Associations of externalizing polygenic scores with externalizing disorders among Mexican youth.

Several studies have examined the association of externalizing polygenic scores (PGS) with externalizing symptoms in samples of European ancestry. However, less is known about the associations of externalizing polygenic vulnerability in relation to phenotypic externalizing disorders among individuals of different ancestries, such as Mexican youth. Here, we leveraged the largest genome-wide association study on externalizing behaviors that included over 1 million individuals of European ancestry to examine associations of externalizing PGS with a range of externalizing disorders in Mexican adolescents, and investigated whether adversity exposure in childhood moderated these associations. Participants (N = 1064; age range 12-17 years old; 58.8% female) were adolescents recruited for a general population survey on adolescent mental health in the Mexico City Metropolitan region and were genotyped. Childhood adversity exposure and externalizing disorders, specifically attention-deficit hyperactivity disorder (ADHD), conduct disorder, oppositional defiant disorder, and substance use disorder, were assessed via the computer-assisted World Mental Health Composite International Diagnostic Interview for adolescents. A greater externalizing PGS was associated with a greater odds of any externalizing disorder (OR = 1.29 [1.12, 1.48]; p < 0.01) and ADHD (OR = 1.40 [1.15, 1.70]; p < 0.01) in the whole sample, and in females in particular. There were no main effects of the externalizing PGS on conduct disorder, oppositional defiant disorder, or substance use disorder, nor did adversity exposure moderate these associations. Our results suggest that greater genetic propensity for externalizing disorders is associated with increased odds of any externalizing disorders and ADHD among Mexican adolescents, furthering our understanding of externalizing disorder manifestation in this population.

Cathechol-O-methyltransferase Val(158)Met polymorphism is associated with disruptive behavior disorders among children and adolescents with ADHD.

COMT Val(158)Met polymorphism has been associated with both symptoms of attention-deficit/hyperactivity disorder (ADHD) and disruptive behavior disorders (DBD): that is, oppositional defiant disorder (ODD) and conduct disorder (CD) often comorbid with ADHD. The aim of this study was to test the association between COMT Val(158)Met polymorphism and the presence of DBD in children with ADHD (n = 516). Homozygous Val/Val children showed a higher prevalence of ADHD comorbid with DBD (χ(2) = 5.762; p = 0.016; OR = 1.58; CI(95%) = 1.07-2.35). Our findings replicate previous results and suggest a role for COMT in the etiology of DBD in children and adolescents with ADHD.

Migration from Mexico to the United States and conduct disorder: a cross-national study.

CONTEXT: Twin studies suggest that conduct disorder (CD) is under substantial genetic influence, which is stronger for aggressive than for nonaggressive symptoms. Studies of migrating populations offer an alternative strategy for separating environmental and genetic influences on psychiatric disorders. OBJECTIVES: To examine variation in the prevalence of CD associated with migration from Mexico to the United States and to determine whether this variation is similar for aggressive and nonaggressive CD symptoms and symptom profiles. DESIGN: The prevalences of CD, different types of CD symptoms, and CD symptom profiles were compared across 3 generations of people of Mexican origin with increasing levels of exposure to American culture: families of origin of migrants (residing in Mexico), children of Mexican migrants raised in the United States, and Mexican-American children of US-born parents. SETTING: General population surveys conducted in Mexico and the United States using the same diagnostic interview. PARTICIPANTS: Adults aged 18 to 44 years in the household population of Mexico and the household population of people of Mexican descent in the United States. MAIN OUTCOME MEASURES: Conduct disorder criteria, assessed using the World Mental Health version of the Composite International Diagnostic Interview. RESULTS: Compared with the risk in families of origin of migrants, risk of CD was lower in the general population of Mexico (odds ratio [OR], 0.54; 95% CI, 0.19-1.51), higher in children of Mexican-born immigrants who were raised in the United States (OR, 4.12; 95% CI, 1.47-11.52), and higher still in Mexican-American children of US-born parents (OR, 7.64; 95% CI, 3.20-18.27). The association with migration was markedly weaker for aggressive than for nonaggressive symptoms. CONCLUSIONS: The prevalence of CD increases dramatically across generations of the Mexican-origin population after migration to the United States. This increase is of larger magnitude for nonaggressive than for aggressive symptoms, consistent with the suggestion that nonaggressive symptoms are more strongly influenced by environmental factors than are aggressive symptoms.