Shared familial risk factors between attention-deficit/hyperactivity disorder and overweight/obesity - a population-based familial coaggregation study in Sweden

Excessive body weight in developmental coordination disorder: A systematic review and meta-analysis

Evidence on the link between developmental coordination disorder (DCD) and obesity and overweight is mixed. Based on a pre-registered protocol (PROSPERO: CRD42023429432), we conducted the first systematic review/meta-analysis on the association between DCD and excessive weight. Web of Science, PubMed and an institutional database aggregator were searched until the 18th of December 2023. We assessed study quality using the Newcastle-Ottawa Scale and study heterogeneity using Q and I2 statistics. Data from 22 studies were combined, comprising 11,330 individuals out of which 1861 had DCD. The main analysis showed a significant association between DCD and higher body weight (OR:1.87, 95 % CI =1.43, 2.44). Meta-regression analyses indicated that the relationship was mediated by age, with stronger effects in studies with higher mean age (p 0.004). We conclude that DCD is associated with obesity and overweight, and this association increases with age. Our study could help to implement targeted prevention and intervention measures.

Understanding the impact of non-shared unmeasured confounding on the sibling comparison analysis

BACKGROUND

The sibling comparison analysis is used to deal with unmeasured confounding. It has previously been shown that in the presence of non-shared unmeasured confounding, the sibling comparison analysis may introduce substantial bias depending on the sharedness of the unmeasured confounder and the sharedness of the exposure. We aimed to improve the awareness of this challenge of the sibling comparison analysis.

METHODS

First, we simulated sibling pairs with an exposure, a confounder and an outcome. We simulated sibling pairs with no effect of the exposure on the outcome and with positive confounding. For varying degrees of sharedness of the confounder and the exposure and for varying prevalence of the exposure, we calculated the sibling comparison odds ratio (OR). Second, we provided measures for sharedness of selected treatments based on Danish health data.

RESULTS

The confounded sibling comparison OR was visualized for varying degrees of sharedness of the confounder and the exposure and for varying prevalence of the exposure. The confounded sibling comparison OR was seen to increase with increasing sharedness of the exposure and the confounded sibling comparison OR decreased with an increasing prevalence of exposure. Measures for sharedness of treatments based on Danish health data showed that treatments of chronic diseases have the highest sharedness and treatments of non-chronic diseases have the lowest sharedness.

CONCLUSIONS

Researchers should be aware of the challenge regarding non-shared unmeasured confounding in the sibling comparison analysis, before applying the analysis in non-randomized studies. Otherwise, the sibling comparison analysis may lead to substantial bias.

Growth Trajectories in Stimulant Treated Children and Adolescents: A Qualitative Review of the Literature from Comprehensive Datasets and Registries

Objective: Attention-deficit/hyperactivity disorder (ADHD) treatment with stimulant products has been shown to be safe and effective; however, there are remaining concerns about their possible adverse effects on growth trajectories. We conducted a systematic review of the extant literature derived from ecologically valid databases and registries to assess the body of knowledge about the effects of stimulants on growth trajectories in naturalistic samples. Methods: Using PubMed and PsycINFO, we searched for articles published before February 8, 2023 that focused on growth findings associated with stimulant treatment in pediatric ADHD from comprehensive datasets derived from naturalistic population studies. Results: Of the 1070 articles initially identified, 12 met all inclusion criteria. Sample sizes ranged from 157 to 163,820 youths. Seven of 10 articles examining height found significant decreases in height associated with chronic stimulant treatment that normalized over time in 2 studies. Three articles found no significant association between stimulant treatment and height. No clear associations were identified between cumulative duration and dose of stimulant treatment and adult height. All articles examining weight and six of eight articles examining body mass index (BMI) found significant initial decreases that tended to normalize then increase over time. Longer duration of stimulant medication use was predominantly associated with significant weight and BMI reductions. The effects of stimulant dose on weight and BMI were mostly weak and clinically insignificant. Most studies found no significant association between age at start of stimulant treatment and change in height, weight, or BMI. Most studies did not find significant sex effects in relation to growth parameters. Conclusions: This review of ecologically informative samples revealed that the effects of stimulant treatment on growth trajectories are mainly small and transient. These effects seem to be clinically insignificant for most youth with ADHD who receive stimulant treatment from childhood onto adolescence and adulthood.

Association of ADHD symptoms with type 2 diabetes and cardiovascular comorbidities in adults receiving outpatient diabetes care

Background

The relationship between attention-deficit/hyperactivity disorder (ADHD) symptoms and type 2 diabetes mellitus (T2D) and its cardiovascular outcomes have not been sufficiently studied.

Methods

2,986 adults with T2D from the Joslin Diabetes Center at Upstate Medical University were assessed for ADHD-like symptoms, executive dysfunction, and emotional control using the Adult Self-Report Scale V1.1 (ASRS) expanded version. Surveys were sent electronically, and clinical data were obtained from the electronic medical record. Pearson chi-square test was used for categorical variables association. When ASRS scores were the dependent variable, negative binomial regression correcting for demographic variables that were associated with the ASRS scores was used.

Results

155 (49.2%) of respondents met DSM-5 criteria for ADHD using the ASRS scores; Only ten (3.6%) of respondents had an ICD10 diagnosis of ADHD in their medical record; Forty-three (13.7%) had either a diagnosis of ADHD in the medical history or were taking medications used by people with ADHD. Higher levels of ADHD-like symptoms were found in patients with T2D compared with population norms. There was a modest association of the ASRS executive dysfunction subscale with overall cardiovascular comorbidities (p = 0.03). However, the p-value did not survive the multiple testing correction. Both ADHD-like symptoms and symptoms associated with emotional control, however, were not associated with specific cardiovascular diseases, hypertension, or with HbA1c, LDL-cholesterol, triglycerides, ALT, creatinine, or eGFR.

Conclusion

Our results suggest that adults with T2D attending a tertiary care diabetes clinic are at risk for having ADHD-like symptoms, highlighting the importance of screening for ADHD symptoms in this specialty setting and referring undiagnosed adult patients for further assessment and treatment of ADHD. Larger studies are needed to clarify the relationship between ADHD-like symptoms, executive dysfunction, and emotional control with diabetic control and comorbidities.

Shared Genetic Factors Contributing to the Overlap between Attention-Deficit/Hyperactivity Disorder Symptoms and Overweight/Obesity in Swedish Adolescent Girls and Boys

Attention-deficit/hyperactivity disorder (ADHD) and obesity are positively associated, with increasing evidence that they share genetic risk factors. Our aim was to examine whether these findings apply to both types of ADHD symptoms for female and male adolescents. We used data from 791 girl and 735 boy twins ages 16-17 years to examine sex-specific phenotypic correlations between the presence of ADHD symptoms and overweight/obese status. For correlations exceeding .20, we then fit bivariate twin models to estimate the genetic and environmental correlations between the presence of ADHD symptoms and overweight/obese status. ADHD symptoms and height/weight were parent- and self-reported, respectively. Phenotypic correlations were .30 (girls) and .08 (boys) for inattention and overweight/obese status and .23 (girls) and .14 (boys) for hyperactivity/impulsivity and overweight/obese status. In girls, both types of ADHD symptoms and overweight/obese status were highly heritable, with unique environmental effects comprising the remaining variance. Furthermore, shared genetic effects explained most of the phenotypic correlations in girls. Results suggest that the positive association of both types of ADHD symptoms with obesity may be stronger in girls than boys. Further, in girls, these associations may stem primarily from shared genetic factors.

Shared familial risk factors between autism spectrum disorder and obesity - a register-based familial coaggregation cohort study

BACKGROUND

Meta-analyses suggest an association between autism spectrum disorder (ASD) and obesity, but the factors underlying this association remain unclear. This study investigated the association between ASD and obesity stratified on intellectual disability (ID). In addition, in order to gain insight into possible shared etiological factors, the potential role of shared familial liability was examined.

METHOD

We studied a cohort of 3,141,696 individuals by linking several Swedish nationwide registers. We identified 35,461 individuals with ASD and 61,784 individuals with obesity. Logistic regression models were used to estimate the association between ASD and obesity separately by ID and sex and by adjusting for parental education, psychiatric comorbidity, and psychotropic medication. Potential shared familial etiologic factors were examined by comparing the risk of obesity in full siblings, maternal and paternal half-siblings, and full- and half-cousins of individuals with ASD to the risk of obesity in relatives of individuals without ASD.

RESULTS

Individuals with ASD + ID (OR = 3.76 [95% CI, 3.38-4.19]) and ASD-ID (OR = 3.40 [95% CI, 3.23-3.58]) had an increased risk for obesity compared with individuals without ASD. The associations remained statistically significant when adjusting for parental education, psychiatric comorbidity, and medication. Sex-stratified analyses indicated a higher relative risk for males compared with females, with statistically significant interaction effects for ASD-ID, but not for ASD+ID in the fully adjusted model. First-degree relatives of individuals with ASD+ID and ASD-ID had an increased risk of obesity compared with first-degree relatives of individuals without ASD. The obesity risk was similar in second-degree relatives of individuals with ASD+ID but was lower for and ASD-ID. Full cousins of individuals with ASD+ID had a higher risk compared with half-cousins of individuals with ASD+ID). A similar difference in the obesity risk between full cousins and half-cousins was observed for ASD-ID.

CONCLUSIONS

Individuals with ASD and their relatives are at increased risk for obesity. The risk might be somewhat higher for males than females. This warrants further studies examining potential common pleiotropic genetic factors and shared family-wide environmental factors for ASD and obesity. Such research might aid in identifying specific risks and underlying mechanisms in common between ASD and obesity.

Non-mental diseases associated with ADHD across the lifespan: Fidgety Philipp and Pippi Longstocking at risk of multimorbidity?

Several non-mental diseases seem to be associated with an increased risk of ADHD and ADHD seems to be associated with increased risk for non-mental diseases. The underlying trajectories leading to such brain-body co-occurrences are often unclear - are there direct causal relationships from one disorder to the other, or does the sharing of genetic and/or environmental risk factors lead to their occurring together more frequently or both? Our goal with this narrative review was to provide a conceptual synthesis of the associations between ADHD and non-mental disease across the lifespan. We discuss potential shared pathologic mechanisms, genetic background and treatments in co-occurring diseases. For those co-occurrences for which published studies with sufficient sample sizes exist, meta-analyses have been published by others and we discuss those in detail. We conclude that non-mental diseases are common in ADHD and vice versa and add to the disease burden of the patient across the lifespan. Insufficient attention to such co-occurring conditions may result in missed diagnoses and suboptimal treatment in the affected individuals.

Psychiatric and Nonpsychiatric Comorbidities Among Children With ADHD: An Exploratory Analysis of Nationwide Claims Data in Germany

Objective: This study examined the full spectrum of comorbid disorders in all statutory-health-insured children aged 5 to 14 years with ADHD in 2017 by using nationwide claims data in Germany. Method: Children with ADHD (n = 258,662) were compared for the presence of 864 comorbid diseases with a control group matched by gender, age, and region of residence (n = 2,327,958). Results: Among others, metabolic disorders (odds ratio [OR] = 9.18; 95% confidence interval [CI] = [8.43, 9.99]), viral pneumonia (OR = 4.95; 95% CI = [2.37, 10.33]), disorders of white blood cells (OR = 4.55; 95% CI = [3.83, 5.40]), kidney failure (OR = 3.33; 95% CI = [2.65, 4.18]), hypertension (OR = 3.26; 95% CI = [3.00, 3.55]), obesity (OR = 2.85; 95% CI = [2.80, 2.91]), type 2 diabetes (OR = 2.61; 95% CI = [2.11, 3.23]), migraine (OR = 2.49; 95% CI = [2.37, 2.61]), asthma (OR = 2.19; 95% CI = [2.16, 2.22]), atopic dermatitis (OR = 2.10; 95% CI = [2.16, 2.23]), juvenile arthritis (OR = 1.56; 95% CI = [1.39, 1.76]), glaucoma (OR = 1.51; 95% CI = [1.30, 1.75]), and type 1 diabetes (OR = 1.30; 95% CI = [1.20, 1.40]) were more likely to be diagnosed in ADHD children. Conclusion: Along with psychiatric diseases, various somatic diseases were more common in ADHD children. The results have direct implications for patient care, including fine-grained diagnostics and personalized therapy.

Maternal pre-pregnancy overweight/obesity and the risk of attention-deficit/hyperactivity disorder in offspring: a systematic review, meta-analysis and quasi-experimental family-based study

BACKGROUND

Previous studies are inconclusive concerning the association between maternal pre-pregnancy overweight/obesity and risk of attention-deficit/hyperactivity disorder (ADHD) in offspring. We therefore conducted a systematic review and meta-analysis to clarify this association. To address the variation in confounding adjustment between studies, especially inadequate adjustment of unmeasured familial confounding in most studies, we further performed cousin and sibling comparisons in a nationwide population-based cohort in Sweden.

METHODS

We searched PubMed, Embase and PsycINFO during 1975-2018. We used random-effects models to calculate pooled risk ratios (RRs) with 95% confidence interval. In the population-based study, Cox proportional hazard models were used to calculate the unadjusted hazard ratios (HRs) and HRs adjusted for all confounders identified in previous studies. Stratified Cox models were applied to data on full cousins and full siblings to further control for unmeasured familial confounding.

RESULTS

Eight cohorts with a total of 784 804 mother-child pairs were included in the meta-analysis. Maternal overweight [RRoverweight = 1.31 (1.25-1.38), I2 = 6.80%] and obesity [RRobesity = 1.92 (1.84-2.00), I2 = 0.00%] were both associated with an increased risk of ADHD in offspring. In the population-based cohort of 971 501 individuals born between 1992 and 2004, unadjusted Cox models revealed similar associations [HRoverweight = 1.30 (1.28-1.34), HRobesity = 1.92 (1.87-1.98)]. These associations gradually attenuated towards the null when adjusted for measured confounders [HRoverweight = 1.21 (1.19-1.25), HRobesity = 1.60 (1.55-1.65)], unmeasured factors shared by cousins [HRoverweight = 1.10 (0.98-1.23), HRobesity = 1.44 (1.22-1.70)] and unmeasured factors shared by siblings [HRoverweight = 1.01 (0.92-1.11), HRobesity = 1.10 (0.94-1.27)].

CONCLUSION

Pre-pregnancy overweight/obesity is associated with an increased risk of ADHD in offspring. The observed association is largely due to unmeasured familial confounding.

Genetic and environmental sources of familial coaggregation of obsessive-compulsive disorder and suicidal behavior: a population-based birth cohort and family study

Obsessive-compulsive disorder (OCD) is associated with high risk of suicide. It is yet unknown whether OCD and suicidal behaviors coaggregate in families and, if so, what are the mechanisms underlying this coaggregation. In a population-based birth cohort and family study, we linked individuals born in Sweden in 1967-2003 (n = 3,594,181) to their parents, siblings, and cousins, and collected register-based diagnoses of OCD, suicide attempts, and deaths by suicide and followed them until December 31, 2013. We also applied quantitative genetic modeling to estimate the contribution of genetic and environmental factors to the familial coaggregation of OCD and suicidal behavior. An elevated risk of suicide attempts was observed across all relatives of individuals with OCD, increasing proportionally to the degree of genetic relatedness, with odds ratios (OR) ranging from 1.56 (95% confidence interval (CI) 1.49-1.63) in parents to 1.11 (95% CI 1.07-1.16) in cousins. The risk of death by suicide also increased alongside narrowing genetic distance, but was only significant in parents (OR 1.55; 95% CI 1.40-1.72) and full siblings (OR 1.80; 95% CI 1.43-2.26) of individuals with OCD. Familial coaggregation of OCD and suicide attempts was explained by additive genetic factors (60.7%) and non-shared environment (40.4%), with negligible contribution of shared environment. Similarly, familial coaggregation with death by suicide was attributed to additive genetics (65.8%) and nonshared environment (34.2%). Collectively, these observations indicate that OCD and suicidal behaviors coaggregate in families largely due to genetic factors. The contribution of unique environment is also considerable, providing opportunities to target high-risk groups for prevention and treatment.

Attention Deficit Hyperactivity Disorder: Association With Obesity and Eating Disorders

Attention deficit hyperactivity disorder (ADHD) is one of the most common treatable psychiatric illnesses that affect all age groups from children to adults. Most commonly it is diagnosed in childhood or during teenage years. It can affect the mental and physical health of an individual and disrupt normal academic, career, and social functioning. The quality of life of the individual is affected; thus if diagnosed and treated, the results are good. Obesity and eating disorders are one of the comorbidities associated with ADHD and can lead to various other health problems. This study was done to find out the association between ADHD, obesity, eating disorders, and the effect of medication. We collected data from various studies through multiple electronic databases such as PubMed and Google Scholar. We found 8610 relevant articles and finally narrowed it down to 30 using various criteria. An association was found between ADHD, obesity, and eating disorders, although the mechanism linking ADHD, obesity, and eating disorders still remains unclear according to most studies. Some studies say ADHD medication helps in losing gained weight; some say they do not affect the weight.

Proinflammatory mediators and their associations with medication and comorbid traits in children and adults with ADHD

Peripheral immune activation can influence neurodevelopment and is increased in autism, but is less explored in attention deficit hyperactivity disorder (ADHD). Patients with ADHD often display comorbid autism traits and gastrointestinal (GI) symptoms. Plasma protein levels of two acute phase reactants, C-reactive protein (CRP) and serum amyloid A (SAA), and two endothelial adhesion molecules, soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1), which share important roles in inflammation, were analyzed in 154 patients with ADHD and 61 healthy controls. Their associations with ADHD diagnosis, severity, medication and comorbid autistic symptoms, emotion dysregulation and GI symptoms were explored. The ADHD patients had increased levels of sICAM-1 and sVCAM-1 compared to healthy controls (p = 8.6e-05, p = 6.9e-07, respectively). In children with ADHD, the sICAM-1 and sVCAM-1 levels were higher among those with ADHD medication than among children (p = 0.0037, p = 0.0053, respectively) and adults (p = 3.5e-09, p = 1.9e-09, respectively) without ADHD medication. Among the adult ADHD patients, higher sICAM-1 levels were associated with increased comorbid autistic symptoms in the domains attention to detail and imagination (p = 0.0081, p = 0.00028, respectively), and higher CRP levels were associated with more GI symptoms (p = 0.014). sICAM-1 and sVCAM-1 levels were highly correlated with each other, and so were CRP and SAA levels. To conclude, vascular inflammatory activity may be overrepresented in ADHD, with elevated sICAM-1 and sVCAM-1 levels and this may in children be a consequence of current ADHD medication, and in adults relate to increased comorbid autistic symptoms. Replication is warranted.

Global prevalence of obesity, overweight and underweight in children, adolescents and adults with autism spectrum disorder, attention-deficit hyperactivity disorder: A systematic review and meta-analysis

Individuals with autism spectrum disorder (ASD) or attention-deficit hyperactivity disorder (ADHD) may have unhealthy bodyweight. This meta-analysis was performed to understand the weight status in individuals with ASD or ADHD. PubMed, Embase, Cochrane and ISI Web of Science databases were searched from inception until June 2020 to identify relevant studies. Prevalence estimates and their 95% confidence intervals (CIs) of obesity, overweight and underweight were separately pooled using random-effects models. A total of 95 studies were included in the meta-analysis. The pooled estimates of the prevalence of obesity, overweight and underweight were 21.8%, 19.8% and 6.4% in individuals with ASD and 14.7%, 20.9% and 4.0% in individuals with ADHD. In subgroup analyses, an increasing trend in the prevalence of unhealthy weight was observed from children aged 2 to 5 years to adults with ASD (obesity: from 16.7% to 31.3%, overweight: from 16.2% to 27.2%, underweight from 5.3% to 8.6%) and from children aged 6 to 12 years to adults with ADHD (obesity: from 13.5% to 19.3%, overweight: from 18.8% to 31.2%). The worrisome epidemic of obesity and overweight in individuals with ASD, ADHD highlighted the need for weight management.

Negative Affectivity and Emotion Dysregulation as Mediators between ADHD and Disordered Eating: A Systematic Review

Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with disordered eating, especially addictive-like eating behavior (i.e., binge eating, food addiction, loss of control overeating). The exact mechanisms underlying this association are unclear. ADHD and addictive-like eating behavior are both associated with negative affectivity and emotion dysregulation, which we hypothesized are mediators of this relationship. The purpose of this systematic review was to review the evidence related to this hypothesis from studies assessing the relationship between childhood or adulthood ADHD symptomatology, negative affectivity, emotion dysregulation and addictive-like eating behavior. The systematic review followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) recommendations. The literature search was conducted in PubMed and PsycINFO (publication date: January 2015 to August 2020; date of search: 2 September 2020). Out of 403 potentially relevant articles, 41 were retained; 38 publications reported that ADHD and disordered eating or addictive-like eating behavior were significantly associated, including 8 articles that suggested a mediator role of negative affectivity or emotion dysregulation. Sixteen publications reported that the association between ADHD symptomatology and disordered eating or addictive-like eating behavior differed according to gender, eating behavior and ADHD symptoms (hyperactivity, impulsivity and inattention). We discuss the practical implications of these findings and directions future research.

Parental Weight Status and Offspring Behavioral Problems and Psychiatric Symptoms

OBJECTIVES

To assess relations of prepregnancy maternal and paternal obesity with offspring behavioral problems and psychiatric symptoms at 7-8 years in the Upstate KIDS study, a prospective cohort study.

STUDY DESIGN

Maternal body mass index (BMI) was calculated from prepregnancy height and weight provided in vital records or self-report at 4 months postpartum. Mothers reported paternal height and weight. At 7-8 years, mothers indicated if their children had been diagnosed with ADHD or anxiety (n = 1915). Additionally, children's behavior was measured with the Strengths and Difficulties Questionnaire at 7 years of age (n = 1386) and the Vanderbilt ADHD Diagnostic Parent Rating Scale at 8 years of age (n = 1484). Based on Strengths and Difficulties Questionnaire scores, we identified children with borderline behavioral problems. Adjusted risk ratios (aRR) and 95% CIs were estimated with robust multivariable Poisson regression.

RESULTS

Compared with children of mothers with a BMI of <25, children whose mothers had BMI 25-30, 30-35, and ≥35 kg/m2 had higher risks of reported ADHD (aRR, 1.14, 95% CI, 0.78-1.69; aRR, 1.96, 95% CI, 1.29-2.98; and aRR, 1.82, 95% CI,1.21-2.74, respectively). Risks of hyperactivity problems identified by the Strengths and Difficulties Questionnaire and a positive screen for inattentive or hyperactive/impulsive behavior with the Vanderbilt ADHD Diagnostic Parent Rating Scale were also higher with increasing maternal prepregnancy BMI. Paternal BMI was not associated with child outcomes.

CONCLUSIONS

Our findings suggest that maternal, rather than paternal, obesity is associated with maternal report of child ADHD diagnosis and inattentive or hyperactivity problems. Further research is needed to understand how maternal obesity might influence these behavioral changes during or after pregnancy.

Genetic correlations of psychiatric traits with body composition and glycemic traits are sex- and age-dependent

Body composition is often altered in psychiatric disorders. Using genome-wide common genetic variation data, we calculate sex-specific genetic correlations amongst body fat %, fat mass, fat-free mass, physical activity, glycemic traits and 17 psychiatric traits (up to N = 217,568). Two patterns emerge: (1) anorexia nervosa, schizophrenia, obsessive-compulsive disorder, and education years are negatively genetically correlated with body fat % and fat-free mass, whereas (2) attention-deficit/hyperactivity disorder (ADHD), alcohol dependence, insomnia, and heavy smoking are positively correlated. Anorexia nervosa shows a stronger genetic correlation with body fat % in females, whereas education years is more strongly correlated with fat mass in males. Education years and ADHD show genetic overlap with childhood obesity. Mendelian randomization identifies schizophrenia, anorexia nervosa, and higher education as causal for decreased fat mass, with higher body fat % possibly being a causal risk factor for ADHD and heavy smoking. These results suggest new possibilities for targeted preventive strategies.

Associations Between Attention-Deficit/Hyperactivity Disorder and Various Eating Disorders: A Swedish Nationwide Population Study Using Multiple Genetically Informative Approaches

BACKGROUND

Although attention-deficit/hyperactivity disorder (ADHD) and eating disorders (EDs) frequently co-occur, little is known about the shared etiology. In this study, we comprehensively investigated the genetic association between ADHD and various EDs, including anorexia nervosa (AN) and other EDs such as bulimia nervosa.

METHODS

We applied different genetically informative designs to register-based information of a Swedish nationwide population (N = 3,550,118). We first examined the familial coaggregation of clinically diagnosed ADHD and EDs across multiple types of relatives. We then applied quantitative genetic modeling in full-sisters and maternal half-sisters to estimate the genetic correlations between ADHD and EDs. We further tested the associations between ADHD polygenic risk scores and ED symptoms, and between AN polygenic risk scores and ADHD symptoms, in a genotyped population-based sample (N = 13,472).

RESULTS

Increased risk of all types of EDs was found in individuals with ADHD (any ED: odds ratio [OR] = 3.97, 95% confidence interval [CI] = 3.81, 4.14; AN: OR = 2.68, 95% CI = 2.15, 2.86; other EDs: OR = 4.66, 95% CI = 4.47, 4.87; bulimia nervosa: OR = 5.01, 95% CI = 4.63, 5.41) and their relatives compared with individuals without ADHD and their relatives. The magnitude of the associations decreased as the degree of relatedness decreased, suggesting shared familial liability between ADHD and EDs. Quantitative genetic models revealed stronger genetic correlation of ADHD with other EDs (.37, 95% CI = .31, .42) than with AN (.14, 95% CI = .05, .22). ADHD polygenic risk scores correlated positively with ED symptom measures overall and with the subscales Drive for Thinness and Body Dissatisfaction despite small effect sizes.

CONCLUSIONS

We observed stronger genetic association with ADHD for non-AN EDs than for AN, highlighting specific genetic correlation beyond a general genetic factor across psychiatric disorders.

The Association between ADHD and Obesity: Intriguing, Progressively More Investigated, but Still Puzzling

This narrative review is aimed at presenting the most recent evidence on the association between attention-deficit/hyperactivity disorder (ADHD) and obesity. The review is informed by previous relevant systematic reviews and a search in Pubmed and PsycINFO up to 1 August 2019. Although the association between ADHD and obesity would seem, at first, paradoxical, in the past two decades there has been an increasing number of studies on this topic. The present review shows that there is meta-analytic evidence supporting a significant association between these two conditions, at least in adults. Growing evidence is also being published on the genetic and environmental factors underlying the association. However, the cause–effects paths, as well as the exact mechanisms explaining the association, remain unclear. Additionally, empirical evidence guiding the management/treatment of patients with the two conditions is still limited. Therefore, after almost 20 years from the first report of a link between ADHD and obesity, this association continues to be puzzling.

[Impulsivity and obesity in children with Attention Deficit Hyperactivity Disorder: A clinical, neuropsychological and magnetic resonance spectroscopy exploratory study]

OBJECTIVES

Relationship between Attention Deficit Hyperactivity Disorder (ADHD) and obesity in adults and children had previously been established in research studies. Brain imaging studies pointed out the important role of the prefrontal region in both ADHD and obesity. However, the underlying link between ADHD and obesity is not well understood. The hypothesis that impulsivity could play a role has been explored in clinical studies of ADHD and Binge Eating Disorders or Loss of Control Eating, with contradictory results. Our study aims to compare children with ADHD and obesity to children with ADHD and normal weight. We propose to compare these two populations with clinical, neuropsychological and brain spectroscopy investigation, focusing specifically on impulsivity items.

METHOD

Ten children presenting overweight or obesity were selected from a larger population of children with ADHD (5-12y) and paired with regard to gender and age with ten children with ADHD and normal weight from the same population. Conners Rating scales version parents (CPRS) and teachers (CTRS), Conners' Continuous Performance Test II (CPT-II), and Magnetic Resonance Spectroscopy (MRS) metabolites in five regions of interest (left and right prefrontal, left and right striatal and left cerebellum regions) were measured for all the children. For MRS, ratio to creatinine levels of following metabolites were measured: glycerophosphocholine+phosphocholine/creatinine (GPC+PCh/Cr), glutamate+glutamine (Glu+Gln/Cr), myoinositol (mI/Cr) et N-acétylaspartate+N-acétylaspartylglutamate (NAA+NAAG/Cr).

RESULTS

Hyperactivity/Impusivity and Conners Global Index (CGI) subscales of Conners rating scales showed a higher rate of impulsivity in children with ADHD and obesity as compared to children with ADHD and normal weight. Neuropsychological results were comparable in the two groups. Finally, MRS showed a higher GPC+PCh/Cr ratio in right prefrontal cortex in children with ADHD and obesity as compared to children with ADHD and normal weight.

CONCLUSIONS

Our results are concordant with the hypothesis that impulsivity could be the link between obesity and ADHD in a population of children with ADHD. The right prefrontal regions seem to be areas of interests that need more research in the study of the link between obesity and ADHD.

Attention-deficit/hyperactivity disorder and clinically diagnosed obesity in adolescence and young adulthood: a register-based study in Sweden

BACKGROUND

A recent family study of young adult males suggests a shared familial liability between attention-deficit/hyperactivity disorder (ADHD) and high body mass index (BMI), and a genome-wide meta-analysis reported a genetic correlation of 0.26 between ADHD and BMI. To date, it is unclear whether these findings generalize to the relationship between ADHD and clinically diagnosed obesity.

METHOD

By linking the Swedish national registers, we identified 25 38 127 individuals born between 1973 and 2000, together with their siblings and cousins. The risk of clinical obesity in individuals with ADHD was compared with the risk in those without ADHD. The relative contributions of genetic and environmental factors to the association between ADHD and clinical obesity were examined via assessment of the familial co-aggregation of the two conditions and quantitative genetic analysis.

RESULTS

Individuals with ADHD were at an increased risk of clinical obesity compared with those without (risk difference 3.73%, 95% confidence interval (CI) 3.55-3.90%; risk ratio 3.05, 95% CI 2.95-3.15). Familial co-aggregation of ADHD and clinical obesity was detected and the strength of the co-aggregation decreased by decreasing genetic relatedness. The correlation between the liabilities to ADHD and clinical obesity can be entirely attributed to their genetic correlation (rg 0.30, 95% CI 0.17-0.44).

CONCLUSION

The association between ADHD and clinical obesity in adolescence and young adulthood can be entirely attributed to genetic underpinnings shared by the two conditions. Children with ADHD should be monitored for weight gain so that preventive measures can be taken for those on a suboptimal trajectory.

Genetics of attention deficit hyperactivity disorder

Decades of research show that genes play an vital role in the etiology of attention deficit hyperactivity disorder (ADHD) and its comorbidity with other disorders. Family, twin, and adoption studies show that ADHD runs in families. ADHD's high heritability of 74% motivated the search for ADHD susceptibility genes. Genetic linkage studies show that the effects of DNA risk variants on ADHD must, individually, be very small. Genome-wide association studies (GWAS) have implicated several genetic loci at the genome-wide level of statistical significance. These studies also show that about a third of ADHD's heritability is due to a polygenic component comprising many common variants each having small effects. From studies of copy number variants we have also learned that the rare insertions or deletions account for part of ADHD's heritability. These findings have implicated new biological pathways that may eventually have implications for treatment development.

Overweight in family members of probands with ADHD

The widely reported association between ADHD and overweight may be attributable to genetic and environmental factors also present in unaffected family members. Therefore, the purpose of this study was to examine the association between ADHD and overweight within families. A cohort was used of families with at least one member with ADHD, recruited as part of the Dutch node of the International Multicenter ADHD Genetics (IMAGE) study, with assessments taking place between 2003 and 2006, 2009 and 2012, and 2013 and 2015. The three assessment waves yielded N = 1828 youth assessments and N = 998 parent assessments from N = 447 unique families. Overweight was defined as a body mass index (BMI) ≥ 85th percentile for youth of the same age and sex; overweight in adults as a BMI ≥ 25. Effects of age, gender, and medication use (psychostimulants, antipsychotics, and melatonin) were taken into account. Generalized estimation equations were used to correct for within-family and within-subject correlations. There was no difference in risk between ADHD-affected youth and their unaffected siblings (OR 0.92, 95% CI 0.78-1.09). However, compared to population prevalence data, all ADHD family members alike were at increased risk for being overweight: ADHD-affected youth (OR 1.33, 95% CI 1.13-1.59), unaffected siblings (OR 1.73, 95% CI 1.45-2.08), mothers (OR 1.74, 95% CI 1.40-2.17) and fathers (OR 1.78, 95% CI 1.46-2.15). Parental overweight-but not parental ADHD-was predictive of offspring overweight (mothers OR 1.40; 95% CI 1.14-1.73, fathers OR 1.83; 95% CI 1.41-2.36). Being overweight runs in ADHD families, yet is not specifically linked to ADHD within families. Shared unhealthy lifestyle factors (including nutrition, sleep, exercise, stress) as well as genetic factors shared by family members likely explain the findings.

Common psychiatric and metabolic comorbidity of adult attention-deficit/hyperactivity disorder: A population-based cross-sectional study

Attention-deficit/hyperactivity disorder (ADHD) is often comorbid with other psychiatric conditions in adults. Yet, less is known about its relationship with common metabolic disorders and how sex and ageing affect the overall comorbidity patterns of adult ADHD. We aimed to examine associations of adult ADHD with several common psychiatric and metabolic conditions. Through the linkage of multiple Swedish national registers, 5,551,807 adults aged 18 to 64 years and living in Sweden on December 31, 2013 were identified and assessed for clinical diagnoses of adult ADHD, substance use disorder (SUD), depression, bipolar disorder, anxiety, type 2 diabetes mellitus (T2DM), and hypertension. Logistic regression models and regression standardization method were employed to obtain estimates of prevalence, prevalence difference (PD), and prevalence ratio (PR). All comorbid conditions of interest were more prevalent in adults with ADHD (3.90% to 44.65%) than in those without (0.72% to 4.89%), with the estimated PRs being over nine for psychiatric conditions (p < 0.001) and around two for metabolic conditions (p < 0.001). Sex differences in the prevalence of comorbidities were observed among adults with ADHD. Effect modification by sex was detected on the additive scale and/or multiplicative scale for the associations of adult ADHD with all comorbidities. ADHD remained associated with all comorbidities in older adults aged 50 to 64 when all conditions were assessed from age 50 onwards. The comorbidity patterns of adult ADHD underscore the severity and clinical complexity of the disorder. Clinicians should remain vigilant for a wide range of psychiatric and metabolic problems in ADHD affected adults of all ages and both sexes.

Association of Polygenic Risk for Attention-Deficit/Hyperactivity Disorder With Co-occurring Traits and Disorders

BACKGROUND

A recent large-scale mega genome-wide association study identified, for the first time, genetic variants at 12 loci significantly associated with attention-deficit/hyperactivity disorder (ADHD). In this study we use a powerful polygenic approach, with polygenic scores derived from the genome-wide association study, to investigate the etiological overlap between ADHD and frequently co-occurring traits and disorders.

METHODS

Polygenic risk scores for ADHD derived from the mega genome-wide association study (20,183 cases and 35,191 control subjects) were computed in a large-scale adult population sample (N = 135,726) recruited by the UK Biobank. Regression analyses were conducted to investigate whether polygenic risk for ADHD is associated with related traits and disorders in this population sample. The effects of sex were investigated via inclusion of an interaction term in the models.

RESULTS

Polygenic risk for ADHD significantly and positively predicted body mass index (R2 = .45%; p = 5 × 10-129), neuroticism (R2 = .09%; p = 2 × 10-24), depression (R2 = .11%; p = 2 × 10-13), anxiety (R2 = .06%; p = 3 × 10-4), risk taking (R2 = .12%; p = 9 × 10-25), alcohol intake (R2 = .09%; p = 8 × 10-29), smoking (R2 = .33%; p = 4 × 10-21), alcohol dependency (R2 = .21%; p = 5 × 10-6), and negatively predicted verbal-numerical reasoning (R2 = .38%; p = 5 × 10-36). Polygenic risk scores did not significantly predict schizophrenia or bipolar disorder, although this may be because of the small number of diagnostic cases. We found no interaction effects between polygenic risk for ADHD and sex on any phenotypes.

CONCLUSIONS

Our findings suggest that common genetic variation underlying risk for clinically diagnosed ADHD also contributes to higher body mass index, neuroticism, anxiety and depressive disorders, alcohol and nicotine use, risk taking, and lower general cognitive ability in the general population. These findings suggest that the co-occurrence of several traits with ADHD is partly explained by the same common genetic variants.

Attention deficit/hyperactivity-disorder and obesity: A review and model of current hypotheses explaining their comorbidity

Available meta-analyses point to a significant association between attention-deficit/hyperactivity disorder (ADHD) and obesity. The possible mechanisms underlying this relationship are unclear. Here, we overview the studies aimed at identifying the factors contributing to the comorbidity between ADHD and obesity, including genetic factors, fetal programming, executive dysfunctions, psychosocial stress, factors directly related to energy balance, and sleep patterns alterations. The bulk of current research has focused on reduced physical activity and abnormal eating patterns as possible causes of weight gain in individuals with ADHD. Further research is needed to explore the specific role of executive dysfunctions. None of the available published studies have evaluated physiological mechanisms such as hormonal and metabolic disorders or inappropriate neurobiological regulation of appetite. Research exploring the genetic basis for the coexistence of ADHD and obesity and epigenetic mechanisms, with particular emphasis on stress, both pre- and postnatal, seems particularly promising. Here, we propose a biopsychosocial model to integrate current findings and move the field forward to gain insight into the ADHD-obesity relationship.

Familial Liability to Epilepsy and Attention-Deficit/Hyperactivity Disorder: A Nationwide Cohort Study

BACKGROUND

Epilepsy and attention-deficit/hyperactivity disorder (ADHD) are strongly associated; however, the underlying factors contributing to their co-occurrence remain unclear. A shared genetic liability has been proposed as one possible mechanism. Therefore, our goal in this study was to investigate the familial coaggregation of epilepsy and ADHD and to estimate the contribution of genetic and environmental risk factors to their co-occurrence.

METHODS

We identified 1,899,654 individuals born between 1987 and 2006 via national Swedish registers and linked each individual to his or her biological relatives. We used logistic regression to estimate the association between epilepsy and ADHD within individual and across relatives. Quantitative genetic modeling was used to decompose the cross-disorder covariance into genetic and environmental factors.

RESULTS

Individuals with epilepsy had a statistically significant increased risk of ADHD (odds ratio [OR] = 3.47, 95% confidence interval [CI] = 3.33-3.62). This risk increase extended to children whose mothers had epilepsy (OR = 1.85, 95% CI = 1.75-1.96), children whose fathers had epilepsy (OR = 1.64, 95% CI = 1.54-1.74), full siblings (OR = 1.56, 95% CI = 1.46-1.67), maternal half siblings (OR = 1.28, 95% CI = 1.14-1.43), paternal half siblings (OR = 1.10, 95% CI = 0.96-1.25), and cousins (OR = 1.15, 95% CI = 1.10-1.20). The genetic correlation was 0.21 (95% CI = 0.02-0.40) and explained 40% of the phenotypic correlation between epilepsy and ADHD, with the remaining variance largely explained by nonshared environmental factors (49%, nonshared environmental correlation = 0.36, 95% CI = 0.23-0.49). The contribution of shared environmental factors to the cross-disorder overlap was not statistically significant (11%, shared environmental correlation = 0.32, 95% CI = -0.16-0.79).

CONCLUSIONS

This study demonstrates a strong and etiologically complex association between epilepsy and ADHD, with shared familial factors and risk factors unique to the individual contributing to co-occurrence of the disorders. Our findings suggest that epilepsy and ADHD may share less genetic risk as compared with other neurodevelopmental disorders.