Polygenic risk score analysis revealed shared genetic background in attention deficit hyperactivity disorder and narcolepsy

Schizophrenia polygenic risk scores, clinical variables and genetic pathways as predictors of phenotypic traits of bipolar I disorder

AIM

We investigated the predictive value of polygenic risk scores (PRS) derived from the schizophrenia GWAS (Trubetskoy et al., 2022) (SCZ3) for phenotypic traits of bipolar disorder type-I (BP-I) in 1878 BP-I cases and 2751 controls from Romania and UK.

METHODS

We used PRSice-v2.3.3 and PRS-CS for computing SCZ3-PRS for testing the predictive power of SCZ3-PRS alone and in combination with clinical variables for several BP-I subphenotypes and for pathway analysis. Non-linear predictive models were also used.

RESULTS

SCZ3-PRS significantly predicted psychosis, incongruent and congruent psychosis, general age-of-onset (AO) of BP-I, AO-depression, AO-Mania, rapid cycling in univariate regressions. A negative correlation between the number of depressive episodes and psychosis, mainly incongruent and an inverse relationship between increased SCZ3-SNP loading and BP-I-rapid cycling were observed. In random forest models comparing the predictive power of SCZ3-PRS alone and in combination with nine clinical variables, the best predictions were provided by combinations of SCZ3-PRS-CS and clinical variables closely followed by models containing only clinical variables. SCZ3-PRS performed worst. Twenty-two significant pathways underlying psychosis were identified.

LIMITATIONS

The combined RO-UK sample had a certain degree of heterogeneity of the BP-I severity: only the RO sample and partially the UK sample included hospitalized BP-I cases. The hospitalization is an indicator of illness severity. Not all UK subjects had complete subphenotype information.

CONCLUSION

Our study shows that the SCZ3-PRS have a modest clinical value for predicting phenotypic traits of BP-I. For clinical use their best performance is in combination with clinical variables.

Insomnia Polygenic Component on Attention Deficit-Hyperactivity Disorder: Exploring this Association Using Genomic Data from Brazilian Families

Introduction  Insomnia is highly prevalent among individuals with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the biological mechanisms shared between both conditions is still elusive. We aimed to investigate whether insomnia's genomic component is able to predict ADHD in childhood and adolescence. Methods  A Brazilian sample of 259 ADHD probands and their biological parents were included in the study. Their genomic DNA genotypes were used to construct the polygenic risk score for insomnia (Insomnia PRS), using the largest GWAS summary statistics as a discovery sample. The association was tested using logistic regression, under a case-pseudocontrol design. Results  Insomnia PRS was nominally associated with ADHD (OR = 1.228, p  = 0.022), showing that the alleles that increase the risk for insomnia also increase the risk for ADHD. Discussion  Our results suggest that genetic factors associated with insomnia may play a role in the ADHD genetic etiology, with both phenotypes likely to have a shared genetic mechanism.

Associations between sleep problems in children with ADHD and parental insomnia and ADHD symptoms

Sleep problems are common in children with attention deficit hyperactivity disorder (ADHD). Children's sleep problem may influence, and be influenced by, parents' sleep problems as well as parents' ADHD symptoms. In the current study we examined the associations of parent-rated sleep quality and sleep timing of pre-adolescent children with parental insomnia symptoms, parental ADHD symptoms and dysfunctional attitudes and beliefs about sleep in a convenience sample recruited by advertisement (N = 120). Childhood sleep problems were common in the sample, with 82% of children exceeding the threshold for the presence of a paediatric sleep disorder. Children's sleep quality showed minimal association with their sleep timing and chronotype. Parental insomnia symptoms, ADHD symptoms and dysfunctional beliefs and attitudes about sleep all associated with their children's sleep quality, and with the sleep subdomains of sleep anxiety and parasomnias. In multiple regression analysis only parental insomnia score was a significant predictor of children's sleep quality. Children's bedtimes, wake times, sleep duration, chronotype or social jetlag did not associate with parents' ADHD or insomnia symptoms. Sleep quality was significantly poorer in children whose parents scored as both consistent for adult ADHD and probable for insomnia disorder compared to parents who scored as either ADHD consistent or insomnia probable, or those who parents scored as neither. We discuss the putative nature of the relationships between sleep quality of children with ADHD and parental ADHD and insomnia symptoms, and suggest that clinicians consider parental sleep when attending to children with ADHD.

Development of the Parenting Behavior Checklist to Promote Preschoolers' Sleep (PCPP)

OBJECTIVES

To develop the Parenting Behavior Checklist to Promote Preschoolers' sleep (PCPP), quantify sleep-promoting parenting behaviors for children, and examine the scale's reliability and validity.

METHODS

The PCPP was developed based on the recommendations of the ABCs of SLEEPING for children's sleep, which is strongly supported by research evidence. Its validity and reliability were evaluated using data from 140 participants. Structural validity was estimated using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), and internal consistency was evaluated by Cronbach's α. Hypothesis testing was evaluated by analyzing the correlations between each factor of the Japanese Sleep Questionnaire for Preschoolers (JSQ-P) and the PCPP.

RESULTS

Regarding structural validity, EFA was conducted because CFA showed a poor model fit. The PCPP comprised one factor and six items. The JSQ-P subfactors of insomnia or circadian rhythm sleep-wake disorders, undesirable morning symptoms and behaviors, and insufficient sleep were moderately negatively correlated with the PCPP; the subfactor of undesirable daytime behaviors related to sleep problems was weakly negatively correlated with the PCPP. Thus, the sleep-promoting parenting behaviors listed in the PCPP were associated with better sleep in children.

CONCLUSIONS

The PCPP showed sufficient reliability and validity. Future studies should use the scale to examine more effective interventions regarding sleep-promoting parental behaviors for children.

Understanding zebrafish sleep and wakefulness physiology as an experimental model for biomedical research

Sleep is a globally observable fact, or period of reversible distracted rest, that can be distinguished from arousal by various behavioral criteria. Although the function of sleep is an evolutionarily conserved behavior, its mechanism is not yet clear. The zebrafish (Danio rerio) has become a valuable model for neurobehavioral studies such as studying learning, memory, anxiety, and depression. It is characterized by a sleep-like state and circadian rhythm, making it comparable to mammals. Zebrafish are a good model for behavioral studies because they share genetic similarities with humans. A number of neurotransmitters are involved in sleep and wakefulness. There is a binding between melatonin and the hypocretin system present in zebrafish. The full understanding of sleep and wakefulness physiology in zebrafish is still unclear among researchers. Therefore, to make a clear understanding of the sleep/wake cycle in zebrafish, this article covers the mechanism involved behind it, and the role of the neuromodulator system followed by the mechanism of the HPA axis.

ADHD in narcolepsy: A closer look at prevalence and ties

The reported prevalence of attention deficit hyperactivity disorder (ADHD) in narcolepsy varies considerably, while the associated factors remain inadequately established. A systematic search of studies published in PubMed, EMBASE, and the Cochrane Library was performed from inception to March 2023. Ten studies with 839 patients with narcolepsy were included in the study. Utilizing a random effects model, the pooled prevalence of ADHD in narcolepsy was 25% (95% CI, 14-38%). Notably, patients with narcolepsy type 2 showed a significantly higher prevalence of ADHD than that of narcolepsy type 1 (46% vs. 20%, p = 0.045). Furthermore, the rate of ADHD was notably elevated in narcolepsy compared with the healthy controls (odds ratio 9.59, 95% CI, 4.06-22.63, p < 0.001). Several factors such as excessive daytime sleepiness (EDS), fatigue, insomnia severity, and the quality of life were significantly associated with ADHD in narcolepsy (all ps < 0.05). These findings highlight the importance of monitoring and managing ADHD in narcolepsy, and provide a clue to help reducing ADHD by intervening in these associated factors.

Narcolepsy and psychiatric disorders: A bidirectional Mendelian randomization study

Since the introduction of the concept of narcolepsy, there has been a proliferation of discussions about its association with psychiatry. To elucidate the causal role of narcolepsy in the three psychiatric disorders [i.e., schizophrenia (SCZ), major depressive disorder (MDD), and attention-deficit hyperactivity disorder (ADHD)], we applied a bidirectional Mendelian randomization study using two stages (discovery stage and validation stage) and data from three different genome-wide association studies of narcolepsy. The estimates from different stages were combined using fixed-effects meta-analysis. Our findings suggest that narcolepsy is associated with an increased risk of SCZ. Conversely, MDD may be causally related to narcolepsy. A causal relationship between narcolepsy and ADHD was excluded.

Interaction of genetic liability for attention deficit hyperactivity disorder (ADHD) and perinatal inflammation contributes to ADHD symptoms in children

Objective

Genetic and environmental factors contribute to the development of Attention Deficit/Hyperactivity Disorder (ADHD). Perinatal inflammation is one of the promising environmental risk factors for ADHD, but the relationship between the genetic risk for ADHD and perinatal inflammation requires further examination.

Methods

A possible gene-environmental interaction between perinatal inflammation and ADHD polygenic risk score (ADHD-PRS) on ADHD symptoms was investigated in children aged 8-9 from the Hamamatsu Birth Cohort for Mothers and Children (N = 531). Perinatal inflammation was evaluated by the level of concentration of three cytokines assayed in umbilical cord blood. The genetic risk for ADHD was assessed by calculating ADHD-PRS for each individual using a previously collected genome-wide association study of ADHD.

Results

Perinatal inflammation (β [SE], 0.263 [0.017]; P < 0.001), ADHD-PRS (β [SE], 0.116[0.042]; P = 0.006), and an interaction between the two (β [SE], 0.031[0.011]; P = 0.010) were associated with ADHD symptoms. The association between perinatal inflammation and ADHD symptoms measured by ADHD-PRS was evident only in the two higher genetic risk groups (β [SE], 0.623[0.122]; P < 0.001 for the medium-high risk group; β [SE], 0.664[0.152]; P < 0.001 for the high-risk group).

Conclusion

Inflammation in the perinatal period both directly elevated ADHD symptoms and magnified the impact of genetic vulnerability on ADHD risk particularly among children aged 8-9 with genetically higher risk for ADHD.

Genome-wide association study reveals ethnicity-specific SNPs associated with ankylosing spondylitis in the Taiwanese population

BACKGROUND

Ankylosing spondylitis (AS) is an autoimmune disease affecting mainly spine and sacroiliac joints and adjacent soft tissues. Genome-wide association studies (GWASs) are used to evaluate genetic associations and to predict genetic risk factors that determine the biological basis of disease susceptibility. We aimed to explore the race-specific SNP susceptibility of AS in Taiwanese individuals and to investigate the association between HLA-B27 and AS susceptibility SNPs in Taiwan.

METHODS

Genotyping data were collected from a medical center participating in the Taiwan Precision Medicine Initiative (TPMI) in the northern district of Taiwan. We designed a case-control study to identify AS susceptibility SNPs through GWAS. We searched the genome browser to find the corresponding susceptibility genes and used the GTEx database to confirm the regulation of gene expression. A polygenic risk score approach was also applied to evaluate the genetic variants in the prediction of developing AS.

RESULTS

The results showed that the SNPs located on the sixth chromosome were related to higher susceptibility in the AS group. There was no overlap between our results and the susceptibility SNPs found in other races. The 12 tag SNPs located in the MHC region that were found through the linkage disequilibrium method had higher gene expression. Furthermore, Taiwanese people with HLA-B27 positivity had a higher proportion of minor alleles. This might be the reason that the AS prevalence is higher in Taiwan than in other countries. We developed AS polygenic risk score models with six different methods in which those with the top 10% polygenic risk had a fivefold increased risk of developing AS compared to the remaining group with low risk.

CONCLUSION

A total of 147 SNPs in the Taiwanese population were found to be statistically significantly associated with AS on the sixth pair of chromosomes and did not overlap with previously published sites in the GWAS Catalog. Whether those genes mapped by AS-associated SNPs are involved in AS and what the pathogenic mechanism of the mapped genes is remain to be further studied.

Dissecting the Polygenic Basis of Primary Hypertension: Identification of Key Pathway-Specific Components

Introduction and Objectives

Genome-wide association studies have identified a high number of genetic loci associated with hypertension suggesting the presence of an underlying polygenic architecture. In this study, we aimed to dissect the polygenic component of primary hypertension searching also for pathway-specific components.

Methods

The polygenic risk score (PRS) models, based on the UK biobank genetic signals for hypertension status, were obtained on a target Italian case/control cohort including 561 cases and 731 hyper-normal controls from HYPERGENES, and were then applied to an independent validation cohort composed by multi-countries European-based samples including 1,284 cases and 960 hyper-normal controls.

Results

The resulting genome-wide PRS was capable of stratifying the individuals for hypertension risk by comparing between individuals in the last PRS decile and the median decile: we observed an odds ratio (OR) of 3.62, CI = [2.01, 6.32] (P = 9.01E-07) and 3.22, 95% CI = [2.06, 5.10] (P = 6.47E-08) in the target and validation cohorts, respectively. The relatively high case/control ORs across PRS quantiles corroborates the presence of strong polygenic components which could be driven by an enrichment of risk alleles within the cases but also by potential enrichment of protective alleles in the old normotensive controls. Moreover, novel pathway-specific PRS revealed an enrichment of the polygenic signal attributable to specific biological pathways. Among those the most significantly associated with hypertension status was the calcium signaling pathway together with other mainly related such as the phosphatidylinositol/inositol phosphate pathways.

Conclusions

The development of pathway-specific PRS could prioritize biological mechanisms, according to their contribution to the genetic susceptibility, whose regulations might be a potential pharmacological preventive target.

Attention-Deficit/Hyperactivity Disorder, Insomnia, and Sleepiness Symptoms among a Community Adult Sample: The Mediating Effect of Executive Behavioral Regulation and Metacognition Abilities

OBJECTIVE

Adult attention-deficit/hyperactivity disorder (ADHD) is characterized by a dysexecutive syndrome reflected in cognitive, emotional, and behavioral areas. Independently of a formal diagnosis of ADHD, higher ADHD symptoms are associated with higher levels of insomnia and sleepiness symptoms in adult population-based samples. Insomnia and sleepiness are sleep disorders that are both associated with deficits in several aspects of executive functions which in turn are likely to mimic a range of ADHD symptoms. Our objective was to explore the interrelationships between ADHD, insomnia, and sleepiness symptoms and executive functioning in community-dwelling adults.

METHOD

A total of 442 participants (18-89 years, 56% females) underwent a semistructured clinical interview and completed questionnaires for insomnia, sleepiness, and everyday behaviors in which executive functions are implicated. Mediation Models were applied.

RESULTS

Insomnia and sleepiness symptoms did not play a mediating role between ADHD symptoms and executive functioning. Conversely, our results highlighted a mediating effect of daytime insomnia consequences and sleepiness on ADHD symptoms via behavioral regulation executive symptoms (respectively, β = -0.32, p < .001, 95% CI [-0.46, -0.20]; β = 0.09, p < .05, 95% CI [0.02, 0.16]) and metacognitive executive symptoms (respectively, β = -0.30, p < .001, 95% CI [-0.44, -0.18]; β = 0.12, p < .01, 95% CI [0.04, 0.22]).

CONCLUSIONS

Daytime insomnia consequences and sleepiness symptoms could lead to ADHD-like symptoms through their associated executive symptoms expressed in daily life. When faced with symptoms suggestive of ADHD in adults, insomnia and sleepiness should be systematically screened with standardized instruments.

Association of Epigenetic Differences Screened in a Few Cases of Monozygotic Twins Discordant for Attention-Deficit Hyperactivity Disorder With Brain Structures

The present study examined the relationship between DNA methylation differences and variations in brain structures involved in the development of attention-deficit hyperactivity disorder (ADHD). First, we used monozygotic (MZ) twins discordant (2 pairs of 4 individuals, 2 boys, mean age 12.5 years) for ADHD to identify candidate DNA methylation sites involved in the development of ADHD. Next, we tried to replicate these candidates in a case-control study (ADHD: N = 18, 15 boys, mean age 10.0 years; Controls: N = 62, 40 boys, mean age 13.9 years). Finally, we examined how methylation rates at those sites relate to the degree of local structural alterations where significant differences were observed between cases and controls. As a result, we identified 61 candidate DNA methylation sites involved in ADHD development in two pairs of discordant MZ twins, among which elevated methylation at a site in the sortilin-related Vps10p domain containing receptor 2 (SorCS2) gene was replicated in the case-control study. We also observed that the ADHD group had significantly reduced gray matter volume (GMV) in the precentral and posterior orbital gyri compared to the control group and that this volume reduction was positively associated with SorCS2 methylation. Furthermore, the reduced GMV regions in children with ADHD are involved in language processing and emotional control, while SorCS2 methylation is also negatively associated with emotional behavioral problems in children. These results indicate that SorCS2 methylation might mediate a reduced GMV in the precentral and posterior orbital gyri and therefore influence the pathology of children with ADHD.

Decoupling Sleep and Brain Size in Childhood: An Investigation of Genetic Covariation in the Adolescent Brain Cognitive Development Study

Background

Childhood sleep problems are common and among the most frequent and impairing comorbidities of childhood psychiatric disorders. In adults, sleep disturbances are heritable and show strong genetic associations with brain morphology; however, little is known about the genetic architecture of childhood sleep and potential etiological links between sleep, brain development, and pediatric-onset psychiatric symptoms.

Methods

Using data from the Adolescent Brain Cognitive Development Study (n _Phenotype = 4428 for discovery/replication, n _Genetics = 4728; age 9-10 years), we assessed phenotypic relationships, heritability, and genetic correlations between childhood sleep disturbances (insomnia, arousal, breathing, somnolence, hyperhidrosis, sleep-wake transitions), brain size (surface area, cortical thickness, volume), and dimensional psychopathology.

Results

Sleep disturbances showed widespread positive associations with multiple domains of childhood psychopathology; however, only insomnia showed replicable associations with smaller brain surface area. Among the sleep disturbances assessed, only insomnia showed significant heritability (h ² _SNP = 0.15, p < .05) and showed substantial genetic correlations with externalizing and attention-deficit/hyperactivity disorder symptomatology (r _G s > 0.80, ps < .05). We found no evidence of genetic correlation between childhood insomnia and brain size. Furthermore, polygenic risk scores calculated from genome-wide association studies of adult insomnia and adult brain size did not predict childhood insomnia; instead, polygenic risk scores trained using attention-deficit/hyperactivity disorder genome-wide association studies predicted decreased surface area at baseline as well as insomnia and externalizing symptoms longitudinally.

Conclusions

Findings demonstrate a distinct genetic architecture underlying childhood insomnia and brain size and suggest genetic overlap between childhood insomnia and attention-deficit/hyperactivity disorder symptomatology. Additional research is needed to examine how genetic risk manifests in altered developmental trajectories and comorbid sleep/psychiatric symptoms across adolescence.

Sleep disturbances in ADHD: investigating the contribution of polygenic liability for ADHD and sleep-related phenotypes

Sleep disturbances are common in attention deficit hyperactivity disorder (ADHD) and associated with poor outcomes. We tested whether, in children with ADHD, (1) polygenic liability for sleep phenotypes is over- or under-transmitted from parents, (2) this liability is linked to comorbid sleep disturbances, and (3) ADHD genetic risk is associated with comorbid sleep disturbances. We derived polygenic scores (PGS) for insomnia, chronotype, sleep duration, and ADHD, in 758 children (5-18 years old) diagnosed with ADHD and their parents. We conducted polygenic transmission disequilibrium tests for each sleep PGS in complete parent-offspring ADHD trios (N = 328) and an independent replication sample of ADHD trios (N = 844). Next, we tested whether insomnia, sleep duration, and ADHD PGS were associated with co-occurring sleep phenotypes (hypersomnia, insomnia, restless sleep, poor sleep quality, and nightmares) in children with ADHD. Children's insomnia and chronotype PGS did not differ from mid-parent average PGS but long sleep duration PGS were significantly over-transmitted to children with ADHD. This was supported by a combined analysis using the replication sample. Insomnia, sleep duration, and ADHD PGS were not associated with comorbid sleep disturbances. There is weak evidence that children with ADHD over-inherit polygenic liability for longer sleep duration and do not differentially inherit polygenic liability for insomnia or chronotype. There was insufficient evidence that childhood sleep disturbances were driven by polygenic liability for ADHD or sleep traits, suggesting that sleep disturbances in ADHD may be aetiologically different to general population sleep phenotypes and do not index greater ADHD genetic risk burden.

Orexin/Hypocretin System Dysfunction in ESSENCE (Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations)

Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations (ESSENCE) is an umbrella term covering a wide range of neurodevelopmental difficulties and disorders. Thus, ESSENCE includes attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and other neurodevelopmental disorders (NDDs) and difficulties, with a variety of symptoms in cognitive, motor, sensory, social, arousal, regulatory, emotional, and behavioral developmental domains, frequently co-occurring and likely having partly common neurobiological substrates. The ESSENCE concept is a clinical paradigm that promotes organizing NDDs in everyday clinical practice according to their coexistence, symptom dimensions overlapping, and treatment possibilities. Despite increased knowledge regarding NDDs, the neurobiological mechanisms that underlie them and other ESSENCE-related problems, are not well understood. With its wide range of neural circuits and interactions with numerous neurotransmitters, the orexin/hypocretin system (Orx-S) is possibly associated with a variety of neurocognitive, psychobiological, neuroendocrine, and physiological functions and behaviors. Dysfunction of Orx-S has been implicated in various psychiatric and neurological disorders. This article provides an overview of Orx-S dysfunctions' possible involvement in the development, presentation, and maintenance of ESSENCE. We provide a focused review of current research evidence linking orexin neuropeptides with specific clinical NDDs symptoms, mostly in ADHD and ASD, within the Research Domain Criteria (RDoC) framework. We propose that Orx-S dysfunction might have an important role in some of these neurodevelopmental symptom domains, such as arousal, wakefulness, sleep, motor and sensory processing, mood and emotional regulation, fear processing, reward, feeding, attention, executive functions, and sociability. Our perspective is presented from a clinical point of view. Further, more thorough systematic reviews are needed as well as planning of extensive new research into the Orx-S's role in ESSENCE, especially considering RDoC elements.

Polygenic risk of genes involved in the catecholamine and serotonin pathways for ADHD in children

It is general acknowledged that genes play a vital role in the etiology of attention deficit/hyperactivity disorder (ADHD). The relationship between the genes involved in catecholamine (dopamine, noradrenaline)/serotonin transmissions and ADHD has been widely described in medical literature. A pathway-based study was conducted in this study to test the association of gene-gene interaction and the cumulative effect of genetic polymorphisms within the dopamine, norepinephrine, and serotonin neurotransmitter pathways with ADHD susceptibility. A case-control study was conducted among Chinese children, and 168 ADHD patients and 233 controls were recruited using a combination diagnosis according to the DSM-IV ADHD rating scale. Classification and regression tree (CART) analysis was conducted to explore the gene-gene interaction, and logistic regression modal was applied to estimate the polygenic risk of the potential multiple genetic variants. The results of CART analyses indicated that the children carrying the combination of ADRA2A rs553668GG/GA and SLC6A4 rs6354 GG/GT genotypes displayed a 6.15-fold increased risk of ADHD, compared to those with the combination of ADRA2A rs553668 AA and ANKK1 rs1800497 AA genotypes. The unfavorable alleles of ADRA2A rs553668 G, DRD2 rs1124491 G and SLC6A4 rs6354 G showed cumulative effects on ADHD, and the OR for ADHD may increase by 1.42 times when the number of unfavorable allele number increased by one. Those findings reveal the importance of the gene-gene interactions and polygenic effects of many common variants to ADHD susceptibility, even the effect of each variant is very small.