It has not yet been determined if the commonly reported cannabis–psychosis association is limited to individuals with pre-existing genetic risk for psychotic disorders.

We examined whether the relationship between polygenic risk score for schizophrenia (PRS-Sz) and psychotic-like experiences (PLEs), as measured by the Community Assessment of Psychic Experiences-42 (CAPE-42) questionnaire, is mediated or moderated by lifetime cannabis use at 16 years of age in 1740 of the individuals of the European IMAGEN cohort. Secondary analysis examined the relationships between lifetime cannabis use, PRS-Sz and the various sub-scales of the CAPE-42. Sensitivity analyses including covariates, including a PRS for cannabis use, were conducted and results were replicated using data from 1223 individuals in the Dutch Utrecht cannabis cohort.

PRS-Sz significantly predicted cannabis use (p = 0.027) and PLE (p = 0.004) in the IMAGEN cohort. In the full model, considering PRS-Sz and covariates, cannabis use was also significantly associated with PLE in IMAGEN (p = 0.007). Results remained consistent in the Utrecht cohort and through sensitivity analyses. Nevertheless, there was no evidence of a mediation or moderation effects.

These results suggest that cannabis use remains a risk factor for PLEs, over and above genetic vulnerability for schizophrenia. This research does not support the notion that the cannabis–psychosis link is limited to individuals who are genetically predisposed to psychosis and suggests a need for research focusing on cannabis-related processes in psychosis that cannot be explained by genetic vulnerability.

Although neuroimaging studies suggest brain regional abnormalities in depressive disorders, it remains unclear whether abnormalities are present at illness onset or reflect disease progression.

We hypothesized that cerebral variations were present in adolescents with subthreshold depression known to be at high risk for later full-blown depression.

We examined brain structural and diffusion-weighted magnetic resonance images of adolescents with subthreshold depression.

The participants were extracted from the European IMAGEN study cohort of healthy adolescents recruited at age 14. Subthreshold depression was defined as a distinct period of abnormally depressed or irritable mood, or loss of interest, plus two or more depressive symptoms but without diagnosis of Major Depressive Episode. Comparisons were performed between adolescents meeting these criteria and control adolescents within the T1-weighted imaging modality (118 and 475 adolescents respectively) using voxel-based morphometry and the diffusion tensor imaging modality (89 ad 422 adolescents respectively) using tract-based spatial statistics. Whole brain analyses were performed with a statistical threshold set to p< 0.05 corrected for multiple comparisons.

Compared with controls, adolescents with subthreshold depression had smaller gray matter volume in caudate nuclei, medial frontal and cingulate cortices; smaller white matter volume in anterior limb of internal capsules, left forceps minor and right cingulum; and lower fractional anisotropy and higher radial diffusivity in the genu of corpus callosum.

The findings suggest that adolescents with subthreshold depression have volumetric and microstructural gray and white matter changes in the emotion regulation frontal-striatal-limbic network.

No existing models of alcohol prevention concurrently adopt universal and selective approaches. This study aims to evaluate the first combined universal and selective approach to alcohol prevention.

A total of 26 Australian schools with 2190 students (mean age: 13.3 years) were randomized to receive: universal prevention (Climate Schools); selective prevention (Preventure); combined prevention (Climate Schools and Preventure; CAP); or health education as usual (control). Primary outcomes were alcohol use, binge drinking and alcohol-related harms at 6, 12 and 24 months.

Climate, Preventure and CAP students demonstrated significantly lower growth in their likelihood to drink and binge drink, relative to controls over 24 months. Preventure students displayed significantly lower growth in their likelihood to experience alcohol harms, relative to controls. While adolescents in both the CAP and Climate groups demonstrated slower growth in drinking compared with adolescents in the control group over the 2-year study period, CAP adolescents demonstrated faster growth in drinking compared with Climate adolescents.

Findings support universal, selective and combined approaches to alcohol prevention. Particularly novel are the findings of no advantage of the combined approach over universal or selective prevention alone.

Most empirical studies into the covariance structure of psychopathology have been confined to adults. This work is not developmentally informed as the meaning, age-of-onset, persistence and expression of disorders differ across the lifespan. This study investigates the underlying structure of adolescent psychopathology and associations between the psychopathological dimensions and sex and personality risk profiles for substance misuse and mental health problems.

This study analyzed data from 2175 adolescents aged 13.3 years. Five dimensional models were tested using confirmatory factor analysis and the external validity was examined using a multiple-indicators multiple-causes model.

A modified bifactor model, with three correlated specific factors (internalizing, externalizing, thought disorder) and one general psychopathology factor, provided the best fit to the data. Females reported higher mean levels of internalizing, and males reported higher mean levels of externalizing. No significant sex differences emerged in liability to thought disorder or general psychopathology. Liability to internalizing, externalizing, thought disorder and general psychopathology was characterized by a number of differences in personality profiles.

This study is the first to identify a bifactor model including a specific thought disorder factor. The findings highlight the utility of transdiagnostic treatment approaches and the importance of restructuring psychopathology in an empirically based manner.

Resilience is the capacity of individuals to resist mental disorders despite exposure to stress. Little is known about its neural underpinnings. The putative variation of white-matter microstructure with resilience in adolescence, a critical period for brain maturation and onset of high-prevalence mental disorders, has not been assessed by diffusion tensor imaging (DTI). Lower fractional anisotropy (FA) though, has been reported in the corpus callosum (CC), the brain's largest white-matter structure, in psychiatric and stress-related conditions. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents.

Three groups of adolescents recruited from the community were compared: resilient with low risk of mental disorder despite high exposure to lifetime stress (n = 55), at-risk of mental disorder exposed to the same level of stress (n = 68), and controls (n = 123). Personality was assessed by the NEO-Five Factor Inventory (NEO-FFI). Voxelwise statistics of DTI values in CC were obtained using tract-based spatial statistics. Regional projections were identified by probabilistic tractography.

Higher FA values were detected in the anterior CC of resilient compared to both non-resilient and control adolescents. FA values varied according to resilience capacity. Seed regional changes in anterior CC projected onto anterior cingulate and frontal cortex. Neuroticism and three other NEO-FFI factor scores differentiated non-resilient participants from the other two groups.

High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk was associated with personality characteristics. Resilience in adolescence may be related to white-matter microstructure.

Using longitudinal and prospective measures of psychotic experiences during adolescence, we assessed the risk of developing psychosis in three groups showing low, increasing and elevated psychotic experiences associated with bullying by peers and cannabis use in a UK sample of adolescents.

Data were collected by self-report from 1098 adolescents (mean age 13.6 years; 60.9% boys) at five separate time points, equally separated by 6 months, across a 24-month period. General growth mixture modelling identified three distinct trajectories of adolescents reporting psychotic experiences: elevated, increasing and low.

Controlling for cannabis use, bullying by peers significantly predicted change in psychotic experiences between Time 2 and Time 5 in adolescents belonging to the increasing group. No effect was found for the elevated or low groups. Controlling for bullying, an earlier age of cannabis use and cannabis use more than twice significantly predicted change in psychotic experiences in adolescents belonging to the increasing group. Cannabis use at any age was significantly associated with subsequent change in psychotic experiences in the low group. Reverse causal associations were examined and there was no evidence for psychotic experiences at Time 1 predicting a subsequent change in cannabis use between Times 2 and 5 in any trajectory group.

Bullying by peers and cannabis use are associated with adolescents' reports of increasing psychotic experiences over time. Further research into the longitudinal development of psychosis in adolescence and the associated risk factors would allow for early intervention programmes to be targeted more precisely.

Research suggests that psychotic-like experiences (PLEs) in the general population are common, but can reflect either transitory or persistent developmental phenomena. Using a general adolescent population it was examined whether different developmental subtypes of PLEs exist and whether different trajectories of PLEs are associated with certain environmental risk factors, such as victimization and substance use.

Self-reported PLEs were collected from 409 adolescents (mean age 14 years 7 months) at four time points, each 6 months apart. General growth mixture modelling was utilized to identify classes of adolescents who followed distinct trajectories of PLEs across this period. Predictors of class membership included demographics, personality, victimization, depression, anxiety and substance use.

We identified the following three developmental subgroups of PLEs: (1) persistent; (2) increasing; (3) low. Adolescents on the persistent trajectory reported frequent victimization and consistent elevated scores in depression and anxiety. Adolescents on the increasing trajectory were engaging in cigarette use prior to any increases in PLEs and were engaging in cocaine, cannabis and other drug use as PLEs increased at later time points.

The findings suggest that different developmental subgroups of PLEs exist in adolescence and are differentially related to victimization and substance use.