In this study, we aimed to identify the prevalence and probable associations of anxiety-related disorders with different substances used by patients diagnosed with substance use disorder.
Anxiety disorders (AD) and substance use disorder (SUD) are remarkably common, addressing the mental health and socio-economic conditions of individuals. Several reports have shown that co-occurrence of an AD and SUD affect the clinical course and treatment outcomes to a very great extent .
Concerning the main research question, it was found that there are probably anxiety-related symptom patterns among patients with SUD. Moreover, the current study found that participants who were engaged in substance abuse were relatively young adults. In addition, a remarkable portion of the sample was at high risk of psychiatric problems regarding marital and socioeconomic status. Another important finding is that most of the participants were tobacco smokers (89.4%), but cigarette smoking was not correlated with any of the anxiety disorders. However, in a similar study by de Matos et al., tobacco dependence/abuse was significantly prevalent in individuals with agoraphobia . Another study by Ping Wu et al. on a sample of 781 adolescents revealed significant associations between cigarette smoking and AD in general among boys and girls. However, they found no evidence of associations between GAD and frequent cigarette smoking in males . Crystal and heroin were the other two common substances reported by subjects. Although opium abuse was less common than heroin abuse in this study, other investigations in Iran have introduced opioid use disorder as the most common substance disorder . However, this disagreement might be due to sample differences. As the participants of the current study were recruited from drug treatment services, the investigation by Amin-Esmaeili et al. was based on a household survey. Another possible explanation for this is that opium and opioids such as tramadol, methadone, etc. have been considered separately in this study. In addition, these findings might be indicative of a change in drug abuse patterns which needs to be addressed in future research with a wider scope. In this study, GAD was found to be the most common type of AD. This result reflects that of de Matos et al. who also reported that GAD is significantly prevalent in substance users. However, our research showed no significant correlations between a specific substance and GAD despite the high prevalence. In addition, the results indicate that cannabis, tramadol, and LSD are all associated with both PD and SAD. Regarding cannabis, different studies have shown diverse outcomes. Some studies reported that cannabis abuse was associated with SAD and GAD, but others showed no significant correlations . In this study, no correlation was found between anxiety disorders and the duration of substance use regarding to their age of substance use onset. This might be due to the interruptions of substance use during their clinical course and then the distortion of the given information. In addition, none of the anxiety disorders were correlated to the other medical diseases. A possible explanation for this is the small number of the participants suffering from other medical conditions such as infections and coronary artery disease. Therefore, broader research with a larger sample size in each subgroup of the medical conditions is recommended.
A note of caution is due here since all the participants of this study were males. Gender differences might have considerable impacts on all the patterns discussed above. It is also important to bear in mind that all of the subjects were individuals seeking treatment or further assessments for simultaneous psychiatric disorders. These patients have probably higher insight of their health conditions due to disturbing symptoms, more severe problems, and medical advice on the reference to treatment centers which leads to higher presentation of comorbidities in the clinical setting. Therefore, these results need to be interpreted with caution as it may not be indicative of the trends in general population. The findings of this study support the notion that co-occurrence of psychiatric disorders is relatively common and must be taken into consideration when assessing a patient. Another limitation of this study was the missing and unreliable data on the dosage of substance used by the participants. The substance users often give imprecise information on the dosage. Moreover, due to the diversity of the sources of provision, the dosage cannot be relied on even in case of a good medical history.
The exact cause and effect patterns in AD and SUD are not well-established yet. This is probably due to the complexity of the biopsychosocial aspects of the psychiatric disorders. Difficulty in recalling the exact sequence of symptoms by the patients might be a problem when investigating the disorders to understand which one is the primary or the secondary cause. Many Studies have supported different causality pathways including “shared vulnerability”, “precipitation”, and “self-medication” hypotheses [8, 18]. Environmental factors such as family issues, lack of education, social stress, financial problems etc. can expose an individual to both AD and SUD. In addition, genetic susceptibility plays an important role as a common predisposing factor to psychiatric disorders. This idea which has been called the “shared vulnerability” hypothesis may explain the general correlations between SUD and AD regardless of the primary/secondary disorder. Additionally, the patients with SUD may experience subsequent anxiety-related symptoms due to the use and/or withdrawal of the illicit drugs. According to the “precipitation” model, these symptoms may finally lead to a secondary AD. Moreover, patients with anxiety-related symptoms may turn to illicit drugs to relieve their symptoms. This idea is explained by the “self-medication” hypothesis. For example, cannabis use may result in panic attacks and cessation of prolonged use of it may cause nervousness, sleep difficulties, restlessness, anxiety, and depressed mood. As a result, one may engage in more use of cannabis or other illicit drugs to overcome the disturbing symptoms of intoxication or withdrawal. Furthermore, patients with social anxiety disorder may use alcohol or cannabis to fit in the challenging social situations. Since this approach brings a relatively temporary relief and positive emotion, frequent drug abuse is likely to become problematic ending up in a vicious cycle. Although different mechanisms may underlie the co-occurrence of AD and SUD, it is beyond the scope of the current study to determine the ones that apply to this study group since the main focus of this study was to investigate the co-occurrence of the disorders. It should be pointed out that anxiety symptoms may be induced by the overdose or withdrawal of the substance. In the case of intoxication or withdrawal, the related symptoms are usually severe leading to the hospitalization of the substance users. Thus, these patients are usually managed in the inpatient rather than the outpatient settings.
Nonetheless, patients with AD are probably at higher risk of developing SUD and vice versa. Since comorbidities may complicate the treatment of SUD, this issue is important not only in the initial assessments but also in follow-up sessions. Thereby, an integrated and multidisciplinary approach is needed to understand which of these disorders should be targeted in different stages of treatment and rehabilitation. A future study with a larger sample size is recommended. Further work is required to explore the temporal precedence of AD and SUD and identify possible cause and effect mechanisms.