The present study aimed to investigate the frequency of smoking, alcohol consumption, and substance abuse in relation to general health indicators among the students of Guilan University of Medical Sciences in 2020. The differences in frequency of substance use were also examined from 2005. According to the findings, the frequency of substance use has increased over the past years among medical students at GUMS. Figures 2 and 3 demonstrate the changes in the prevalence of substance consumption within 15 years after the previous study among GUMS students. Apart from opium whose frequency changes were not statistically significant, there was a significant increase in consumption of other substances in recent and lifetime abuse.

A similar study by Zarrabi et al on the prevalence of substance use among the students of GUMS from 2005 to 2006 showed at least 30.1% of students used substance once in their lifetime. It was also found that 26.36% of students used cigarettes, 17.04% alcohol, 3.86% opium, 2.78% hashish, 2.05% ecstasy, and 1.08% used heroin.³

The frequency of substance use in some domestic^2,7,30-32 and foreign^11,33 studies was compared with the present study. In this study, the lifetime consumption of all tobacco products was 46.8%, which was higher compared to the results of other studies. This increase might be partly related to hookah, traditionally used in Iran. In domestic studies, the prevalence of cigarette smoking and using hookah was investigated either separately or totally (Table 6).

Lifetime consumption of alcohol in the current study was 34%, which was higher than in other studies in Iran. The studies by Afrashteh et al³² and Mozafarinia et al³¹ showed a higher prevalence of alcohol consumption, similar to the findings of the present study. A comparison of the frequency of alcohol abuse among students inside and outside Iran indicated that the frequency of alcohol abuse abroad was several times higher than that inside the country, which can partly be due to the religious and legal prohibition of alcohol consumption in Iran. The consumption of opioids in this study was equal to or less than that in previous studies, while the present study showed a higher use of cannabinoids compared to all domestic studies.

In terms of recent substance use, the results of the present study were compared with those of some domestic studies as shown in Table 7. The highest frequency of recent cannabis use was reported by Afrashteh et al.³² Although the lifetime consumption of alcohol in the present study (34.7%) was different from that of similar studies in Iran, this difference was not observed in recent consumption. In a meta-analysis study on Iranian university students, the one-year prevalence was reported at 23% for alcohol use, 21% for cigarette smoking, and 14% for other substances.⁴

In the current study, there was a significant relationship between age group and consumption of cigarettes, alcohol, and substances during the lifetime and the last three months. The relative frequency of consumption was higher in older age groups. This finding was consistent with that of the studies by Zarrabi et al³ and Akbari et al.³⁰

Based on the results of this study, no significant relationship was found between gender and consumption of cigarettes, alcohol, and substances during the lifetime and the last three months, which was not in line with most studies in Iran and abroad.^3,7,11,30 However, the results of the study by Armani Kian‎ et al² were consistent with those of the current study. In addition, the results of the study by Mozafarinia et al³¹ showed alcohol and cigarette consumption had no significant association with gender. This finding might indicate that the consumption of cigarettes, alcohol, and substances has increased in women compared to men in recent years. The studies close to the current study made similar conlcusions.^2,31

The present study also indicated that the history of substance abuse in the family had a significant relationship with the history of smoking, alcohol consumption, and substance use during the lifetime and the last three months. It can be due to the availability of these substances and familiarity with them at younger ages. Various studies have implicated that the presence of a substance abuser in the family is effective on the tendency of other family members to use substances.³⁴

This study showed a significant relationship between higher education level and consumption of cigarettes, alcohol, and substances during the lifetime and the last three months in medical students, which was consistent with some previous studies in other countries.^2,16 More work pressure and stress at higher levels due to direct communication with the patients and the rigors of the internship period may be a reason for the greater tendency of this group to use substances.¹⁸

In the current study, substance use in the last three months was significantly higher among students with lower GPAs. In the study on French medical students by Gignon et al, the probability of failure in medical school exams was higher among cannabis users than non-users.³³

In the current study, 49.5% of the medical students had some degree of mental disorders. This result was consistent with the findings of other studies among Iranian university students, whose reports were between 19% and 55%.^35-37 Besides, in the meta-analysis study conducted by Zare et al, mental disorders were significantly heterogeneous among university students, and almost 33% of students were suspected of having mental disorders, which gradually increased over time.²⁶

In addition, substance use during the lifetime had a significant association with anxiety, depression, and general health of the students. However, there was no significant relationship between physical health status and substance use and between social functioning and substance use. Depression and anxiety could increase the chance of substance use during the lifetime in the study group by 2.6 and 2.8 times, respectively. Symptoms of depression were common in substance abusers. Almost one-third to one-half of all people with opioid addiction or abuse and 40% of people with alcohol addiction showed symptoms of major depression at some point in their lives.³⁴ Indeed, the primary anxiety and mood disorders in patients might have led to drug use. Meanwhile, long-term drug use might lead to substance-induced mood and anxiety disorders.

In the current study, only anxiety disorder, as one of the general health variables, had a significant relationship with recent substance use (last three months) in students. Many people drink alcohol to relieve their anxiety symptoms. Phobia and panic are particularly common in alcohol users.³⁴ Alcohol, like benzodiazepine, facilitates the inhibitory function of GABA receptors. A study by Walters et al, on university students in 2018, showed no significant relationship between substance abuse in the last year and anxiety symptoms, which was contrary to the findings of the present study.³⁸ Furthermore, a study on Canadian students found that the simultaneous presence of depression and anxiety symptoms in women increased the chance of being in a group of multiple substance abusers by four times. This chance was reported to be 2.5 times in men.³⁹

According to the results, the frequency of substance use among medical students of GUMS increased significantly during the last two decades. Furthermore, recent studies in other universities of medical sciences have shown similar results, which indicate an increase in the prevalence of substance consumption among medical students. It is necessary to pay more attention to this issue on the part of the policy-makers in this field and to carry out screening studies to identify students with moderate- to high-risk consumption for prevention and treatment measures. The relationship between public health and the consumption of various substances highlights the need to pay attention to the physical and mental health of students. The living conditions of students, importance of academic pressures and shifts, hope for job security, and academic advancement are the topics that can be further studied.

During this study, the COVID-19 pandemic and quarantine might have affected the prevalence of substance consumption among the university students leading to a change in the students’ daily habits. Moreover, since the questionnaires were completed online, it was not possible to check the proportion of the population of each group in the sampling process.