Background: Attention-deficit/hyperactivity disorder (ADHD) frequently co-occurs with other psychiatric disorders. Twin studies have established that these co-occurrences are in part due to shared genetic risks. However, the strength of these genetic overlaps and the potential heterogeneity accounted for by type of psychiatric symptoms, age, and methods of assessment remain unclear. We conducted a systematic review to fill this gap. Methods: We searched PubMed, PsycINFO, Embase, and Web of Science until March 07, 2019. Genetic correlations (r g) were used as effect size measures. Results: A total of 31 independent studies fulfilled the inclusion criteria. The pooled estimates showed that the associations between ADHD and other psychiatric symptoms were partly explained by shared genetic factors, with a pooled genetic correlation of 0.50, 95% confidence interval: 0.46-0.60. The genetic correlations (r g) between ADHD and externalizing (r g = .49 [0.37-0.61]), internalizing (r g = .50 [0.39-0.69]), and neurodevelopmental (r g = .56 [0.47-0.66]) symptoms were similar in magnitude. The genetic correlations in childhood and adulthood were r g = .53 (0.43-0.63) and r g = .51 (0.44-0.56), respectively. For methods of assessment, the genetic correlations were also similar in strength, self-reports r g = .52 (0.47-0.58), other informants r g = .55 (0.41-0.69), and combined raters r g = .50 (0.33-0.65). Conclusions: These findings indicate that the cooccurrence of externalizing, internalizing, and neurodevelopmental disorder symptoms in individuals with ADHD symptoms in part is due to a shared genetic risk.

Background Low resting heart rate (RHR) and low systolic blood pressure (SBP) are associated with criminal behavior. However, knowledge is lacking about their predictive value for reoffending. Aim We aimed to examine associations of RHR and SBP with reoffending in a large population-based sample. Methods We conducted a cohort study of all convicted male conscripts born in Sweden 1958–1990 (N = 407,533). We obtained data by linking Swedish population-based registers. Predictor variables were RHR and SBP, measured at conscription which was mandatory until 2010 for men at age 18. The outcome variable was reoffending, defined as criminal convictions (any crime, violent crime and non-violent crime), obtained from the National Crime Register. We used survival analyses to test for associations of RHR and SBP with reoffending, adjusting for pertinent covariates such as socioeconomic status, height, weight and physical energy capacity. Results In fully adjusted Cox regression models, men with lower RHR (≤60 bpm) had higher risk of reoffending (any crime: HR = 1.17, 95% CI: 1.14, 1.19, violent crime: HR = 1.23, 95% CI: 1.17, 1.29, non-violent crime: HR = 1.16, 95% CI: 1.14, 1.19), compared to men with higher RHR (≥ 82 bpm). Men with lower SBP (≤80 mmHg) had higher risk of reoffending (any crime: HR = 1.19, 95% CI: 1.17, 1.21, violent crime: HR = 1.16, 95% CI: 1.12, 1.20, non-violent crime: HR = 1.20, 95% CI: 1.18, 1.22), compared to men with higher SBP (≥138 mmHg). Conclusions Low autonomic arousal is associated with increased risk of reoffending. RHR and SBP should be investigated further as potential predictors for reoffending as they each may have predictive value in risk assessment protocols.

Background Attention-deficit/hyperactivity disorder (ADHD) has been associated with an increased risk of tobacco smoking, and more difficulties with smoking cessation compared to non-ADHD individuals. Women with ADHD may therefore show elevated rates of smoking during pregnancy. Aims To examine the association between ADHD and smoking habits among pregnant women in Sweden and Norway. Methods Women pregnant for the first time were identified in Sweden (n = 622,037), and Norway (n = 293,383), of which 1.2% (n = 7,444), and 1.7% (n = 4,951) were defined as having ADHD, respectively. Data on smoking habits were collected early and late in pregnancy. Results In Sweden, ADHD was associated with an increased risk of smoking early in pregnancy, adjusted risk ratio (adjRR) 2.69 (95% confidence interval, 2.58-2.81), and late in pregnancy, adjRR 2.95 (2.80-3.10). Similar findings were observed in the Norwegian data, early in pregnancy, adjRR 2.31 (2.21-2.40), and late in pregnancy, adjRR 2.56 (2.42-2.70).

BACKGROUND AND OBJECTIVES: Attention-deficit/hyperactivity disorder (ADHD) and obesity are 2 frequent conditions that co-occur, which has implications for the management of both conditions. We hypothesized that ADHD symptoms predict BMI and vice versa from late childhood (10–12 years) up to early adulthood (20–22 years). METHODS: Participants were adolescents in the Netherlands (n = 2773, 52.5% male, mean age = 11 years at baseline, 5 waves up to mean age 22) from the Tracking Adolescents’ Individual Lives Survey cohort. We examined bidirectional relationship between ADHD symptoms (hyperactivity/impulsivity and inattention) and BMI using the random intercept cross-lagged panel model. Time-varying covariates were pubertal status, stimulant use, depressive symptoms, and family functioning, and socioeconomic status was a time-invariant covariate. RESULTS: We found a time-invariant association of BMI with hyperactivity and impulsivity, but not with inattention, which was slightly stronger in female adolescents (female: r = 0.102; male: r = 0.086, P < .05). No longitudinal direct effects were found between ADHD symptoms and BMI during this period. CONCLUSIONS: Over the course of adolescence, the link between ADHD and BMI is stable and is predominantly with hyperactive and impulsive symptoms rather than inattention. There was no direct effect of ADHD symptoms on BMI increase nor of BMI on enhanced ADHD symptoms during this developmental period. The findings point to a shared genetic or familial background and/or potential causal effects established already earlier in childhood, thus suggesting that intervention and prevention programs targeting overweight and obesity in children with ADHD should be implemented in early childhood.

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