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Association between schizotypal and borderline personality disorder traits, and cannabis use in young adults
Addictive Behaviors 60 (2016) 144–147
Contents lists available at ScienceDirect
Addictive Behaviors journal homepage: www.elsevier.com/locate/addictbeh
Short Communication
Association between schizotypal and borderline personality disorder traits, and cannabis use in young adults Patrick Raynal, Henri Chabrol ⁎ CERPPS, Université de Toulouse, UT2J, France
H I G H L I G H T S • • • • •
No study focused on cannabis use, borderline and schizotypal traits. These relationships were explored in a sample of college students. Cannabis use, borderline and schizotypal traits were significantly correlated. Only borderline traits were uniquely associated to cannabis use versus non-use. Only schizotypal traits were uniquely associated to problematic cannabis use.
a r t i c l e
i n f o
Article history: Received 13 November 2015 Received in revised form 23 March 2016 Accepted 20 April 2016 Available online 22 April 2016 Keywords: Problematic cannabis use Young adults Schizotypal traits Borderline traits
a b s t r a c t The aim of the study was to examine the association of schizotypal and borderline personality traits to cannabis use. Participants were 476 college students (95 males; 381 females; mean age of males = 21; mean age of females = 20.7) who completed self-report questionnaires assessing cannabis use, schizotypal and borderline personality traits. Problematic cannabis use, depressive symptoms, borderline and schizotypal traits were significantly inter-correlated. A logistic regression analysis showed that only borderline traits contributed significantly to cannabis use in the total sample. A multiple regression analysis showed that only schizotypal traits were positively and uniquely associated to problematic cannabis use symptoms among users. These results may imply that schizotypal traits are not a risk factor for initiating use, but may facilitate the development of problematic use symptoms among users. This study showed the necessity of taking into account schizotypal traits when exploring the relationships between depressive symptoms, borderline traits and cannabis use. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Cannabis use has been found to be associated to schizotypal personality traits in young adults (Dumas et al., 2002; Skosnik, Spatz-Glenn, & Park, 2001). Young adults with high scores on schizotypal traits reported much greater frequencies of cannabis use and cannabis-related problems (Cohen, Buckner, Najolia, & Stewart, 2011). The importance of this association is linked to the finding that both cannabis use and schizotypal traits are risks factors for the development of schizophrenia in young people (e.g., McGrath et al., 2010). Prospective researches displayed conflicting results on the relationships between schizotypal traits and cannabis use: Schiffman, Nakamura, Earleywine, and LaBrie (2005) found that the onset of schizotypal traits precedes the onset of cannabis use whereas Anglin et al.'s study (2012) supported a strong ⁎ Corresponding author at: Laboratoire CERPPS, Université de Toulouse-Jean Jaurès, Maison de la Recherche, 5 Allées Antonio Machado, 31058 Toulouse Cedex 9, France. E-mail address: [email protected] (H. Chabrol).
http://dx.doi.org/10.1016/j.addbeh.2016.04.018 0306-4603/© 2016 Elsevier Ltd. All rights reserved.
association of early cannabis use with the development of schizotypal symptoms. The examination of the relationships between schizotypal traits and cannabis use may be obscured by the association of borderline personality disorder (BPD) traits to both schizotypal traits (e.g., Fonseca-Pedrero, Lemos-Giráldez, Paino, Sierra-Baigrie, & Muñiz, 2012) and cannabis use (e.g., Chabrol, Ducongé, Casas, Roura, & Carey, 2005). Borderline traits are the personality disorder traits having the greatest effects on the development of substance use disorder in adolescents (Cohen, Chen, Crawford, Brook, & Gordon, 2007). Few studies have investigated the association between schizotypal traits, borderline traits and cannabis use. Williams, Wellman, and Rawlins (1996) observed that cannabis users showed higher scores on schizotypal and borderline traits than non-users. In a small sample of high-school students, Chabrol, Melioli, and Goutaudier (2015) examined the relationships between cannabis use and the personality disorders traits identified as associated to adolescent substance use by previous studies, that is, borderline, antisocial, narcissistic, schizotypal, schizoid, avoidant and passive-aggressive personality disorder traits:
P. Raynal, H. Chabrol / Addictive Behaviors 60 (2016) 144–147
only schizotypal and borderline traits were positively and independently associated to problematic cannabis use symptoms after adjustment for anxious and depressive symptoms. Depressive symptoms have been found to be associated to cannabis use, borderline and schizotypal traits (e.g., Chabrol et al., 2005, 2015; Schwinn, Schinke, & Trent, 2010). Some studies reported gender differences in the relationships between mental health and cannabis use, and more specifically between depressive and borderline traits, and cannabis use or problematic use (e.g., Chabrol et al., 2005) but other studies did not find evidence of the influence of gender (e.g., Schwinn et al., 2010). No study explored the influence of gender on the association between schizotypal traits and cannabis use. Consequently, the aim of this study was to examine the relationships between depressive symptoms, borderline and schizotypal traits, and cannabis use and the influence of gender on these relationships.
2. Method 2.1. Participants and procedure The sample consisted of 476 college students (95 males; 381 females; mean age of males = 21 ± 2.3; mean age of females = 20.7 ± 1.9; p = 0.32). Participants were recruited through student groups active in social networks and affiliated to universities in France. The sample was composed of individuals aged between 18 and 25 and who answered N 95% of the items. The study procedures were approved by the ethics committee of the research ward. The study followed the ethical guidelines of the Helsinki Declaration. Participants provided their willingness to participate through a consent form and no compensation was offered. The questionnaires were anonymous.
2.2. Measures Cannabis use was assessed using the French version of the Cannabis Use Disorders Identification Test (CUDIT) (Annaheim, Rehm, & Gmel, 2008; Guillem et al., 2011) which is a self-reported questionnaire that evaluates the cannabis consumption over the previous 6 months and identifies problematic or harmful cannabis use. Guillem et al. found a cut-off score of 10 for the CUDIT when screening for problematic use. Schizotypal traits were assessed with the Schizotypal Personality Questionnaire Brief Form (SPQ-B; Fonseca-Pedrero, Paino-Pineiro, Lemos-Giraldez, Villazon-Garcia, & Muniz, 2009). The SPQ-B is a 22item (true/false) self-report for assessment of schizotypal personality disorder. Borderline traits were measured using the French version of the BPD scale of the Personality Diagnostic Questionnaire, Fourth Edition (PDQ-4 +; Hyler, 1994; Bouvard, 2002). The borderline scale is composed of 9 items corresponding to the DSM-IV criteria for BPD. Depressive symptoms were assessed using the short version of the Center for Epidemiologic Studies-Depression scale (CES-D-10; Andresen, Malmgren, Carter, & Patrick, 1994). Cronbach alphas and potential ranges are presented in Table 1.
145
2.3. Statistical analyses Student's t-tests were used to compare cannabis users and nonusers, and problematic users and non-problematic users. Bivariate relationships between variables were assessed with Pearson's r. The association of personality traits with cannabis use was examined in a logistic regression analysis predicting cannabis use versus non-use, entering gender, depressive symptoms, borderline and schizotypal traits. Results were reported with standardized regression coefficients of the explanatory variables (B) and p values. Predictors were standardized to get standardized regression coefficients. The association of personality traits to the CUDIT scores was tested with a hierarchical multiple regression analysis including all independent variables. The proportion of variance explained at each step was evaluated by the incremental F ratio. The unique association of each independent variable was reported with standardized regression coefficient (β) and p value. To determine whether gender moderated the relationship between psychopathological variables and problematic cannabis use, interaction terms (gender × depressive symptoms, gender × borderline traits, gender × schizotypal traits) were included in the last step of the multiple regression analysis. All variables mean centered with the exception of gender which was coded as −1 for females, and 1 for males. All statistical analyses were performed using STATISTICA, Version 10. 3. Results 3.1. Descriptive statistics In the total sample, 32% of males (n = 30, age = 21.5 ± 2.5) and 30% of females (n = 112, age = 20.6 ± 1.3) reported having used cannabis at least once during the last 6 months (p = 0.91). Among cannabis users, CUDIT total score did not differ between males and females (7.6 ± 7.1 vs 7.1 ± 7.3, t = 0.16, p b 0.87). Similarly, the proportion of users with problematic cannabis use (CUDIT scores ≥10) did not differ between males and females (27% versus 29%, p = 0.84). Users had higher scores on borderline traits than non-users. Problematic users had higher scores on schizotypal and borderline traits than nonproblematic users (Table 1). 3.2. Correlations between variables in the total sample The CUDIT score was weakly associated to depressive symptoms (r = 0.11, p b 0.05), moderately associated to borderline traits (r = 0.28, p b 0.05) and more weakly to schizotypal traits (r = 0.18, p b 0.05). The relationship between schizotypal traits and borderline traits was moderate (r = 0.58, p b 0.05). Depressive symptoms were moderately associated to borderline traits (r = 0.61, p b 0.05) and schizotypal traits (r = 0.51, p b 0.05). 3.3. Logistic regression analysis predicting cannabis use versus non-use in the total sample The predictors reliably distinguished between users and non-users, χ2 (4) = 28.5, p b 0.0001. Borderline traits were the only significant independent predictor of cannabis use (B = 0.70, p b 0.0001). Gender
Table 1 Comparisons between cannabis users and non-users and between cannabis users with and without problematic use. Variable
α
Range
Non-users (n = 332) M (SD)
Users (n = 142) M (SD)
t (472)
p
Non-problematic users (n = 102) M (SD)
Problematic users (n = 40) M (SD)
t (140)
p
CUDIT Depressive symptoms Schizotypal traits Borderline traits
0.87 0.81 0.78 0.84
0–40 0–30 0–22 0–54
0.15 (0.87) 12.58 (4.02) 8.24 (4.44) 20.70 (10.82)
7.18 (7.26) 13.16 (4.21) 8.95 (4.36) 26.34 (12.15)
−17.37 −1.44 −1.60 −5.01
b0.001 0.15 0.11 b0.001
3.27 (1.71) 12.82 (4.05) 8.14 (3.89) 24.14 (11.05)
17.13 (6.45) 14.03 (4.53) 11.03 (4.85) 31.95 (13.13)
−20.07 −1.54 −3.70 −3.59
b0.001 0.13 b0.001 b0.001
Note: CUDIT = Cannabis Use Disorders Identification Test; problematic users scored ≥10 on CUDIT; non-problematic users scored b10.
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P. Raynal, H. Chabrol / Addictive Behaviors 60 (2016) 144–147
was not a significant predictor (B = 0.08, p b 0.75), nor depressive symptoms (B = −0.20, p = 0.14) and schizotypal traits (B = − 0.15, p = 0.27). 3.4. Multiple regression analysis predicting CUDIT scores in the sub-sample of cannabis users Gender and depressive symptoms were entered in the first step (Table 2). Depressive symptoms were the only significant predictor. In the second step, borderline traits were added, accounting for a significant increase of explained variance. Borderline traits was the only significant predictor. Depressive symptoms were no more a significant predictor. In the third step, the addition of schizotypal traits significantly increased the explained variance. Schizotypal traits were the only significant predictor, while borderline traits symptoms were no more a significant predictor. The last step tested for the moderating effect of gender. It included interaction terms between gender and depressive symptoms, borderline, and schizotypal traits. None of the interaction term was significant. Gender did not appear to moderate the association of depressive symptoms, borderline, and schizotypal traits with problematic cannabis use. 4. Discussion In our sample, the strong positive relationships between schizotypal and borderline traits confirmed the possibility that borderline traits may contribute to the association between schizotypal traits and cannabis use and the interest of taking into account borderline traits in examining the relationships between schizotypal traits and cannabis use. Logistic regression analysis showed that only borderline traits were uniquely associated to cannabis use in the total sample. Schizotypal traits did not appear to contribute to cannabis use in the total sample. Among cannabis users, multiple regression analysis found that only schizotypal traits were significantly and uniquely associated to problematic cannabis use symptoms. These results are compatible with the possibility that schizotypal traits are not a risk factor for initiating use, but may facilitate the development of problematic use among users. Schizotypal traits may lead to problematic use through selfmedication: cannabis can temporarily alleviate schizotypal or psychotic symptoms while worsening them secondarily, leading to increased need for use (e.g., Ferdinand et al., 2005). Table 2 Hierarchical multiple regression analyses predicting CUDIT scores in users (n = 142). ΔR2 Step 1 Gender Depressive symptoms Step 2 Gender Depressive symptoms Borderline traits Step 3 Gender Depressive symptoms Borderline traits Schizotypal traits Step 4 Gender Depressive symptoms Borderline traits Schizotypal traits Gender × depressive symptoms Gender × borderline traits Gender × schizotypal traits Total R2
β
p
−0.04 0.19
0.62 0.02
−0.02 0.01 0.31
0.79 0.93 0.002
−0.01 0.04 0.18 0.24
0.89 0.72 0.12 0.02
−0.01 −0.05 0.15 0.29 0.03 0.04 −0.08
0.91 0.68 0.31 0.03 0.83 0.80 0.55
0.04
0.06⁎
0.03⁎
0.002
0.13
Note: CUDIT = Cannabis Use Disorders Identification Test. ⁎ p b 0.01.
Depressive symptoms were not uniquely associated to cannabis use and problematic use when controlling for borderline traits, in concordance with Chabrol et al. (2005), highlighting the necessity of taking into account borderline traits when studying the relationship between depressive symptoms and cannabis use in adolescents and young adults. Gender did not moderate any of the associations between depressive symptoms, borderline, and schizotypal traits and problematic cannabis use, in concordance with the study by Schwinn et al. (2010) which did not found evidence of a moderating effect of gender on the relationship between mental health and substance use. This study has several limitations. Mainly, the cross-sectional design prevents from inferring causal relationships. Longitudinal studies are needed to clarify the causal relationships between borderline and schizotypal traits and problematic use. The relationships suggested by our study could be considered as support for potential pathways to be further explored in longitudinal studies. However, this study suggests the importance of evaluating borderline and schizotypal traits, in studies of risk factors or consequences of cannabis use. Role of funding sources This study received no funding. Contributors Patrick Raynal and Henri Chabrol designed the study and conducted the statistical analyses. Henri Chabrol wrote the first draft of the manuscript and both authors contributed to and have approved the final manuscript. Declaration of interest The authors report no conflicts of interest.
References Andresen, E. M., Malmgren, J. A., Carter, W. B., & Patrick, D. L. (1994). Screening for depression in well older adults: Evaluation of a short form of the CES-D. American Journal of Preventive Medicine, 10, 77–84. Anglin, D. M., Corcoran, C. M., Brown, A. S., Chen, H., Lighty, Q., Brook, J. S., & Cohen, P. R. (2012). Early cannabis use and schizotypal personality disorder symptoms from adolescence to middle adulthood. Schizophrenia Research, 137, 45–49. http://dx.doi. org/10.1016/j.schres.2012.01.019. Annaheim, B., Rehm, J., & Gmel, G. (2008). How to screen for problematic cannabis use in population surveys. An evaluation of the Cannabis Use Disorders Identification Test (CUDIT) in a Swiss sample of adolescents and young adults. European Addiction Research, 14, 190–197. http://dx.doi.org/10.1159/000141643. Bouvard, M. (2002). Questionnaires et échelles d'évaluation de la personnalité [Questionnaires and scales assessing personality]. Paris: Masson. Chabrol, H., Ducongé, H., Casas, C., Roura, C., & Carey, K. (2005). Relations between cannabis use and dependence, motives for cannabis use and anxious, depressive and borderline symptomatology. Addictive Behaviors, 30, 829–840. http://dx.doi.org/10. 1016/j.addbeh.2004.08.027. Chabrol, H., Melioli, T., & Goutaudier, N. (2015). Association between personality disorders traits and problematic cannabis use in adolescents. Substance Use & Misuse, 50, 552–556. http://dx.doi.org/10.3109/10826084.2014.984851. Cohen, A. S., Buckner, J. D., Najolia, G. M., & Stewart, D. W. (2011). Cannabis and psychometrically-defined schizotypy: Use, problems and treatment considerations. Journal of Psychiatric Research, 45(4), 548–554. http://dx.doi.org/10.1016/j. jpsychires.2010.08.013. Cohen, P., Chen, H., Crawford, T. N., Brook, J. S., & Gordon, K. (2007). Personality disorders in early adolescence and the development of later substance use in the general population. Drug and Alcohol Dependence, 88, S71–S84 (doi: 10.1016%2Fj.drugalcdep. 2006.12.012). Dumas, P., Saoud, M., Bouafia, S., Gutknecht, C., Ecochard, R., Daléry, J., ... d'Amato, T. (2002). Cannabis use correlates with schizotypal personality traits in healthy students. Psychiatry Research, 109(1), 27–35. http://dx.doi.org/10.1016/S01651781(01)00358-4. Ferdinand, R. F., Sondeijker, F., Van Der Ende, J., Selten, J. P., Huizink, A., & Verhulst, F. C. (2005). Cannabis use predicts future psychotic symptoms, and vice versa. Addiction, 100(5), 612–618. http://dx.doi.org/10.1111/j.1360-0443.2005.01070.x. Fonseca-Pedrero, E., Lemos-Giráldez, S., Paino, M., Sierra-Baigrie, S., & Muñiz, J. (2012). Relationship between schizotypal and borderline traits in college students. The Spanish Journal of Psychology, 15(01), 306–314. http://dx.doi.org/10.5209/rev_SJOP. 2012.v15.n1.37337. Fonseca-Pedrero, E., Paino-Pineiro, M., Lemos-Giraldez, S., Villazon-Garcia, U., & Muniz, J. (2009). Validation of the Schizotypal Personality Questionnaire-Brief Form in adolescents. Schizophrenia Research, 111, 53–60. http://dx.doi.org/10.1016/j.schres.2009.03. 006. Guillem, E., Notides, C., Debray, M., Vorspan, F., Musa, C., Nieto, I., ... Lépine, J. P. (2011). Psychometric properties of the Cannabis Use Disorders Identification Test in French
P. Raynal, H. Chabrol / Addictive Behaviors 60 (2016) 144–147 cannabis misusers. Journal of Addictions Nursing, 22, 1–8. http://dx.doi.org/10.3109/ 10884602.2011.616604. Hyler, S. E. (1994). Personality Diagnostic Questionnaire (PDQ-4+). New York: New York State Psychiatric Institute. McGrath, J., Welham, J., Scott, J., Varghese, D., Degenhardt, L., Hayatbakhsh, M. R., ... Najman, J. M. (2010). Association between cannabis use and psychosis-related outcomes using sibling pair analysis in a cohort of young adults. Archives of General Psychiatry, 67(5), 440–447. http://dx.doi.org/10.1001/archgenpsychiatry.2010.6. Schiffman, J., Nakamura, B., Earleywine, M., & LaBrie, J. (2005). Symptoms of schizotypy precede cannabis use. Psychiatry Research, 134(1), 37–42. http://dx.doi.org/10.1016/ j.psychres.2005.01.004.
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Schwinn, T. M., Schinke, S. P., & Trent, D. N. (2010). Substance use among late adolescent urban youths: Mental health and gender influences. Addictive Behaviors, 35(1), 30–34. http://dx.doi.org/10.1016/j.addbeh.2009.08.005. Skosnik, P. D., Spatz-Glenn, L., & Park, S. (2001). Cannabis use is associated with schizotypy and attentional disinhibition. Schizophrenia Research, 48(1), 83–92. http://dx.doi.org/10.1016/S0920-9964(00)00132-8. Williams, J. H., Wellman, N. A., & Rawlins, J. N. P. (1996). Cannabis use correlates with schizotypy in healthy people. Addiction, 91(6), 869–877. http://dx.doi.org/10.1046/j. 1360-0443.1996.91686912.x.
Contents lists available at ScienceDirect
Addictive Behaviors journal homepage: www.elsevier.com/locate/addictbeh
Short Communication
Association between schizotypal and borderline personality disorder traits, and cannabis use in young adults Patrick Raynal, Henri Chabrol ⁎ CERPPS, Université de Toulouse, UT2J, France
H I G H L I G H T S • • • • •
No study focused on cannabis use, borderline and schizotypal traits. These relationships were explored in a sample of college students. Cannabis use, borderline and schizotypal traits were significantly correlated. Only borderline traits were uniquely associated to cannabis use versus non-use. Only schizotypal traits were uniquely associated to problematic cannabis use.
a r t i c l e
i n f o
Article history: Received 13 November 2015 Received in revised form 23 March 2016 Accepted 20 April 2016 Available online 22 April 2016 Keywords: Problematic cannabis use Young adults Schizotypal traits Borderline traits
a b s t r a c t The aim of the study was to examine the association of schizotypal and borderline personality traits to cannabis use. Participants were 476 college students (95 males; 381 females; mean age of males = 21; mean age of females = 20.7) who completed self-report questionnaires assessing cannabis use, schizotypal and borderline personality traits. Problematic cannabis use, depressive symptoms, borderline and schizotypal traits were significantly inter-correlated. A logistic regression analysis showed that only borderline traits contributed significantly to cannabis use in the total sample. A multiple regression analysis showed that only schizotypal traits were positively and uniquely associated to problematic cannabis use symptoms among users. These results may imply that schizotypal traits are not a risk factor for initiating use, but may facilitate the development of problematic use symptoms among users. This study showed the necessity of taking into account schizotypal traits when exploring the relationships between depressive symptoms, borderline traits and cannabis use. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Cannabis use has been found to be associated to schizotypal personality traits in young adults (Dumas et al., 2002; Skosnik, Spatz-Glenn, & Park, 2001). Young adults with high scores on schizotypal traits reported much greater frequencies of cannabis use and cannabis-related problems (Cohen, Buckner, Najolia, & Stewart, 2011). The importance of this association is linked to the finding that both cannabis use and schizotypal traits are risks factors for the development of schizophrenia in young people (e.g., McGrath et al., 2010). Prospective researches displayed conflicting results on the relationships between schizotypal traits and cannabis use: Schiffman, Nakamura, Earleywine, and LaBrie (2005) found that the onset of schizotypal traits precedes the onset of cannabis use whereas Anglin et al.'s study (2012) supported a strong ⁎ Corresponding author at: Laboratoire CERPPS, Université de Toulouse-Jean Jaurès, Maison de la Recherche, 5 Allées Antonio Machado, 31058 Toulouse Cedex 9, France. E-mail address: [email protected] (H. Chabrol).
http://dx.doi.org/10.1016/j.addbeh.2016.04.018 0306-4603/© 2016 Elsevier Ltd. All rights reserved.
association of early cannabis use with the development of schizotypal symptoms. The examination of the relationships between schizotypal traits and cannabis use may be obscured by the association of borderline personality disorder (BPD) traits to both schizotypal traits (e.g., Fonseca-Pedrero, Lemos-Giráldez, Paino, Sierra-Baigrie, & Muñiz, 2012) and cannabis use (e.g., Chabrol, Ducongé, Casas, Roura, & Carey, 2005). Borderline traits are the personality disorder traits having the greatest effects on the development of substance use disorder in adolescents (Cohen, Chen, Crawford, Brook, & Gordon, 2007). Few studies have investigated the association between schizotypal traits, borderline traits and cannabis use. Williams, Wellman, and Rawlins (1996) observed that cannabis users showed higher scores on schizotypal and borderline traits than non-users. In a small sample of high-school students, Chabrol, Melioli, and Goutaudier (2015) examined the relationships between cannabis use and the personality disorders traits identified as associated to adolescent substance use by previous studies, that is, borderline, antisocial, narcissistic, schizotypal, schizoid, avoidant and passive-aggressive personality disorder traits:
P. Raynal, H. Chabrol / Addictive Behaviors 60 (2016) 144–147
only schizotypal and borderline traits were positively and independently associated to problematic cannabis use symptoms after adjustment for anxious and depressive symptoms. Depressive symptoms have been found to be associated to cannabis use, borderline and schizotypal traits (e.g., Chabrol et al., 2005, 2015; Schwinn, Schinke, & Trent, 2010). Some studies reported gender differences in the relationships between mental health and cannabis use, and more specifically between depressive and borderline traits, and cannabis use or problematic use (e.g., Chabrol et al., 2005) but other studies did not find evidence of the influence of gender (e.g., Schwinn et al., 2010). No study explored the influence of gender on the association between schizotypal traits and cannabis use. Consequently, the aim of this study was to examine the relationships between depressive symptoms, borderline and schizotypal traits, and cannabis use and the influence of gender on these relationships.
2. Method 2.1. Participants and procedure The sample consisted of 476 college students (95 males; 381 females; mean age of males = 21 ± 2.3; mean age of females = 20.7 ± 1.9; p = 0.32). Participants were recruited through student groups active in social networks and affiliated to universities in France. The sample was composed of individuals aged between 18 and 25 and who answered N 95% of the items. The study procedures were approved by the ethics committee of the research ward. The study followed the ethical guidelines of the Helsinki Declaration. Participants provided their willingness to participate through a consent form and no compensation was offered. The questionnaires were anonymous.
2.2. Measures Cannabis use was assessed using the French version of the Cannabis Use Disorders Identification Test (CUDIT) (Annaheim, Rehm, & Gmel, 2008; Guillem et al., 2011) which is a self-reported questionnaire that evaluates the cannabis consumption over the previous 6 months and identifies problematic or harmful cannabis use. Guillem et al. found a cut-off score of 10 for the CUDIT when screening for problematic use. Schizotypal traits were assessed with the Schizotypal Personality Questionnaire Brief Form (SPQ-B; Fonseca-Pedrero, Paino-Pineiro, Lemos-Giraldez, Villazon-Garcia, & Muniz, 2009). The SPQ-B is a 22item (true/false) self-report for assessment of schizotypal personality disorder. Borderline traits were measured using the French version of the BPD scale of the Personality Diagnostic Questionnaire, Fourth Edition (PDQ-4 +; Hyler, 1994; Bouvard, 2002). The borderline scale is composed of 9 items corresponding to the DSM-IV criteria for BPD. Depressive symptoms were assessed using the short version of the Center for Epidemiologic Studies-Depression scale (CES-D-10; Andresen, Malmgren, Carter, & Patrick, 1994). Cronbach alphas and potential ranges are presented in Table 1.
145
2.3. Statistical analyses Student's t-tests were used to compare cannabis users and nonusers, and problematic users and non-problematic users. Bivariate relationships between variables were assessed with Pearson's r. The association of personality traits with cannabis use was examined in a logistic regression analysis predicting cannabis use versus non-use, entering gender, depressive symptoms, borderline and schizotypal traits. Results were reported with standardized regression coefficients of the explanatory variables (B) and p values. Predictors were standardized to get standardized regression coefficients. The association of personality traits to the CUDIT scores was tested with a hierarchical multiple regression analysis including all independent variables. The proportion of variance explained at each step was evaluated by the incremental F ratio. The unique association of each independent variable was reported with standardized regression coefficient (β) and p value. To determine whether gender moderated the relationship between psychopathological variables and problematic cannabis use, interaction terms (gender × depressive symptoms, gender × borderline traits, gender × schizotypal traits) were included in the last step of the multiple regression analysis. All variables mean centered with the exception of gender which was coded as −1 for females, and 1 for males. All statistical analyses were performed using STATISTICA, Version 10. 3. Results 3.1. Descriptive statistics In the total sample, 32% of males (n = 30, age = 21.5 ± 2.5) and 30% of females (n = 112, age = 20.6 ± 1.3) reported having used cannabis at least once during the last 6 months (p = 0.91). Among cannabis users, CUDIT total score did not differ between males and females (7.6 ± 7.1 vs 7.1 ± 7.3, t = 0.16, p b 0.87). Similarly, the proportion of users with problematic cannabis use (CUDIT scores ≥10) did not differ between males and females (27% versus 29%, p = 0.84). Users had higher scores on borderline traits than non-users. Problematic users had higher scores on schizotypal and borderline traits than nonproblematic users (Table 1). 3.2. Correlations between variables in the total sample The CUDIT score was weakly associated to depressive symptoms (r = 0.11, p b 0.05), moderately associated to borderline traits (r = 0.28, p b 0.05) and more weakly to schizotypal traits (r = 0.18, p b 0.05). The relationship between schizotypal traits and borderline traits was moderate (r = 0.58, p b 0.05). Depressive symptoms were moderately associated to borderline traits (r = 0.61, p b 0.05) and schizotypal traits (r = 0.51, p b 0.05). 3.3. Logistic regression analysis predicting cannabis use versus non-use in the total sample The predictors reliably distinguished between users and non-users, χ2 (4) = 28.5, p b 0.0001. Borderline traits were the only significant independent predictor of cannabis use (B = 0.70, p b 0.0001). Gender
Table 1 Comparisons between cannabis users and non-users and between cannabis users with and without problematic use. Variable
α
Range
Non-users (n = 332) M (SD)
Users (n = 142) M (SD)
t (472)
p
Non-problematic users (n = 102) M (SD)
Problematic users (n = 40) M (SD)
t (140)
p
CUDIT Depressive symptoms Schizotypal traits Borderline traits
0.87 0.81 0.78 0.84
0–40 0–30 0–22 0–54
0.15 (0.87) 12.58 (4.02) 8.24 (4.44) 20.70 (10.82)
7.18 (7.26) 13.16 (4.21) 8.95 (4.36) 26.34 (12.15)
−17.37 −1.44 −1.60 −5.01
b0.001 0.15 0.11 b0.001
3.27 (1.71) 12.82 (4.05) 8.14 (3.89) 24.14 (11.05)
17.13 (6.45) 14.03 (4.53) 11.03 (4.85) 31.95 (13.13)
−20.07 −1.54 −3.70 −3.59
b0.001 0.13 b0.001 b0.001
Note: CUDIT = Cannabis Use Disorders Identification Test; problematic users scored ≥10 on CUDIT; non-problematic users scored b10.
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was not a significant predictor (B = 0.08, p b 0.75), nor depressive symptoms (B = −0.20, p = 0.14) and schizotypal traits (B = − 0.15, p = 0.27). 3.4. Multiple regression analysis predicting CUDIT scores in the sub-sample of cannabis users Gender and depressive symptoms were entered in the first step (Table 2). Depressive symptoms were the only significant predictor. In the second step, borderline traits were added, accounting for a significant increase of explained variance. Borderline traits was the only significant predictor. Depressive symptoms were no more a significant predictor. In the third step, the addition of schizotypal traits significantly increased the explained variance. Schizotypal traits were the only significant predictor, while borderline traits symptoms were no more a significant predictor. The last step tested for the moderating effect of gender. It included interaction terms between gender and depressive symptoms, borderline, and schizotypal traits. None of the interaction term was significant. Gender did not appear to moderate the association of depressive symptoms, borderline, and schizotypal traits with problematic cannabis use. 4. Discussion In our sample, the strong positive relationships between schizotypal and borderline traits confirmed the possibility that borderline traits may contribute to the association between schizotypal traits and cannabis use and the interest of taking into account borderline traits in examining the relationships between schizotypal traits and cannabis use. Logistic regression analysis showed that only borderline traits were uniquely associated to cannabis use in the total sample. Schizotypal traits did not appear to contribute to cannabis use in the total sample. Among cannabis users, multiple regression analysis found that only schizotypal traits were significantly and uniquely associated to problematic cannabis use symptoms. These results are compatible with the possibility that schizotypal traits are not a risk factor for initiating use, but may facilitate the development of problematic use among users. Schizotypal traits may lead to problematic use through selfmedication: cannabis can temporarily alleviate schizotypal or psychotic symptoms while worsening them secondarily, leading to increased need for use (e.g., Ferdinand et al., 2005). Table 2 Hierarchical multiple regression analyses predicting CUDIT scores in users (n = 142). ΔR2 Step 1 Gender Depressive symptoms Step 2 Gender Depressive symptoms Borderline traits Step 3 Gender Depressive symptoms Borderline traits Schizotypal traits Step 4 Gender Depressive symptoms Borderline traits Schizotypal traits Gender × depressive symptoms Gender × borderline traits Gender × schizotypal traits Total R2
β
p
−0.04 0.19
0.62 0.02
−0.02 0.01 0.31
0.79 0.93 0.002
−0.01 0.04 0.18 0.24
0.89 0.72 0.12 0.02
−0.01 −0.05 0.15 0.29 0.03 0.04 −0.08
0.91 0.68 0.31 0.03 0.83 0.80 0.55
0.04
0.06⁎
0.03⁎
0.002
0.13
Note: CUDIT = Cannabis Use Disorders Identification Test. ⁎ p b 0.01.
Depressive symptoms were not uniquely associated to cannabis use and problematic use when controlling for borderline traits, in concordance with Chabrol et al. (2005), highlighting the necessity of taking into account borderline traits when studying the relationship between depressive symptoms and cannabis use in adolescents and young adults. Gender did not moderate any of the associations between depressive symptoms, borderline, and schizotypal traits and problematic cannabis use, in concordance with the study by Schwinn et al. (2010) which did not found evidence of a moderating effect of gender on the relationship between mental health and substance use. This study has several limitations. Mainly, the cross-sectional design prevents from inferring causal relationships. Longitudinal studies are needed to clarify the causal relationships between borderline and schizotypal traits and problematic use. The relationships suggested by our study could be considered as support for potential pathways to be further explored in longitudinal studies. However, this study suggests the importance of evaluating borderline and schizotypal traits, in studies of risk factors or consequences of cannabis use. Role of funding sources This study received no funding. Contributors Patrick Raynal and Henri Chabrol designed the study and conducted the statistical analyses. Henri Chabrol wrote the first draft of the manuscript and both authors contributed to and have approved the final manuscript. Declaration of interest The authors report no conflicts of interest.
References Andresen, E. M., Malmgren, J. A., Carter, W. B., & Patrick, D. L. (1994). Screening for depression in well older adults: Evaluation of a short form of the CES-D. American Journal of Preventive Medicine, 10, 77–84. Anglin, D. M., Corcoran, C. M., Brown, A. S., Chen, H., Lighty, Q., Brook, J. S., & Cohen, P. R. (2012). Early cannabis use and schizotypal personality disorder symptoms from adolescence to middle adulthood. Schizophrenia Research, 137, 45–49. http://dx.doi. org/10.1016/j.schres.2012.01.019. Annaheim, B., Rehm, J., & Gmel, G. (2008). How to screen for problematic cannabis use in population surveys. An evaluation of the Cannabis Use Disorders Identification Test (CUDIT) in a Swiss sample of adolescents and young adults. European Addiction Research, 14, 190–197. http://dx.doi.org/10.1159/000141643. Bouvard, M. (2002). Questionnaires et échelles d'évaluation de la personnalité [Questionnaires and scales assessing personality]. Paris: Masson. Chabrol, H., Ducongé, H., Casas, C., Roura, C., & Carey, K. (2005). Relations between cannabis use and dependence, motives for cannabis use and anxious, depressive and borderline symptomatology. Addictive Behaviors, 30, 829–840. http://dx.doi.org/10. 1016/j.addbeh.2004.08.027. Chabrol, H., Melioli, T., & Goutaudier, N. (2015). Association between personality disorders traits and problematic cannabis use in adolescents. Substance Use & Misuse, 50, 552–556. http://dx.doi.org/10.3109/10826084.2014.984851. Cohen, A. S., Buckner, J. D., Najolia, G. M., & Stewart, D. W. (2011). Cannabis and psychometrically-defined schizotypy: Use, problems and treatment considerations. Journal of Psychiatric Research, 45(4), 548–554. http://dx.doi.org/10.1016/j. jpsychires.2010.08.013. Cohen, P., Chen, H., Crawford, T. N., Brook, J. S., & Gordon, K. (2007). Personality disorders in early adolescence and the development of later substance use in the general population. Drug and Alcohol Dependence, 88, S71–S84 (doi: 10.1016%2Fj.drugalcdep. 2006.12.012). Dumas, P., Saoud, M., Bouafia, S., Gutknecht, C., Ecochard, R., Daléry, J., ... d'Amato, T. (2002). Cannabis use correlates with schizotypal personality traits in healthy students. Psychiatry Research, 109(1), 27–35. http://dx.doi.org/10.1016/S01651781(01)00358-4. Ferdinand, R. F., Sondeijker, F., Van Der Ende, J., Selten, J. P., Huizink, A., & Verhulst, F. C. (2005). Cannabis use predicts future psychotic symptoms, and vice versa. Addiction, 100(5), 612–618. http://dx.doi.org/10.1111/j.1360-0443.2005.01070.x. Fonseca-Pedrero, E., Lemos-Giráldez, S., Paino, M., Sierra-Baigrie, S., & Muñiz, J. (2012). Relationship between schizotypal and borderline traits in college students. The Spanish Journal of Psychology, 15(01), 306–314. http://dx.doi.org/10.5209/rev_SJOP. 2012.v15.n1.37337. Fonseca-Pedrero, E., Paino-Pineiro, M., Lemos-Giraldez, S., Villazon-Garcia, U., & Muniz, J. (2009). Validation of the Schizotypal Personality Questionnaire-Brief Form in adolescents. Schizophrenia Research, 111, 53–60. http://dx.doi.org/10.1016/j.schres.2009.03. 006. Guillem, E., Notides, C., Debray, M., Vorspan, F., Musa, C., Nieto, I., ... Lépine, J. P. (2011). Psychometric properties of the Cannabis Use Disorders Identification Test in French
P. Raynal, H. Chabrol / Addictive Behaviors 60 (2016) 144–147 cannabis misusers. Journal of Addictions Nursing, 22, 1–8. http://dx.doi.org/10.3109/ 10884602.2011.616604. Hyler, S. E. (1994). Personality Diagnostic Questionnaire (PDQ-4+). New York: New York State Psychiatric Institute. McGrath, J., Welham, J., Scott, J., Varghese, D., Degenhardt, L., Hayatbakhsh, M. R., ... Najman, J. M. (2010). Association between cannabis use and psychosis-related outcomes using sibling pair analysis in a cohort of young adults. Archives of General Psychiatry, 67(5), 440–447. http://dx.doi.org/10.1001/archgenpsychiatry.2010.6. Schiffman, J., Nakamura, B., Earleywine, M., & LaBrie, J. (2005). Symptoms of schizotypy precede cannabis use. Psychiatry Research, 134(1), 37–42. http://dx.doi.org/10.1016/ j.psychres.2005.01.004.
147
Schwinn, T. M., Schinke, S. P., & Trent, D. N. (2010). Substance use among late adolescent urban youths: Mental health and gender influences. Addictive Behaviors, 35(1), 30–34. http://dx.doi.org/10.1016/j.addbeh.2009.08.005. Skosnik, P. D., Spatz-Glenn, L., & Park, S. (2001). Cannabis use is associated with schizotypy and attentional disinhibition. Schizophrenia Research, 48(1), 83–92. http://dx.doi.org/10.1016/S0920-9964(00)00132-8. Williams, J. H., Wellman, N. A., & Rawlins, J. N. P. (1996). Cannabis use correlates with schizotypy in healthy people. Addiction, 91(6), 869–877. http://dx.doi.org/10.1046/j. 1360-0443.1996.91686912.x.