Exploring the Link between ADHD and Cannabis Use in Swedish Ninth Graders: The Role of Conduct Problems and Sensation-Seeking

Unhealthy behaviors associated with mental health disorders: a systematic comparative review of diet quality, sedentary behavior, and cannabis and tobacco use

Background

There are well-established literatures documenting the associations between mental disorders and unhealthy behaviors such as poor diet quality, sedentary behavior, and cannabis and tobacco use. Few studies have attempted to understand the respective findings in light of each other, however.

Objective

The purpose of this review was to assemble comparable data for each behavior-disorder association and assess the associations in terms of their overall strength. The review aimed to include a representative, but not exhaustive, range of studies that would allow for explorative comparisons.

Methods

Eligible studies were identified via Pubmed searches and citation searching, restricted to publications no older than 2015 written in English. To obtain comparable data, only studies that reported findings as odds ratios were included, and risk of bias related to study samples, behavioral measurement disparities, and control variables was assessed via sensitivity analyses. Findings for each disorder were compared on the basis of different measures of central tendency.

Results

From 3,682 records, 294 studies were included. The review found evidence of associations between each of the four unhealthy behaviors and psychosis, depression, anxiety, bipolar disorder, attention-deficit/hyperactivity disorder (ADHD), and post-traumatic stress disorder (PTSD), while personality disorder was only investigated in relation to cannabis and tobacco use. In overall comparison, the associations were generally of similar strength, and only the association between cannabis use and personality disorder was exceptional in terms of being significantly stronger than its counterparts across disorders and across behaviors. Analyses of bias risk identified some influence from behavioral measurement disparities and lack of adequate statistical control, but findings were generally robust across a range of sensitivity analyses.

Conclusion

This explorative and comparative review found that poor diet quality, sedentary behavior, and cannabis and tobacco use are about equally strongly associated with a range of different mental disorders. Given the general nature of these associations, we should probably understand them to reflect a general and shared etiology. However, the findings in this review should be regarded as tentative until confirmed by more comprehensive investigations.

Is there a gender paradox in the association between conduct problems and cannabis use? A cohort-study among Swedish adolescents

INTRODUCTION

Conduct problems (CP) predict cannabis use prospectively but the research is mixed as to whether this association is stronger among girls. A stronger association among girls would suggest a 'gender paradox' as both CP and cannabis use is less common in this group. This study aimed to assess whether the longitudinal association between CP and cannabis use in Swedish adolescents is stronger among girls.

METHODS

Data from two waves of a nationally representative cohort study of Swedish adolescents born in 2001 were used. Baseline measurements were collected in 9th grade (at age 15-16) and follow-up measures at 11th grade (at age 17-18).

RESULTS

CP at baseline were significantly associated with cannabis use at follow-up adjusted for hyperactivity problems, emotional problems, socio-demographics, parental monitoring, school grades and truancy at baseline (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.06-1.24) but not when also adjusting for substance use at baseline. Boys were more likely to have used cannabis during the past year, even when controlling for prior substance use (OR 2.29, 95% CI 1.76-2.98). The association between CP and cannabis use was significantly weaker for boys (OR 0.83, 95% CI 0.72-0.95 in the fully adjusted model). The predicted probability of cannabis use was stable at 0.13 for boys across levels of CP, but ranged from 0.05 to 0.16 for girls.

DISCUSSION AND CONCLUSION

The longitudinal association between CP and cannabis use was stronger among girls. The findings are indicative of a 'gender paradox' in the association between CP and cannabis use.