The aim of this study was to investigate the demographic characteristics of children and adolescents abusing alcohol and drugs and the degree of comorbid psychiatric disorders in Iranian children and adolescents. A total of 277 children and adolescents with substance use disorders were identified. Among this number of children and adolescents, 174 people (0.73%) consumed alcohol and 182 people (0.8%) had substance use disorders. The results of the previous studies conducted in different regions of Iran, shows the prevalence of 1.2–6.8% drug abuse and 9.9% alcohol abuse . Accordingly, we can argue that prevalence of substance use disorder has reduced in Iranian context. Studies conducted around the world show a higher prevalence of substance use disorder than the one in the present study [24–26]. The observed differences with regard to the prevalence of substance use disorder between the studies conducted inside and outside the country can be associated with different factors including increased awareness of the Iranian people through mass media, social media, and formal education. Recently, there is a boost in the use of the social medial applications which has accelerated the rate of information exchanges both in young and adult populations. Furthermore, local mass media frequently warns the parents about the prevalence of substance use disorder in children and adolescence. All these information exchanging vehicles might have heighted the parents and children’s awareness about the devastating effects of substance use disorder leading to lower prevalence of substance abuse in Iranian children compared to children in other countries. In other words, the increased awareness about the substance use disorder in children and adolescence can decrease the risk of neglect in children. Previous studies consistently show that negligence put the children at increased risk of substance abuse .
The current study showed that anti-anxiety and hypnotic drugs (46.15%), cannabis (37.36%) and stimulants (23.63%) had the highest consumption by children and adolescents. In the study by Gattamorta  on Spanish adolescents the prevalence of marijuana (97%) was much higher than the that of the present study. However, with regard to the prevalence of anti-anxiety drugs and stimulants, Gattamorta’s findings were similar to the findings of the present study. Mesic et al.  also showed that the marijuana was the most abused drug among students in Sarajevo and Granica. The study by Mohammadkhani  in Iran, which was conducted on 2,537 secondary students, showed that cannabis and ecstasy had the highest prevalence rate in the last month of their study. The differences observed in various studies in the prevalence of different types of substances can be associated with the amount of use or accessibility of substances in different regions, and also to different attitudes toward various types of substances in different cultural and ethnic contexts. Gibbons et al.  have pointed to the availability of substances as a variable affecting substance use and Rahimian Boogar et al.  found that certain personality traits are connected with positive attitudes and more inclination toward substance abuse. The existence of risk factors in Iranian society (e.g. economical factor, family problems, community disorganization etc.) could pave the way for the formation of positive attitudes toward substance and alcohol abuse as a way to get away from such pressures.
The present study also revealed that there is a significant difference in the prevalence of drug and alcohol consumption between boys and girls (p = 0.001). As Table 3 shows, girls are less likely to be affected by substance use disorder than boys. (OR = 0.430, 95.0, c1 = 0.306–0.566). In this regard, the Center for Behavioral Health Statistics and Quality (CBHSQ) reported the substance use disorder rate of 4.5% in girls and 4% in boys worldwide in 2016. It should be noted that findings of Ljubotina et al. (2004) and review studies (24, 26). support the impact of the gender factor on the rate and type of substance abuse. The fact of gender as a predictor of drug and alcohol abuse can be attributed to cultural and ethnic factors and social beliefs toward the use of drug and alcohol.
According to the results of the current study, the use of drugs and alcohol in the age group of 15–18 years old was significantly different from the two age groups of 6–9 and 10–14 years old (p < 0.0001). The age group of 15–18 years old also had the highest probability of substance and alcohol abuse (OR = 3.64, 0.95, C1 = 1.944–4.068). Sharmat et al (2018) also confirm a significant positive relationship between the prevalence of drug abuse and age in adolescents . They showed that the prevalence of substance abuse among adolescents increases as they get older.
The present study showed that there is a significant relationship between the level of fathers’ education and the prevalence of substance use disorder. The participants whose fathers had a bachelor or higher degree were less likely to be at the risk of drugs and alcohol abuse than others. Table 2 shows the highest prevalence of substance use disorder in families with illiterate parents. A study by Pérez et al. (2018) has shown that low literacy in parents can be a predictor of early substance abuse in adolescents . The family and the school are two main social contexts affecting the social development of the adolescents . Accordinly,parents’ literacy as a family factor can directly influence the way adolescen react to their environement. A literate parent may know more about the parental roles, more systmatically deal with the family problems, and know more sources of infomration. All these elements could avoid neglegence and reduce the likelyhood of adolescencs’ risky behaviors. In addition, parentes’ education could be connected with the socioeconomic status of the family as parents with higher education could have jobs with higher saleries. Studies show that poor socioeconomic status of the family is related to the higher prevelence of risk behaviors in adolecence [32).
Table 2 shows that there is a significant relationship between parents’ occupation and the prevalence of substance use disorder in children and adolescents participating in the current study (father's occupation with p value < 0.0001) and (mother's occupation with p value < 0.045). The results of logistic regression analysis indicated that unemployment in fathers can be a predictor of substance use disorder in children and adolescents. Droomers et al. (2003) reported a significant relationship between alcohol consumption and father's occupation in 15-year-old adolescents . According to the results of their study, adolescents whose fathers had lower-level occupations were 2 times more likely than other adolescents to be at the risk of alcohol consumption. On the other hand, Vereecken et al. (2004) did not show parents’ occupation is significantly related to alcohol consumption and smoking in adolescents . Also, in the study by Richter et al. (2009) in 28 countries, parents’ occupation was not found significantly related to alcohol consumption, smoking and cannabis abuse . Richter et al. (2009) further showed that risky behaviors of children and adolescents are rarely affected by income and social status of parents . Considering the fact that various studies point to the role of individual and environmental factors in high-risk behaviors [36–38] and also the lack of conclusive findings regarding the role of parents’ occupation in alcohol and substance abuse in adolescence, it is concluded that parents’ occupation as a predictor of substance use disorder in adolescence has a contextual nature. In other words, the way parents’ occupation is related to substance use disorder in children and adolescence could vary in different communities.
The present study indicated a psychiatric comorbidity rate of 42.5% in children and adolescents abusing alcohol and substances [39–41]. Various studies have confirmed the high comorbidity of psychiatric disorders in adolescent with substance use disorder. For example, the study of Welsh et al. (2017) on 483 individuals aged 11–24, confirms the significant relationship between the use of alcohol, marijuana, opioids and tobacco and some psychiatric disorders . In the same vein, the study of Gattamorta (2017) on adolescents referring to treatment centers showed the comorbidity of psychiatric disorders in adolescents with substance use disorder is 83.2%, which is a high rate of psychiatric disorders in adolescents with substance use disorder . All these evidences including the current study further support the existence of comorbid disorders in people with substance and alcohol use disorder.
In the present study, the highest comorbidity was related to behavioral disorders (22%), with the highest association with ODD (13.7%). The study by Gattamorta (2017) revealed that substance use disorder in adolescents is highly comorbid with ODD, OCD, and ADHD, which is in line with the findings of the current study . Also, Razali and Kliewer's study (2015) on 895 adolescents with age average of 17.5 showed that early appearance of antisocial behaviors is a common long-term effect of drug abuse . Based on Molina et al. (2018), early use of alcohol, cigarettes, marijuana and other illegal drugs in adolescents with ADHD was 57%, which was more than that of the NON-ADHD people (41%) . The early use alcohol and other illegal substances other than marijuana was also reported in ADHD adolescents . The results of the current study and those of the current one further highlight the importance of comorbid disorders in children and adolescence with substance use disorder. Although such disorders could be present before or along with the substance abuse, it is necessary to deal with them for both prevention and treatment of substance use disorder. For example, Swendsen et al. (2010) reported behavioral disorders as significant risk factors of substance use disorder . Hence, early diagnosis and treatment of these disorders could have positive role in preventing later substance use disorder. Additionally, the co-occurrence of comorbid disorders with substance use disorder would hinder the substance use disorder treatment as comorbid disorders could have been the main risk factors for the substance use disorder.
In the present study, after behavioral disorders, substance use disorder in children and adolescents was highly comorbid with anxiety disorders (18.4%). Also, the results of this study showed that separation anxiety was associated with substance use disorder more than other anxiety disorders. What is common in all anxiety disorders is an experience of fear and apprehension coupled with various physical symptoms mediated by the autonomic nervous system . Several studies show that different types of drug abuse co-occur with anxiety disorders [44, 46, 47]. A study by Legerstee et al. (2010) found that children with anxiety disorders encounter significantly more unpleasant experiences than their peers which can reduce their function and cause secondary increase in their anxiety . Their study showed that the intensity of anxiety can lead to inappropriate behavior patterns and the use of ineffective coping strategies to deal with anxiety. In explaining the comorbidity of substance use disorder and anxiety disorders, self-regulation theory can be drawn on. Accordingly, it can be mentioned that when a child or teenager experiences anxiety, it is possible that he/she is not consciously capable of managing his/her behavior, thoughts and emotions to use more effective coping strategies. Such lack of self-regulation capacity may impel the children and adolescents toward harmful and destructive behaviors to control their physical and mental stress. Self-regulation can be defined as one’s ability to manage emotions, desires, and impulses and it is suggested that poor self-regulation is connected to risky behaviors . Quinn & Fromme (2010) found that high self-regulation inversely predicts heavy episodic drinking, alcohol-related problem, and unprotected sex .
In the field of mood disorders, several studies have pointed to the comorbidity of mood disorders and substance use disorder between 16% and 54% in various studies [51–53]. Such comorbidity rates are more than the one observed in the present study (5.9%). The observed difference may be attributed to the differences in the samples’ characteristics, differences in the questionnaire used, and other demographic and socioeconomic characteristics of the groups in the current study.