Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

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Objective This study examined the relationship between leukocyte telomere length (LTL), a marker of cell aging, and psychiatric disorders in adults compared to controls using meta-analytic methods. Methods Data were abstracted from studies examining the relationship between LTL and adult psychiatric disorders. In addition to an overall estimate of effect size, subgroup analyses and meta-regression were performed to examine whether covariates (including psychiatric diagnoses) moderated the estimate. Results A significant overall effect size showing LTL shortening was found across all psychiatric disorders (Hedge’s g = −0.50, p< 0.001). Subgroup analyses did not demonstrate significant differences in effect size based on individual covariates (psychiatric disorder, sex, age or assay method). The meta-regression indicated that although type of disorder and, likely, age moderate the overall effect size, the heterogeneity between studies could be explained by a model that included these variables as well as sex and assay method. Although not significantly different, post-traumatic stress disorder, anxiety disorders and depressive disorders had comparatively larger effect sizes (−1.27, −.53, and −.55), and psychotic and bipolar disorders had comparatively smaller ones (−.23 and −.26). Conclusions We observed a robust effect size of LTL shortening for psychiatric disorders as a whole compared to controls. The results were less straightforward regarding relative differences in the strength of this association by specific disorder. Future studies should focus on mechanisms explaining accelerated cell aging with psychiatric illness, defining directions (if any) of causality and elucidating possible differences in this association between disorders.

SUMMARY Tourette syndrome (TS) is a model neuropsychiatric disorder thought to arise from abnormal development and/or maintenance of cortico-striato-thalamo-cortical circuits. TS is highly heritable, but its underlying genetic causes are still elusive, and no genome-wide significant loci have been discovered to date. We analyzed a European ancestry sample of 2,434 TS cases and 4,093 ancestry-matched controls for rare (<1% frequency) copy-number variants (CNVs) using SNP microarray data. We observed an enrichment of global CNV burden that was prominent for large (>1 Mb), singleton events (OR=2.28, 95%CI [1.39–3.79], p=1.2×10−3) and known, pathogenic CNVs (OR=3.03 [1.85–5.07], p=1.5×10−5). We also identified two individual, genome-wide significant loci, each conferring a substantial increase in TS risk (NRXN1 deletions, OR=20.3, 95%CI [2.6–156.2]; CNTN6 duplications, OR=10.1, 95% CI [2.3–45.4]). Approximately 1% of TS cases carry one of these CNVs, indicating that rare structural variation contributes significantly to the genetic architecture of TS.

Introduction This study examined effects of experimentally manipulated social media exposure on adolescents’ willingness and intention to use e-cigarettes. Methods Participants were 135 adolescents age 13-18 (52.6% female, M age=15.3) in California. Participants viewed 6 social media posts online in a 2 (post source: peer or advertisement) X 2 (e-cigarette content exposure: heavy or light) between-subjects design. Analyses were weighted to population benchmarks. We examined adolescents’ beliefs, willingness, and intention to use e-cigarettes in association with social media use intensity in daily life and with experimentally manipulated exposure to social media posts that varied by source (peer or advertisement) and content (e-cigarette heavy or light). Results Greater social media use in daily life was associated with greater willingness and intention to use e-cigarettes and more positive attitudes, greater perceived norms, and lower perceived danger of e-cigarette use (all p-values&lt;.01). In tests of the experimental exposures, heavy (versus light) e-cigarette content resulted in greater intention (p=.049) to use e-cigarettes and more positive attitudes (p=.019). Viewing advertisements (versus peer-generated posts) resulted in greater willingness and intention (p-values&lt;.01) to use e-cigarettes, more positive attitudes (p=.003), and greater norm perceptions (p=.009). The interaction effect of post source by post content was not significant for any of the outcomes (all p-values&gt;0.529) Conclusions Greater social media use and heavier exposure to advertisements and e-cigarette content in social media posts are associated with a greater risk for e-cigarette use among adolescents. Regulatory action is needed to prohibit sponsored e-cigarette content on social media platforms used by youth.

Objective Tourette syndrome (TS) and autism spectrum disorder (ASD) share clinical features and possibly an overlapping etiology. This study: 1) examined ASD symptom rates in participants with TS and 2) characterized the relationships between ASD symptom patterns and TS, obsessive-compulsive disorder (OCD), and attention-deficit/hyperactivity disorder (ADHD). Method Participants with TS (n = 535) and their family members (n =234) recruited for genetic studies reported TS, OCD, and ADHD symptoms and completed the Social Responsiveness Scale Second Edition (SRS), which was used to characterize ASD symptoms. Results SRS scores in participants with TS were similar to those observed in other clinical samples but lower than in ASD samples (mean SRS total raw score = 51; SD=32.4). More children with TS met cut-off criteria for ASD (22.8%) than adults with TS (8.7%). The elevated rate in children was primarily due to high scores on the SRS Repetitive and Restricted Behaviors (RRB) subscale. Total SRS scores were correlated with TS (r=0.27), OCD (r=0.37), and ADHD (r=0.44) and were higher among individuals with OCD symptom-based phenotypes than for those with tics alone. Conclusion Higher observed rates of ASD among children affected by TS may in part be due to difficulty in discriminating complex tics and OCD symptoms from ASD symptoms. Careful examination of ASD-specific symptom patterns (social communication vs. repetitive behaviors) is essential. Independent of ASD, the SRS may be a useful tool for identifying patients with TS with impairments in social communication, potentially putting them at risk for bullying and other negative sequelae.

Objective Phenotypic heterogeneity in Tourette syndrome (TS) is partly due to complex genetic relationships between TS, obsessive-compulsive disorder (OCD) and attention deficit/hyperactivity disorder (ADHD). Identifying symptom-based endophenotypes across diagnoses may aid gene-finding efforts. Method 3494 individuals recruited for genetic studies were assessed for TS, OCD, and ADHD symptoms. Symptom-level factor and latent class analyses were conducted in TS families and replicated in an independent sample. Classes were characterized by comorbidity rates and proportion of parents. Heritability and TS-, OCD-, and ADHD-associated polygenic load were estimated. Results We identified two cross-disorder symptom-based phenotypes across analyses: symmetry (symmetry, evening up, checking obsessions; ordering, arranging, counting, writing-rewriting compulsions, repetitive writing tics) and disinhibition (uttering syllables/words, echolalia/palilalia, coprolalia/copropraxia and obsessive urges to offend/mutilate/be destructive). Heritability estimates for both endophenotypes were high (disinhibition factor= 0.35, SE=0.03, p= 4.2 ×10−34; symmetry factor= 0.39, SE=0.03, p= 7.2 ×10−31; symmetry class=0.38, SE=0.10, p=0.001). Mothers of TS probands had high rates of symmetry (49%) but not disinhibition (5%). Polygenic risk scores derived from a TS genome-wide association study (GWAS) were associated with symmetry (p= 0.02), while risk scores derived from an OCD GWAS were not. OCD polygenic risk scores were associated with disinhibition (p =0.03), while TS and ADHD risk scores were not. Conclusions We identified two heritable TS-related endophenotypes that cross traditional diagnostic boundaries. The symmetry phenotype correlated with TS polygenic load, and was present in otherwise “TS-unaffected” mothers, suggesting that this phenotype may reflect additional TS (rather than OCD) genetic liability that is not captured by traditional DSM-based diagnoses.

Symmetry/exactness, aggressive urges, fear-of-harm, and hoarding show complex genetic relationships with TS, OCD, and ADHD, and, rather than being specific subtypes of OCD, transcend traditional diagnostic boundaries, perhaps representing an underlying vulnerability (e.g. failure of top-down cognitive control) common to all three disorders.