Background: Substance use disorders (SUDs) are a great burden on adolescent patients and treatment of these patients is often not successful. One reason for this difficulty is the high rate of co-occurring disorders. One disorder that frequently accompanies SUDs in adolescence is a Post-Traumatic Stress Disorder (PTSD). In studies it has often been reported that a large number of patients fulfill diagnostic criteria for both disorders at the same time. Several explanations for this co-occurrence exist: i) A common etiological factor (genetic predisposition, similar neurobiological pathways) might underlie the development of both disorders. ii) Various lifestyle factors that go hand-in-hand with an adolescent SUD (risky sexual behavior, violent dark markets) might expose patients to circumstances that increase the rate of encountered traumatic experiences (TEs) and therefore PTSD. iii) The self-medication hypothesis, where it is posited that adolescents use drugs to medicate their PTSD symptoms, often in a very specific manner, such that particular substances are used to reduce explicit symptoms. One aim explored in this thesis is the relationship between SUD, TEs, and PTSD with regard to differences in SUD severity, patterns of substance use, the role of self-medication and the effects of SUD-specific treatment on PTSD symptomatology. Methods: Five studies are presented in chapters 2 to 6 of this thesis. Chapter 2 contains a study in which the Drug Use Disorder Identification Test (DUDIT) was evaluated for use in a psychiatric adolescent patient population. This was the first study in which the DUDIT in relation to DSM-5 criteria was evaluated, in order to try to establish cut-off scores for the presence of a SUD in adolescents. In chapter 3 an evaluation is presented of the differences in SUD severity between adolescents with a SUD (‘noTE’ group), adolescents with a SUD and a history of TE but not PTSD (‘TE’ group) and adolescents with SUD and co-occurring PTSD (‘PTSD’ group). In the study presented in chapter 4 an investigation of the differences in substance use patterns between the three groups was undertaken, along with an evaluation of the associations between PTSD symptoms and use of specific substances. In chapter 5, the role coping motives play in the relationship between substance and PTSD symptoms was established. Finally, in chapter 6 the results of a pragmatic clinical trial are presented, in which the effects of a group-based treatment manual (the DELTA program) on SUD symptoms, substance use frequency and PTSD symptoms are assessed. Results: Across all included studies in this dissertation, an instrument for the assessment of SUD in adolescents was evaluated. This was used with other instruments, to establish a link between adolescent SUD and increased rates of PTSD and substance use. Furthermore, the connection between SUD and PTSD in adolescence seems to be related to a self-medication motive. Additionally we established a treatment program that reduced SUD symptoms but failed to influence the PTSD symptoms, which indicates treatment specific to one disorder is unlikely to support reductions in the co-occurring disorder. More specifically, the results presented in chapter 2 showed that the DUDIT has excellent discriminant validity and is a valid tool for the assessment of SUD severity in a clinical adolescent population. In chapter 3, it was shown that the prevalence of TEs and PTSD in adolescents with SUD is higher than in the general adolescent population. Furthermore, the PTSD group showed a significantly higher level of SUD severity than the other two groups. In contrast to our expectations, the TE group did not differ significantly with regard to SUD severity from the noTE group. In addition, SUD severity correlated positively with the number of PTSD symptoms in each symptom cluster. The study presented in chapter 4 showed that past-month substance use frequency was nearly the same across groups and across substances, with only the use of methylenedioxymethamphetamine (MDMA) being significantly more frequent and more prominent in the PTSD group compared to the other two. Participants in the PTSD group also reported a significantly earlier age of first substance use compared to participants in the other two groups. Moreover, in this study it was shown that the presence of the avoidance symptom cluster of PTSD was related to a more frequent past-month MDMA use. The findings presented in chapter 5, confirmed the pattern detected for past-month substance use in chapter 4. The PTSD group showed a more frequent MDMA use over the past-year compared to the other two groups. Additionally, the PTSD group reported using substances more frequently for coping reasons, and the frequency of coping use motives was positively correlated with the frequency of past-year MDMA use. In this study, evidence was provided that the relationship between group membership (noTE, TE, PTSD) and MDMA use frequency is in part mediated by the relationship both variables have with coping use motives. In chapter 6 medium-sized but non-significant reductions were shown in SUD symptoms and substance use frequency as a result of the DELTA intervention. Additionally, there was no indication that the treatment program resulted in changes in PTSD symptomatology. Discussion: Several important conclusion can be derived from the studies presented in this thesis. First, a co-occurring PTSD is more prevalent in SUD patients than in the general adolescent population and is associated with higher SUD severity. Second, patients with co-occurring PTSD and SUD are distinguished from SUD patients without PTSD through their increased use of MDMA. Third, the relationship between PTSD and MDMA use is partially mediated by a coping motive, supporting the self-medication hypothesis. Finally, the treatment of co-occurring PTSD and SUD seems to require therapeutic interventions specific for each disorder. The result that PTSD symptoms are not reduced after SUD-specific treatment can be interpreted as support for the self-medication hypothesis as well, in the sense that the treatment of the consequence (SUD) does not affect the preceding factor (PTSD). However, while the above interpretation is consistent with the data presented in this thesis on substance use itself, the associated data on the occurrence of SUDs indicates, that more factors than just self-medication are relevant for the development of a SUD. Furthermore, the results of this thesis do not imply that substance use motivated by self-medication motives is harmless or even beneficial, since there was no way of assessing if self-reported, coping-motivated substance use is successful in reducing symptoms or acute psychopathology. Consequently, in future projects focus should be on developing longitudinal research designs, in order to assess if and how PTSD symptoms develop over time with regard to substance use and how substance use trajectories develop in relation to PTSD symptomatology.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:81099 |
| Date | 05 October 2022 |
| Creators | Basedow, Lukas Andreas |
| Contributors | Ehrlich, Stefan, Reis, Olaf, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.3389/fpsyg.2021.678819, 10.3389/fpsyt.2020.00559, 10.1080/20008198.2021.1968140 |
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