To Örebro University

Background: Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder characterized by impaired attention and hyperactivity/impulsivity. ADHD is associated with several comorbidities and health-related outcomes. However, it is uncertain whether ADHD is more strongly associated with certain disorder domains, and whether ADHD-related comorbidities and health-related outcomes is important to consider during pregnancy. 

Aims: To expand the knowledge regarding the genetic overlap between ADHD and other psychiatric disorder symptoms, and to increase the awareness and understanding related to ADHD in women, with a focus on adverse health behaviors, mental health problems, and pregnancy outcomes. 

Methods: The present thesis includes one systematic review and metaanalysis (Study I), and three studies based on population-based register data from Sweden (Study II, III, and IV), and Norway (Study II).

Results: Individuals with ADHD have an increased liability to meet criteria for externalizing, internalizing and neurodevelopmental disordersymptoms, and these co-occurrences are partly due to shared genetic risks. Further, ADHD is an important risk factor to consider before, during and after pregnancy, as ADHD increases the risk of smoking during pregnancy, mental health problems postpartum, and adverse pregnancy outcomes.

Conclusions: The genetic overlaps between ADHD and other psychiatric disorder symptoms were similar across disorder dimensions. Further, results demonstrated that ADHD is an important risk factor to consider in women surrounding pregnancy. These findings point towards the importance of recognizing that women diagnosed with ADHD need to be prioritized and allowed more attention and support by the healthcare system, specifically during their fertile years. 

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is associated with an increased risk of poor mental health. However, the understanding of ADHD-related burden and impairments in women during the postpartum period is limited. The aim with the present study was to examine the risk of depression and anxiety disorders during the postpartum period among women with and without an ADHD diagnosis.

METHODS: We used register-based data to identify women who gave birth to their first and/or second child between 2005 and 2013 in Sweden (n = 773,047), of which 0.5 % (n = 3515) had a diagnosis of ADHD prior to pregnancy. Diagnoses of depression and anxiety disorders up to one year after delivery were collected from the national patient register.

RESULTS: A total of 16.76 % of the women with an ADHD diagnosis were also diagnosed with depression disorders in the postpartum period, prevalence ratio (PR) 5.09 (95 % confidence interval (CI), 4.68-5.54). A total of 24.92 % of the women with an ADHD diagnosis were also diagnosed with anxiety disorders in the postpartum period, PR 5.41 (5.06-5.78). Stratified results revealed that having a diagnosis of ADHD increased the risk for both depression and anxiety disorders postpartum, beyond other well-known risk factors.

LIMITATIONS: There is a potential risk of surveillance bias as women diagnosed with ADHD are more likely to have repeated visits to psychiatric care and might have an enhanced likelihood of also being diagnosed with depression and anxiety disorders postpartum, compared to women without ADHD.

CONCLUSIONS: ADHD is an important risk factor for both depression and anxiety disorders postpartum. Therefore, ADHD needs to be considered in the maternal care, regardless of sociodemographic factors and the presence of other psychiatric disorders.

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). Women with ADHD were more likely to continue smoking during pregnancy, compared to women without ADHD, both in Sweden adjRR 1.13 (1.10-1.17), and in Norway, adjRR 1.16 (1.12-1.20). Having a sibling diagnosed with ADHD was associated with an increased risk of smoking early and late in pregnancy, in both Sweden and Norway.

Conclusions: Women with ADHD are considerably more likely to smoke early and late in (their first) pregnancy and are less likely to stop smoking between the two time points. Smoking, early and late in pregnancy, co-aggregates in families with ADHD. Smoking prevention and intervention programs should be targeted towards women with ADHD, specifically during their childbearing years, to ensure better mother and child outcomes.

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 werer(g) = .53 (0.43-0.63) andr(g) = .51 (0.44-0.56), respectively. For methods of assessment, the genetic correlations were also similar in strength, self-reportsr(g) = .52 (0.47-0.58), other informantsr(g) = .55 (0.41-0.69), and combined ratersr(g) = .50 (0.33-0.65).

Conclusions: These findings indicate that the co-occurrence of externalizing, internalizing, and neurodevelopmental disorder symptoms in individuals with ADHD symptoms in part is due to a shared genetic risk.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder (Wilens, Biederman & Spencer 2002) and affects approximately 5% of children (Polanczyk, de Lima, Horta, Biederman & Rohde 2007). About half of those diagnosed in childhood continue to have the diagnosis and symptoms in adulthood (Kessler et al. 2006). The co-occurrence of ADHD with other psychiatric disorder symptoms (Burt et al. 2001; Cole et al. 2009; Polderman et al. 2014) has been suggested to be partly explained by a shared genetic vulnerability (Polderman et al. 2014). However, the strength of the genetic overlap is currently unclear. Also, no study has examined whether the genetic correlations differs between age groups (childhood versus adulthood), by rater (self-report, other informant, combined (parent-teacher, parent-twin, teacher-twin)), or by type of psychiatric disorder symptoms (externalizing, internalizing, neu-rodevelopmental). To address this gap, we conducted a systematic literature search to identify relevant twin studies, in PubMed, PsycINFO, and EMBASE. A total of 31 articles were identified and included in the present study. The pooled estimates showed that the comorbidity between ADHD and diverse psychiatric disorder symptoms were explained by shared genetic effectsrg= 0.50 (0.43–0.56). A similar shared genetic overlap between ADHD and psychiatric disorder symptoms was observed in both childhood rg= 0.51(0.42–0.61) and adulthood rg= 0.47 (0.40–0.53). Similar results werealso found for self-reports rg= 0.49 (0.42–0.55), other informants rg= 0.50 (0.40–0.60), and combined raters rg= 0.51 (0.30–0.69). Further, the strength of the genetic correlations of ADHD with the externalizing rg= 0.49 (0.39–0.59), internalizing rg= 0.55 (0.40–0.68) and neurodevelopmental rg= 0.47 (0.40–0.53) spectrums were similar in magnitude. These findings emphasize the presence of a shared genetic liability between ADHD and externalizing, internalizing and neurodevelopmental disorder symptoms, independent of age and rater.

References

Burt, S. A., Krueger, R. F., McGue, M., Iacono, W. G. (2001).Sources of covariation among attention-deficit/hyperactivity disorder,oppositional defiant disorder, and conduct disorder: the importance ofshared environment.Journal of Abnormal Psychology, 4, 516–525.

Cole, J., Ball, H. A., Martin, N. C., Scourfield, J., McGuffin, P.(2009). Genetic overlap between measures of hyperactivity/inatten-tion and mood in children and adolescents.J Am Acad Child AdolescPsychiatry48, 1094–1101.

Kessler, R. C., Adler, L., Barkley, R., Biederman, J., Conners, C.K., Demler, O., Faraone, S. V., Greenhill, L. L., Howes, M. J., Secnik,K., Spencer, T., Ustun, T. B., Walters, E. E., Zaslavsky, A. M. (2006).The prevalence and correlates of adult ADHD in the United States:results from the National Comorbidity Survey Replication.Am JPsychiatry, 163, 716–723.

Polanczyk, G., de Lima, M. S., Horta, B. L., Biederman, J., Rohde,L. A. (2007). The worldwide prevalence of ADHD: a systematicreview and metaregression analysis.Am J Psychiatry, 164, 942-8.

Polderman, T. J., Hoekstra, R. A., Posthuma, D., Larsson, H.(2014). The co-occurrence of autistic and ADHD dimensions inadults: an etiological study in 17,770 twins.Transl Psychiatry2014;4: e435.

Wilens, T. E., Biederman, J., Spencer, T. J. (2002). Attentiondeficit/hyperactivity disorder across the lifespan.Annual Review Med53:113–131.

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.

BACKGROUND: Lower autonomic arousal is a well-known correlate of criminal offending and other risk-taking behaviors in men, but few studies have investigated this association in women.

AIM: To test associations between autonomic arousal and criminal offending as well as unintentional injuries among female conscripts.

METHODS: All women born 1958-1994 in Sweden who participated in voluntary military conscription (n = 12,499) were identified by linking Swedish population-based registers. Predictors were resting heart rate (RHR) and systolic blood pressure (SBP). Covariates were height, weight, and physical energy capacity. Main outcomes were criminal convictions (any, violent, and non-violent) from the National Crime Register. Secondary outcome was unintentional injuries requiring medical treatment or causing death. We used survival analyses to test for associations between predictors and outcomes.

RESULTS: Low RHR, relative to high RHR, was associated with an increased risk of any criminal conviction, non-violent criminal convictions, and unintentional injuries. Low SBP, relative to high SBP, was associated with an increased risk of violent criminal convictions.

CONCLUSIONS: Results support lower autonomic arousal, particularly lower RHR, as a correlate of criminal offending among women that warrants further examination, as the reported findings have potential implications for the prediction of future female crime.

Lower resting heart rate and lower levels of empathy have independently been associated with an increased risk of antisocial behavior. However, little is known about the potential interaction between resting heart rate and empathy in predicting antisocial behavior. The aim of the current project was to examine the moderating role of empathy in young adulthood on the association between resting heart rate in childhood and antisocial behavior in young adulthood. We utilized two subsamples from the University of Southern California Risk Factors for Antisocial Behavior Project (n=707, n=616), a longitudinal project with data from five waves. Resting heart rate was measured using disposable electrodes attached to the torso. Empathy was measured using the Interpersonal Reactivity Index with four subscales. Antisocial behavior was defined as law enforcement involvement. After adjusting for potential confounds, results suggest that lower resting heart rate in childhood and lower empathy in young adulthood predict antisocial behavior in young adulthood. Most importantly, empathy in young adulthood moderated the association between resting heart rate in childhood and antisocial behavior in young adulthood. Results indicate that at lower levels of empathy, a lower resting heart rate was associated with increased probability of being in trouble with the police.

Biopsychosocial criminological theories suggest that it is important to consider interactions between risk factors from different domains in the prediction of externalizing behavior. Lower resting heart rate is considered the best replicated biological risk factor for externalizing behavior. The psychological construct of empathy has also shown to be predictive of such behavior, but little is known about the potential interaction between these two different risk factors in predicting externalizing behavior. We examined the moderating role of empathy on the association between resting heart rate in childhood and adolescence with externalizing behavior by young adulthood using two subsets of participants from the Longitudinal Risk Factors for Antisocial Behavior project: Subsample 1 (n = 697) at ages 9–10 and 19–20 years and Subsample 2 (n = 394) at ages 14–15 and 19–20 years. Linear and logistic regressions showed that empathy moderated the association between resting heart rate in adolescence and externalizing behavior by young adulthood. Among individuals with low but not high levels of empathy, increased resting heart rate predicted lower levels of externalizing behavior. Interventions enhancing empathic skills in individuals with psychophysiological risk profiles could be beneficial.

Background: We examined associations of adverse perinatal events with offspring violent and non-violent criminal convictions in men and women.

Methods: All singleton births between 1973 and 1995 (n =1,146,570 men, n =1,085,217 women) were identified through Swedish population-based registers. Information about adverse perinatal events was retrieved from the Medical Birth Register. Outcomes were criminal convictions collected from the National Crime Register. We estimated absolute and relative risks of being convicted of criminal convictions using the Kaplan-Meier method and survival analyses for men and women separately. We also tested for differences in magnitudes of associations for men versus women.

Results: Several adverse perinatal events were associated with an increased risk of violent and non-violent criminal convictions in both men and women. Associations between low birth weight, smallness relative to gestational age and preterm birth with non-violent criminal convictions were statistically significantly higher for men than for women. There was a dose-dependent association between adverse perinatal events with violent and non-violent criminal convictions for both men and women, indicated by the strengthened magnitude of HR estimates with exposure to an increasing number of adverse perinatal events.

Conclusions: Adverse perinatal events are associated with violent and non-violent criminal convictions in men and women, with some differences in risk estimates between sexes. Findings are compatible with theoretical accounts implicating disruption of the neurodevelopment during the perinatal period.

Background: We examined associations of adverse perinatal events with offspring violent and non-violent criminal convictions in men and women.

Methods: All singleton births between 1973 and 1995 (n = 1,146,570 men, n = 1,085,217 women) were identified through Swedish population-based registers. Information about adverse perinatal events was retrieved from the Medical Birth Register. Outcomes were criminal convictions collected from the National Crime Register. We estimated absolute and relative risks of being convicted of criminal convictions using the Kaplan-Meier method and survival analyses for men and women separately. We also tested for differences in magnitudes of associations for men versus women.

Results: Several adverse perinatal events were associated with an increased risk of violent and non–violent criminal convictions in both men and women. Associations between low birth weight, small nessrelative to gestational age and preterm birth with non–violent criminal convictions were statistically significantly higher for men than for women. There was a dose–dependent association between adverse perinatal events with violent and non–violent criminal convictions for both men and women, indicated by the strengthened magnitude of HR estimates with exposure to an increasing number of adverse perinatal events.

Conclusions: Adverse perinatal events are associated with violent and non-violent criminal convictions in men and women, with some differences in risk estimates between sexes. Findings are compatible with theoretical accounts implicating disruption of the neurodevelopment during the perinatal period.

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.

Low resting heart rate (HR) is a well-replicated correlate of antisocial behavior. Previous findings have suggested that low resting HR is associated with criminal offending, psychopathy, conduct problems and aggression. More recent work has also indicated that low systolic blood pressure is associated with an increased risk of criminal offending. However, little is known about the predictive value of low autonomic arousal for reoffending. Thus, the present study examined associations of resting HR and systolic blood pressure with reoffending. We used Swedish population-based registers to conduct a cohort study of all male conscripts born between 1958 and 1990 who had been convicted of a crime (N=407,533). Resting HR and systolic blood pressure was measured at the conscription assessment. Criminal convictions were obtained from the National Crime Register. We used survival analyses to test for associations between resting HR and systolic blood pressure with reoffending while covarying for socioeconomic status, height, weight, physical energy capacity and birth year. A lower resting HR was associated with an increased risk of reoffending for violent and nonviolent crime compared to a higher resting HR. Lower systolic blood pressure was also associated with an increased risk of reoffending for violent and nonviolent crime compared to a higher systolic blood pressure. Low autonomic arousal should be further investigated as a predictor for reoffending as it may help to improve identification of individuals at risk for repeated criminal justice involvement.

Background: Youth offenders have a high risk of being injured or dying prematurely. However, few studies have considered the role of imprisonment and potential childhood risk factors for these high rates.

Aim: To examine the risk of unintentional injury and premature death in non-imprisoned and imprisoned youth offenders, and to examine the role of parental criminal convictions and psychiatric disorders and own childhood psychiatric disorders.

Methods: All individuals (N = 1,839,711) born in Sweden between 1978 and 1996 were identified using Swedish population-based registers. The exposure was criminal conviction between ages 15-20 years of age.

Results: Imprisoned youth offenders had the highest risk for unintentional injury (HR = 2.29 [2.19-2.40]) and premature death (HR = 10.76 [9.52-12.16]), followed by nonimprisoned youth offenders, compared to non -convicted youth. All childhood risk factors increased the risk for these outcomes among non-imprisoned youth offenders. Among imprisoned youth offenders, parental criminal convictions and parental psychiatric disorders increased the risk for unintentional injury, and parental psychiatric disorders and own childhood psychiatric disorders increased the risk for premature death.

Conclusions: Our study shows there are robust modifiable childhood risk factors for injury and mortality among youth offenders. However, the importance of them to assess risk may differ between non-imprisoned and imprisoned youth offenders.

Background: Psychiatric diagnoses are important risk factors for criminal convictions, but few longitudinal studies have examined comorbidity patterns in relation to youth criminal convictions.

Aim: To explore associations between specific psychiatric diagnoses (substance use disorder (SUD), ADHD, depression, PTSD, intellectual disabilities (ID), and autism spectrum disorders (ASD)) and comorbidities of internalizing, externalizing, or neurodevelopmental diagnoses (NDD) in relation to risk of non-violent or violent criminal convictions in youth, including potential sex differences.

Methods: Data on 1,411,538 individuals born in Sweden (1985–1998) were obtained from national population-based registers. Exposure was psychiatric diagnoses and outcome was criminal convictions between ages 15 and 20.

Results: 17% of individuals had a psychiatric diagnosis, of whom 20% were convicted of a crime. All diagnoses, except ID and ASD, increased the risk of non-violent and violent crimes. Comorbidities of externalizing and internalizing diagnoses heightened the risk compared to single diagnoses. NDD increased the risk among SUD, depression, and PTSD, while NDD comorbid with another NDD decreased the risk for criminal convictions.

Conclusion: Of the three comorbidity categories, externalizing disorders heightened risk the most, followed by internalizing disorders. This study highlights specific risk patterns for criminal convictions related to comorbidities, and to crime type and sex.

Background: Individuals with Attention-Deficit/Hyperactivity Disorder (ADHD) face an elevated risk of criminal convictions compared to those without ADHD. However, understanding this link involves considering sex differences, coexisting psychiatric conditions, and unmeasured familial factors. This study aimed to explore the connection between ADHD and criminal convictions (both violent and non-violent) in males and females, while also assessing the impact of comorbid psychiatric disorders and familial factors.

Methods: Using Swedish national registers, we identified individuals born between 1986 and 1997 (635,391 males and 600,548 females). ADHD was defined through clinical diagnosis and prescribed medications, while criminal convictions were determined based on Swedish lower court records. Unmeasured familial factors were accounted for using a sibling design approach.

Results: Findings revealed that individuals with ADHD had a notably higher absolute and relative risk of both violent and non-violent criminal convictions compared to those without ADHD. While criminal convictions were more frequent among males with ADHD, females with ADHD exhibited higher relative risks (HR violent 10.50, non-violent 4.04) than their male counterparts (HR violent 6.03, non-violent 3.57). Additionally, lower socioeconomic status (SES) in individuals with ADHD was associated with increased relative risks for criminal convictions compared to individuals with ADHD who had higher SES. Adjusting for childhood and internalizing psychiatric disorders partially attenuated these associations, while substance use disorders (SUD) substantially attenuated them. SUD also contributed to an elevated absolute risk of criminal convictions in both male and female individuals with ADHD. Accounting for unmeasured shared familial factors slightly reduced the estimates, but the association between ADHD and criminal convictions persisted.

Conclusion: In conclusion, ADHD remains a potent independent risk factor for criminal convictions, with varying effects based on gender. This underscores the importance of tailored crime prevention strategies and early interventions for individuals with ADHD, especially when comorbid SUD is present.