such as psychotic or mood disorders due to substance use, did not significantly differ from that of patients without recent CU, except for a higher rate of bipolar disorder diagnosis. On the other hand, those with recent MU had significantly higher rates of psychotic/mood disorders due to substance use diagnoses than did those with no recent MU.

The median duration of hospitalization was 27.0 days (IQR: 22) among all participants, and there was no significant difference in hospitalization duration between participants with and without recent CU or between those with and without recent MU. Details regarding patient characteristics and substance use are presented in Table 1.

World Health Organization’s alcohol, smoking, and substance involvement screening test data were obtained from participants who reported CU or MU during the past three months and those who had a positive urine toxicology test for methamphetamine or cannabis. While half of the recent cannabis users (50.0%) reported using cannabis on a weekly basis, most of the recent methamphetamine users (69.8%) reported using methamphetamine daily or almost daily. Both groups reported a strong desire to use the substance, with 88.2% of the subgroup with recent CU and 100.0% of the subgroup with recent MU expressing this desire. Those with recent MU were also more likely to fall into the high-risk category than those with recent CU (53.5% versus 23.5%). Higher rates of substance use-related health, social, legal, and financial risks were reported by recent methamphetamine users compared to those with recent CU. Details regarding the WHO-ASSIST findings are presented in Table 2.

In this study, we investigated the rates and patterns of lifetime and recent substance use, particularly cannabis and methamphetamine, in a sample of psychiatric inpatients in Iran. Our findings revealed that 38.0% of our cases reported recent use of at least one type of substance, whereas one-fifth, one-seventh, and one-ninth of the total cases reported opioid use, methamphetamine use, and CU, respectively, in the past three months. This finding is consistent with a recent study on Iranian psychiatric inpatients, which reported that 37.9% of the participants reported recent substance use (13). Similarly, in another study, 36.7% of psychiatric inpatients reported recent use of illicit substances of any type (14).

The prevalence of recent CU in our sample was notably higher than rates reported in prior studies of psychiatric inpatients. For instance, a 2013 study in Iran found a current CU rate of 2.8% (14), whereas we found a significantly higher rate of 11.7% for recent CU. While this difference could be attributed to potential underdiagnosis in the previous study, the observed increase in rates is concerning. Approximately one-fifth of our patients disclosed a history of lifetime CU. Compared with data from meta-analyses of worldwide studies among psychiatric groups, the prevalence of lifetime CU is 30% among patients with bipolar disorder (15), 11.7% among those diagnosed with major depressive disorder (16), and 26.2% among patients with schizophrenia spectrum disorders (17), suggesting variability across diagnoses.

We also found elevated MU, with 15% and 26% of the patients reporting recent and lifetime MU, respectively. Those suffering from psychiatric conditions have greater odds of MU (18). Similarly, in a study conducted in 2013 among an Iranian psychiatric inpatient population, the prevalence of MU was reported to be 3.3% (14). Findings derived from meta-analyses of global studies involving psychiatric populations demonstrate that the prevalence of stimulant use in the past 12 months and lifetime is 7.2% and 8.9%, respectively, among patients with psychosis (19). Conversely, the estimated prevalence of recent or lifetime stimulant use is 4.8% among individuals with major depressive disorder (16) and 7.3% among patients with schizophrenia spectrum disorders (17).

We found that approximately 40% of the patients had a history of recent substance use. Alcohol was the most commonly used substance, followed by opioids, which accounted for half of the individuals with recent substance use. Moreover, the majority of our participants diagnosed with SUDs were diagnosed with polysubstance use disorder, followed by opioid use disorder. Studies conducted in different regions of Iran have consistently shown that opioids, mainly opium, are the most commonly used illicit substances in psychiatric inpatient settings (20). Opioids are the main drugs used in Iran, suggesting a similar pattern of drug preference. This pattern is in accordance with the prominent drug production and transit locations in the region, as well as with cultural factors (1, 21).

In our study, the rate of positive urine tests for morphine, methamphetamine, and cannabis was 16.7%, 12.7%, and 6.0%, respectively. These findings can be compared to a similar study conducted in Iran on patients referred to the emergency psychiatric room, where the positive urine toxicology rates for morphine, methamphetamine, and cannabis were 27.4%, 14.5%, and 3.5%, respectively (22). The differences in these rates could be attributed to the different settings and patient populations.

The discrepancies between self-reported drug use and urine toxicology results highlight potential limitations in relying solely on self-reports for assessing substance use. The presence of opioids, methamphetamine, and cannabis in participants who denied using these substances suggests underreporting, which may stem from social desirability bias, fear of legal or social consequences, or lack of awareness of drug consumption (e.g., through prescription medications or contaminated substances). On the other hand, the negative test results among participants who reported drug use could indicate variability in detection windows, differences in drug metabolism, or potential errors in self-reporting.

In our study, the MU and CU groups were more likely to be referred for aggression. Patients with SUD, particularly those using cannabis and methamphetamine, had an increased likelihood of violence-related admissions compared with those without SUD (23). Neuroimaging studies on cannabis (24) and methamphetamine (25) users revealed impairments in the prefrontal cortex, affecting inhibitory processing. These neural deficits limit the ability to suppress impulsive tendencies, which are significant factors in aggressive behaviors. Overall, our findings contribute to the growing evidence highlighting the association between substance use and aggression in psychiatric inpatients.

Participants with recent MU were more likely to be diagnosed with psychotic/mood disorders due to a substance use diagnosis and were less likely to be diagnosed with primary psychotic or mood disorders. MU has been linked to various psychiatric symptoms and disorders, including symptoms of psychosis, anxiety, and depression (26, 27). Patients with MU are vulnerable to methamphetamine-induced mental disorders, which can be challenging to distinguish from primary mental disorders (28). However, it is crucial to differentiate between the two in clinical practice since the treatment planning and management strategies for these conditions may differ (28, 29).

We did not find a significant relationship between recent CU and psychotic or mood disorders due to a substance use diagnosis, which may be attributed to the small sample of recent cannabis users in our study. However, the relationship between heavy CU and psychotic disorders has been demonstrated in previous research (30, 31). Additionally, previous findings have linked CU to bipolar disorder (6, 31), which is compatible with the relationship observed between recent CU and bipolar disorder diagnosis in our study.

Recent cannabis or methamphetamine use has led to health, social, legal, and financial consequences for participants. Moreover, individuals with recent MU have experienced these issues to a greater extent. In line with our findings, previous research has highlighted the consequences of CU, which can include impaired cognition, mental health issues, and potential long-term negative effects on motivation and academic or occupational performance (32-34). Research also shows that individuals who engage in regular MU experience a wide range of health and social consequences, including but not limited to weight loss, depression, hallucinations, paranoia, violence, and seizures (35).

Our study has several limitations that should be considered when interpreting the findings. First, relying on self-reports is associated with recall bias or social desirability bias, leading to possible underreporting or misclassification of substance use. Urine tests enhanced the reliability of our findings; however, they were limited to just three substances (THC, morphine, and methamphetamine) and could only measure recent substance use. Second, the cross-sectional design restricts our ability to determine the possible causal relationships and direction of the observed associations. Third, the study was conducted in a single tertiary psychiatric hospital in Tehran, Iran, which limits the generalizability of the findings to other settings or populations. Despite these limitations, this study provides valuable insights into the prevalence and characteristics of recent CU or MU among psychiatric inpatient settings in Iran.