The results of this controlled study of adolescents with BPD largely support the hypothesis that youth with BPD were self-medicating with substances of abuse. Substance-using adolescents with BPD were significantly more likely than substance-using controls to report “change in mood” as a motivation for starting to use their preferred substance, with a trend towards significance for continuing to use. We did not find differences between substance-using BPD and controls in other motivational categories of substance use.
Our findings indicate that the majority of adolescents with BPD (about 81%) use substances for reasons other than their euphorogenic properties and about 30% of BPD adolescents initiate and continue to use substances specifically to change their mood. These numbers are consistent with NESARC’s data which report that 24% of adults with mood disorders comorbid with SUD self-medicate in response to their mood symptoms.23
Our data are also similar to work with other psychiatric disorders in which continued substance use was unrelated to the euphorogenic effects of the identified substance.33
Overall, our findings add to a growing literature on self-medication and its relation with SUD in BPD and other pediatric psychiatric diagnoses (e.g. ADHD). For instance, Lerner and Schiebe34
demonstrated that adolescent substance users were likely to have a substantial comorbidity of ADHD with indications of drug use for self-medication. In our previous work with ADHD, we found that the majority of ADHD youth did not use substances for their euphorogenic effects nor did they differ from controls in their reports of substance use for the attenuation of mood, sleep, or other reasons.33
In contrast to these findings, our current work shows that adolescents with BPD were significantly more likely than controls to report initiating use and there was a trend to significance for continuing to use in order to change mood.
The differences in DUSI profiles between youth with ADHD and youth with BPD are noteworthy since they are consistent with the postulated self-medication specificity among psychiatric diagnoses and “preferred” psychoactive substances.18
Namely, ADHD adolescents unlike BPD adolescents are not expected to report initiating use of their preferred drug for mood-altering reasons since mood is not a part of the cardinal symptom domain in ADHD.
The results of our study also show that the frequency and level of severity of current cigarette use differs between adolescents with BPD and controls. Specifically, adolescents with BPD were more likely than controls to self-report a greater frequency of any cigarette use (78% BPD vs. 31% Controls, p=0.006) and problems with cigarette use (48% BPD vs. 8% Controls, p=0.02), with a trend to significance for cigarette use of “more than 20 times” (44% BPD vs. 15% Controls, p=0.09). Of interest, our findings are similar to recently reported findings of higher cigarette use and correlates in BPD compared to non-mood disordered controls.35
Given the public health implications of smoking cigarettes, the link between BPD and nicotine dependence from a self-medication perspective requires further investigation.
Another finding was the trend to significance for the preferred marijuana use in BPD adolescents compared to controls (41% vs. 15%, p=0.1, trend
). While a trend, this finding is consistent with the literature argument that cannabis may have potent mood effects.36
Contrary to previous research (i.e. Weiss et al.37
) that found an improvement in psychiatric symptoms regardless of drug choice, our results further highlight the importance of self-selection of specific compounds in context to self medication.18
Our current findings have important implications. Self-medication with substances of abuse has been linked with high rates of affective and other BPD symptoms,17,18,23
which is an important finding since mood and substance use are interconnected.38
Because of these facts, it is reasonable to suggest that early identification and treatment of severe affective dysregulation within pediatric BPD may result in reduced subsequent substance use and abuse. Specifically, attenuation of the need to self-medicate may advance primary and secondary prevention of substance abuse within BPD. For example, in one controlled study of substance abusing adolescents with BPD spectrum illness, lithium resulted in significant reductions in substance use as well as an improvement in global functioning.39
Likewise, in a study of substance abusing adults with BPD, those who had reported substance-induced improvement in BPD symptoms prior to therapy were the ones who had the greatest decrease in substance use as a result of interpersonal group therapy that challenged and dispelled the flawed logic behind their assumption.21
Further longitudinal data examining this important issue is necessary.
There are a number of important methodological limitations in the current study. Our study consisted of a largely middle class Caucasian sample ascertained from outpatient clinical referrals and advertisements. Hence, this sample may not be generalizeable to other socio-demographic groups. Although our overall sample was relatively large, the subgroup of adolescents with self-reported substance use was relatively small - limiting our sample size and statistical power. This limitation was particularly pronounced in controls and in the analysis subdivided according to preferred substances. Our assessment of the motivation for use and hence self-medication was limited to only four items on the DUSI. While valid and reliable, the DUSI does not cover all possible motivations for use, such as parental/community modeling, peer pressure, stress, and other psychiatric symptoms (anxiety, inattention, impulsivity, etc). In addition, the DUSI provides only subjective, self-report data; and the validity of differentiating between “use to get high” versus “use to change mood” is not well delineated in the literature. We also chose not to control for multiple comparisons. Using the Bonferroni adjustment alters the statistical inference of a study from the testing of a number of specific hypotheses to a test of the universal null hypotheses.40–42
This method increases the Type II error rate40,41
and raises the issue of the amount of tests to be included in the adjustment.40
We did not control for psychiatric comorbidity due to our small sample size and the high comorbidity of BPD with ADHD and CD in our sample: 16 (89%) of BPD subjects had comorbid ADHD and 19 (83%) of BPD subjects had comorbid CD. We also restricted our analyses to data derived only from the DUSI; and hence, we did not examine structured interview-derived substance abuse and dependence data for probands in addition to the DUSI. However, the DUSI has proven to be a valid and reliable measure with psychometric properties studied independently in assessing substance use, reasons for use, and problems related to the use.43,44
Despite the use of structured diagnostic interviews in this study, the diagnostic criteria for juvenile BPD remain controversial.45
However, all participants in this study underwent a two-stage diagnostic assessment as well as confirmation of the diagnosis of BPD by clinical interview. Such high level of scrutiny provides us with a significant degree of reassurance.
Despite these important methodological shortcomings, our study in context to the literature provides further evidence that BPD among adolescents is a major risk factor for substance abuse that appears to be in part related to the self-medication of mood symptomatology. These data highlight the importance of examining substance use in adolescents with serious mood dysregulation. Future studies clarifying the characteristics of substance use in context to self-medication and other intrinsic and extrinsic factors are necessary to provide more data on the prevention of SUD in BPD and other mood dysregulated states.