Les objectifs de cette étude étaient de déterminer les comorbidités psychiatriques associées à la dépendance au cannabis chez des adolescents et des jeunes adultes comparativement à des témoins, et d’étudier les liens entre les diagnostics psychiatriques et les indicateurs de consommation de substances psychoactives. Cent patients, dépendants au cannabis, consultant en addictologie, ont été comparés à 82 témoins exempts de diagnostic lié à l’usage de cannabis, recrutés en population générale. En plus de la passation du MINI, les modalités de consommation de substances psychoactives étaient recueillies lors d’un entretien clinique multi-axial. La prévalence de patients présentant au moins un diagnostic psychiatrique de l’axe I du DSM-IV (hors troubles psychotiques) était de 79 %, contre 30,5 % chez les témoins (p<0,001) ; la présence d’un diagnostic multipliant par 8,6 le risque d’appartenir au groupe de patients dépendants consultants. La différence concernait la dysthymie actuelle, le trouble panique vie entière, la dépendance et l’abus d’alcool, et l’anxiété généralisée. Chez les patients, les prévalences de diagnostics psychiatriques étaient plus élevées chez les hommes (p=0,011) et les patients les plus âgés (p=0,006). Les spécificités psychiatriques caractérisées dans cet échantillon d’adolescents et jeunes adultes consultant en addictologie confirment l’importance de porter une attention particulière à la question du double diagnostic pour le déploiement de leur prise en charge.

The use of illicit substances, in particular cannabis, among French adolescents and young adults has become an important public health concern. A better understanding of the mechanisms involved in pathological substance use is nowadays critical. Psychiatric comorbidities have been previously reported in adult substance abusers but are less documented in adolescents, especially regarding cannabis dependence.

We investigated mental health problems in adolescents and young adults, seeking treatment for their problematic cannabis use, comparatively to healthy controls, taking into account the participant's gender and age. Moreover, we explored the relationships between psychiatric diagnosis and substance use modalities.

In total, 100 young patients (80 males – mean age 18.2 (SD=2.9; [14 to 25] years old)) with a cannabis dependence (DSM-IV-TR criteria) seeking treatment in an addiction unit, and 82 healthy control subjects (50 males – mean age 18.3 (SD=3.4; [14 to 25] years old)) with no substance misuse diagnostic other than for alcohol, participated in the study. The MINI was administered to evaluate cannabis dependence, and DSM-IV axis I comorbid diagnosis, and a semi-structured interview was used to determine psychoactive substance use.

Statistical analyses revealed that 79 % of the patients reported at least one other non-drug or alcohol comorbid diagnosis, versus 30.5 % in the control group (χ²=16.83; P<0.001). Logistic regression indicated that participants with a psychiatric diagnosis had an 8.6 times higher risk (P<0.001; OR 95 % CI=[4.38–16.81]) of being patients. Significant inter-group differences and OR were noted for several diagnoses: dysthymia over the previous 2years (χ²=14.06; P<0.001; OR=10.63; OR 95 % CI=[2.41–46.87]), life-time panic attack disorder (χ²=4.15; P<0.042; OR=3.59; OR 95 % CI=[0.98–13.19]), alcohol abuse (χ²=47.72; P<0.001; OR=66.27; OR 95 % CI=[8.87–495.11]) and dependence (V=0.230; P=0.001) and generalized anxiety disorder (χ²=7.46; P=0.006–OR=3.57; OR 95 % CI=[1.37–9.30]). On the whole, the females (n=20) of our clinical sample presented significantly more comorbid diagnoses than the males (n=80) (95 % versus 75 %; χ²=6.25, P=0.011). These significant gender differences were found for life-time eating disorder (V=0.352; P=0.007) and generalized anxiety disorder diagnoses (V=0.278; P=0.013). Moreover, young adult patients (19–25years old; n=35) presented, on the whole, significantly more comorbid diagnoses than adolescent patients (14–18years old; n=65) (70.8 % versus 94.3 %; χ²=7.58, P=0.006). These age inter-group differences were found for several diagnoses: alcohol dependence (6.2 % versus 20 %; V=0.211, P=0.047), dysthymia over the past 2years (13.8 % versus 34.3 %; χ²=5.73, P=0.017) and generalized anxiety disorder (12.3 % versus 40 %; χ²=10.17, P=0.001). Various associations were observed between psychiatric comorbid diagnosis and substance use indicators.

This study demonstrates that cannabis dependence in adolescents and young adults is related to great psychological distress and puts emphasis on the importance of substance use prevention as early as middle school. Moreover, the psychiatric features of adolescents and young adults need to be taken into consideration for treatment planning.