It is not clear to what extent associations between schizophrenia, cannabis use and cigarette use are due to a shared genetic etiology. We, therefore, examined whether schizophrenia genetic risk associates with longitudinal patterns of cigarette and cannabis use in adolescence and mediating pathways for any association to inform potential reduction strategies.

Associations between schizophrenia polygenic scores and longitudinal latent classes of cigarette and cannabis use from ages 14 to 19 years were investigated in up to 3925 individuals in the Avon Longitudinal Study of Parents and Children. Mediation models were estimated to assess the potential mediating effects of a range of cognitive, emotional, and behavioral phenotypes.

The schizophrenia polygenic score, based on single nucleotide polymorphisms meeting a training-set p threshold of 0.05, was associated with late-onset cannabis use (OR = 1.23; 95% CI = 1.08,1.41), but not with cigarette or early-onset cannabis use classes. This association was not mediated through lower IQ, victimization, emotional difficulties, antisocial behavior, impulsivity, or poorer social relationships during childhood. Sensitivity analyses adjusting for genetic liability to cannabis or cigarette use, using polygenic scores excluding the CHRNA5-A3-B4 gene cluster, or basing scores on a 0.5 training-set p threshold, provided results consistent with our main analyses.

Our study provides evidence that genetic risk for schizophrenia is associated with patterns of cannabis use during adolescence. Investigation of pathways other than the cognitive, emotional, and behavioral phenotypes examined here is required to identify modifiable targets to reduce the public health burden of cannabis use in the population.

22q11.2 deletion syndrome (22q11.2DS) is associated with high rates of neurodevelopmental disorder, however, the links between developmental coordination disorder (DCD), intellectual function and psychiatric disorder remain unexplored.

To establish the prevalence of indicative DCD in children with 22q11.2DS and examine associations with IQ, neurocognition and psychopathology.

Neurocognitive assessments and psychiatric interviews of 70 children with 22q11.2DS (mean age 11.2, s.d. = 2.2) and 32 control siblings (mean age 11.5, s.d. = 2.1) were carried out in their homes. Nine children with 22q11.2DS and indicative DCD were subsequently assessed in an occupational therapy clinic.

Indicative DCD was found in 57 (81.4%) children with 22q11.2DS compared with 2 (6.3%) control siblings (odds ratio (OR) = 36.7, P < 0.001). Eight of nine (89%) children with indicative DCD met DSM-5 criteria for DCD. Poorer coordination was associated with increased numbers of anxiety, (P < 0.001), attention-deficit hyperactivity disorder (ADHD) (P < 0.001) and autism-spectrum disorder (ASD) symptoms (P < 0.001) in children with 22q11.2DS. Furthermore, 100% of children with 22q11.2DS and ADHD had indicative DCD (20 of 20), as did 90% of children with anxiety disorder (17 of 19) and 96% of children who screened positive for ASD (22 of 23). The Developmental Coordination Disorder Questionnaire score was related to sustained attention (P = 0.006), even after history of epileptic fits (P = 0.006) and heart problems (P = 0.009) was taken into account.

Clinicians should be aware of the high risk of coordination difficulties in children with 22q11.2DS and its association with risk of mental disorder and specific neurocognitive deficits.

None.