Hidden in plain sight: delayed ADHD diagnosis among girls and women - a commentary on Skoglund et al. (2023).

Skoglund et al. (Journal of Child Psychology and Psychiatry, 2023) finds women with ADHD experience a nearly 4-year delay in receiving an ADHD diagnosis compared to men, despite also having high rates of prior contact with the mental health care system. In this commentary, I discuss the findings of Skoglund et al. and how they shed light on possible explanations for this diagnostic delay among women, and the need to consider women-specific issues, like times of hormonal change, in ADHD diagnosis and treatment.

Do Children With Attention-Deficit/Hyperactivity Disorder Symptoms Become Socially Isolated? Longitudinal Within-Person Associations in a Nationally Representative Cohort.

Objective: This study examined longitudinal associations between attention-deficit/hyperactivity disorder (ADHD) symptoms and social isolation across childhood. The study tested the direction of this association across time, while accounting for preexisting characteristics, and assessed whether this association varied by ADHD presentation, informant, sex, and socioeconomic status. Method: Participants included 2,232 children from the Environmental Risk (E-Risk) Longitudinal Twin Study. ADHD symptoms and social isolation were measured at ages 5, 7, 10, and 12. Random-intercept cross-lagged panel models were used to assess the directionality of the association across childhood. Results: Children with increased ADHD symptoms were consistently at increased risk of becoming socially isolated later in childhood, over and above stable characteristics (ß = .05-.08). These longitudinal associations were not bidirectional; isolated children were not at risk of worsening ADHD symptoms later on. Children with hyperactive ADHD presentation were more likely to become isolated, compared with inattentive presentation. This was evident in the school setting, as observed by teachers, but not by mothers at home. Conclusion: The study findings highlight the importance of enhancing peer social support and inclusion for children with ADHD, particularly in school settings. This study adds explanatory value beyond traditional longitudinal methods, as the results represent how individual children change over time, relative to their own preexisting characteristics. Diversity & Inclusion Statement: We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. We actively worked to promote sex and gender balance in our author group. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work.

A meta-analysis of genetic effects associated with neurodevelopmental disorders and co-occurring conditions.

A systematic understanding of the aetiology of neurodevelopmental disorders (NDDs) and their co-occurrence with other conditions during childhood and adolescence remains incomplete. In the current meta-analysis, we synthesized the literature on (1) the contribution of genetic and environmental factors to NDDs, (2) the genetic and environmental overlap between different NDDs, and (3) the co-occurrence between NDDs and disruptive, impulse control and conduct disorders (DICCs). Searches were conducted across three platforms: Web of Science, Ovid Medline and Ovid Embase. Studies were included only if 75% or more of the sample consisted of children and/or adolescents and the studies had measured the aetiology of NDDs and DICCs using single-generation family designs or genomic methods. Studies that had selected participants on the basis of unrelated diagnoses or injuries were excluded. We performed multilevel, random-effects meta-analyses on 296 independent studies, including over four million (partly overlapping) individuals. We further explored developmental trajectories and the moderating roles of gender, measurement, geography and ancestry. We found all NDDs to be substantially heritable (family-based heritability, 0.66 (s.e. = 0.03); SNP heritability, 0.19 (s.e. = 0.03)). Meta-analytic genetic correlations between NDDs were moderate (grand family-based genetic correlation, 0.36 (s.e. = 0.12); grand SNP-based genetic correlation, 0.39 (s.e. = 0.19)) but differed substantially between pairs of disorders. The genetic overlap between NDDs and DICCs was strong (grand family-based genetic correlation, 0.62 (s.e. = 0.20)). While our work provides evidence to inform and potentially guide clinical and educational diagnostic procedures and practice, it also highlights the imbalance in the research effort that has characterized developmental genetics research.

Taking stock of the present and looking to the future of ADHD research: a commentary on Sonuga-Barke et al. (2023).

The review by Sonuga-Barke and colleagues offers a thoughtful and wide-ranging appraisal of the current state of ADHD research, while also looking into the future to consider unresolved questions and critical next steps. Furthermore, it grapples with the tension between the need to define a coherent conceptualisation of ADHD for clinical and research purposes, while keeping an open mind to new research that challenges current consensus. In our commentary, we consider several cross-cutting ideas discussed in Sonuga-Barke et al., including the heterogeneous nature of ADHD, ensuring equity of translational research, and the importance of participatory research to support equitable and acceptable clinical practices for all individuals with ADHD.

Is quality of life related to high autistic traits, high ADHD traits and their Interaction? Evidence from a Young-Adult Community-Based twin sample.

This study explored whether high autistic traits, high attention deficit hyperactivity disorder (ADHD) traits and their interaction were associated with quality of life (QoL) in a sample of 556 of young-adult twins (Mean age 22 years 5 months, 52% Female). Four participant groups were created: high autistic traits, high ADHD traits, high autistic/ADHD traits, and low ADHD/autistic traits. High autistic traits were associated with lower QoL across domains (physical, psychological, social, and environmental). High ADHD traits associated with lower physical, psychological, and environmental QoL. The interaction of autistic and ADHD traits was not significant in any domain. While mental health difficulties were associated with lower QoL, after accounting for mental health, most relationships between autistic traits, ADHD traits and QoL remained.

Mother's and children's ADHD genetic risk, household chaos and children's ADHD symptoms: A gene-environment correlation study.

BACKGROUND: Chaotic home environments may contribute to children's attention-deficit hyperactivity disorder (ADHD) symptoms. However, ADHD genetic risk may also influence household chaos. This study investigated whether children in chaotic households had more ADHD symptoms, if mothers and children with higher ADHD genetic risk lived in more chaotic households, and the joint association of genetic risk and household chaos on the longitudinal course of ADHD symptoms across childhood. METHODS: Participants were mothers and children from the Environmental Risk (E-Risk) Longitudinal Twin Study, a UK population-representative birth cohort of 2,232 twins. Children's ADHD symptoms were assessed at ages 5, 7, 10 and 12 years. Household chaos was rated by research workers at ages 7, 10 and 12, and by mother's and twin's self-report at age 12. Genome-wide ADHD polygenic risk scores (PRS) were calculated for mothers (n = 880) and twins (n = 1,999); of these, n = 871 mothers and n = 1,925 children had information on children's ADHD and household chaos. RESULTS: Children in more chaotic households had higher ADHD symptoms. Mothers and children with higher ADHD PRS lived in more chaotic households. Children's ADHD PRS was associated with household chaos over and above mother's PRS, suggesting evocative gene-environment correlation. Children in more chaotic households had higher baseline ADHD symptoms and a slower rate of decline in symptoms. However, sensitivity analyses estimated that gene-environment correlation accounted for a large proportion of the association of household chaos on ADHD symptoms. CONCLUSIONS: Children's ADHD genetic risk was independently associated with higher levels of household chaos, emphasising the active role of children in shaping their home environment. Our findings suggest that household chaos partly reflects children's genetic risk for ADHD, calling into question whether household chaos directly influences children's core ADHD symptoms. Our findings highlight the importance of considering parent and child genetic risk in relation to apparent environmental exposures.

Decline in attention-deficit hyperactivity disorder traits over the life course in the general population: trajectories across five population birth cohorts spanning ages 3 to 45 years.

BACKGROUND: Trajectories of attention-deficit hyperactivity disorder (ADHD) traits spanning early childhood to mid-life have not been described in general populations across different geographical contexts. Population trajectories are crucial to better understanding typical developmental patterns. METHODS: We combined repeated assessments of ADHD traits from five population-based cohorts, spanning ages 3 to 45 years. We used two measures: (i) the Strengths and Difficulties Questionnaire (SDQ) hyperactive-inattentive subscale (175 831 observations, 29 519 individuals); and (ii) scores from DSM-referenced scales (118 144 observations, 28 685 individuals). Multilevel linear spline models allowed for non-linear change over time and differences between cohorts and raters (parent/teacher/self). RESULTS: Patterns of age-related change differed by measure, cohort and country: overall, SDQ scores decreased with age, most rapidly declining before age 8 years (-0.157, 95% CI: -0.170, -0.144 per year). The pattern was generally consistent using DSM scores, although with greater between-cohort variation. DSM scores decreased most rapidly between ages 14 and 17 years (-1.32%, 95% CI: -1.471, -1.170 per year). Average scores were consistently lower for females than males (SDQ: -0.818, 95% CI: -0.856, -0.780; DSM: -4.934%, 95% CI: -5.378, -4.489). This sex difference decreased over age for both measures, due to an overall steeper decrease for males. CONCLUSIONS: ADHD trait scores declined from childhood to mid-life, with marked variation between cohorts. Our results highlight the importance of taking a developmental perspective when considering typical population traits. When interpreting changes in clinical cohorts, it is important to consider the pattern of expected change within the general population, which is influenced by cultural context and measurement.

"Late-onset" ADHD symptoms in young adulthood: Is this ADHD?

Objective: We investigated whether "late-onset" ADHD that emerges in adolescence/adulthood is similar in risk factor profile to: (1) child-onset ADHD, but emerges later because of scaffolding/compensation from childhood resources; and (2) depression, because it typically onsets in adolescence/adulthood and shows symptom and genetic overlaps with ADHD. Methods: We examined associations between late-onset ADHD and ADHD risk factors, cognitive tasks, childhood resources and depression risk factors in a population-based cohort followed-up to age 25 years (N=4224-9764). Results: Parent-rated late-onset ADHD was like child-onset persistent ADHD in associations with ADHD polygenic risk scores and cognitive task performance, although self-rated late-onset ADHD was not. Late-onset ADHD was associated with higher levels of childhood resources than child-onset ADHD and did not show strong evidence of association with depression risk factors. Conclusions: Late-onset ADHD shares characteristics with child-onset ADHD when parent-rated, but differences for self-reports require investigation. Childhood resources may delay the onset of ADHD.

COVID-19 and Perceived Changes to Quality of Life, Anxiety, Depression, and Loneliness in Autistic and Other Neurodivergent U.K. Adults.

Background: In the United Kingdom, we have experienced many changes to our daily lives as a result of COVID-19. Autistic and other neurodivergent (ND, e.g., those with attention-deficit hyperactivity disorder) adults may be more vulnerable to negative effects of the pandemic due to pre-existing mental health disparities and unmet support needs. Furthermore, there is little research, either pandemic related or otherwise, which considers how the experiences of autistic adults with additional intersecting ND identities might differ from those without. Methods: We collected data from an online survey during June 2020 to September 2020 to explore the psychological impact of the coronavirus pandemic on U.K. adults (N = 286, age 18-72 years). Participants included neurotypical (NT) adults (N = 98), autistic adults (N = 73), other ND adults (N = 53), as well as autistic adults with an additional intersecting ND identity (N = 63). We measured and compared levels of quality of life (QoL), depression, anxiety, and loneliness across groups as well as perceived change in these as a result of the pandemic. Results: Autistic adults, with and without additional ND identities, had consistently low QoL and high anxiety, depression, and loneliness compared with NT adults. We found no differences in these areas between autistic adults with and without additional intersecting ND identities. In some areas, non-autistic ND participants were also doing poorly compared with their NT peers. Many participants felt that their QoL, mental health, and loneliness had worsened due to the pandemic, and this was largely similar across groups. Conclusions: These results highlight that COVID-19 may have led to increased need and demand for mental health services across the U.K. adult population. Both autistic and ND adults may be in particular need of increased (and improved) mental health and well-being support. This is likely because of pre-existing differences in mental health and well-being as well as individuals facing further difficulties as a result of the pandemic.

Why is this an important issue? The coronavirus pandemic has been difficult for many people. Some researchers have found that the pandemic may have been especially difficult for autistic adults and those who are neurodivergent in another way. This might be because autistic and neurodivergent people often experience poor mental health and have a variety of unmet needs. What was the purpose of this study? The purpose of this study was to explore quality of life, depression, anxiety, and loneliness in different groups of adults during the pandemic. We also wanted to explore whether people felt that these had become worse during the pandemic. We were interested to explore differences between autistic adults and other groups of neurodivergent adults. This included autistic adults, autistic adults who were neurodivergent in another way, non-autistic neurodivergent adults, and a comparison group of adults who were not autistic or neurodivergent in any way. What did the researchers do? We recruited participants to take part in an online survey during June 2020 to September 2020. We advertised the study using social media and research websites. A total of 286 adults from the United Kingdom completed our survey. What were the results of the study? Autistic adults had consistently low quality of life and high anxiety, depression, and loneliness compared with the comparison group. This was the same regardless of whether the autistic adults were neurodivergent in another way too. In some areas, non-autistic neurodivergent participants had lower quality of life than the comparison group. Their depression and loneliness scores were somewhere in between autistic participants' and the comparison group's. Many participants felt that their quality of life, mental health, and loneliness had worsened due to the pandemic. This was similar for participants in all the groups. However, there were also participants who felt much better due to coronavirus restrictions. What do these findings add to what was already known? We now know that autistic adults have experienced poor quality of life, mental health, and loneliness during the pandemic. We also found that there were no differences based on whether autistic adults were also neurodivergent in another way (e.g., an autistic adult with attention-deficit hyperactivity disorder). We also know that non-autistic neurodivergent adults have experienced low quality of life during this time. This is important because there has been very little research on other non-autistic neurodivergent adults' experiences during COVID-19 restrictions. What are potential weaknesses in the study? Most of our participants were white British and female. This means that our findings may not be relevant to all adults in the United Kingdom. Our study was carried out during the pandemic, which means that we do not know if these differences between the groups will continue to be true in the future. How will these findings help autistic adults now or in the future? We hope that these findings will help to argue for more support to be made available to promote good quality of life and reduce mental health difficulties for autistic, and other neurodivergent, adults. Lots of our participants felt that their quality of life and mental health had got worse due to the pandemic. Because of this, it is now even more important that governments make changes to policy and funding to provide better services and support for autistic and neurodivergent adults.

Bullying behaviours and other conduct problems: longitudinal investigation of their independent associations with risk factors and later outcomes.

PURPOSE: Bullying behaviours and other conduct problems often co-occur. However, we do not yet know whether bullying behaviours are associated with early factors and later poor outcomes independently of conduct problems. While there are differing, specific interventions for bullying behaviours and for conduct problems, it is unclear if such specificity is justified given parallels between both behaviours. METHODS: We used prospective data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative sample of 2232 children. Mothers and teachers reported on children's bullying behaviours and conduct problems at ages 7 and 10. We collected measures of risk factors, including temperament and family factors, when children were age 5. We assessed behavioural, emotional, educational and social problems when participants reached the ages of 12 and 18. RESULTS: Bullying behaviours and conduct problems co-occurred in childhood. Our findings indicated that bullying behaviours and other conduct problems were independently associated with the same risk factors. Furthermore, they were associated with the same poor outcomes at both ages 12 and 18. Despite this, bullying behaviours were uniquely associated with behavioural, emotional, educational and social problems at age 18. CONCLUSIONS: Our findings suggest that anti-bullying programmes and interventions aimed at reducing conduct problems could benefit from greater integration. Furthermore, our study highlights the mental health problems children who bully may face in later years and the need to consider those in intervention plans.

Polygenic Risk and the Course of Attention-Deficit/Hyperactivity Disorder From Childhood to Young Adulthood: Findings From a Nationally Representative Cohort.

OBJECTIVE: To understand whether genetic risk for attention-deficit/hyperactivity disorder (ADHD) is associated with the course of the disorder across childhood and into young adulthood. METHOD: Participants were from the Environmental Risk (E-Risk) Longitudinal Twin Study, a population-based birth cohort of 2,232 twins. ADHD was assessed at ages 5, 7, 10, and 12 with mother- and teacher-reports and at age 18 with self-report. Polygenic risk scores (PRSs) were created using a genome-wide association study of ADHD case status. Associations with PRS were examined at multiple points in childhood and longitudinally from early childhood to adolescence. We investigated ADHD PRS and course to young adulthood, as reflected by ADHD remission, persistence, and late onset. RESULTS: Participants with higher ADHD PRSs had increased risk for meeting ADHD diagnostic criteria (odds ratios ranging from 1.17 at age 10 to 1.54 at age 12) and for elevated symptoms at ages 5, 7, 10, and 12. Higher PRS was longitudinally associated with more hyperactivity/impulsivity (incidence rate ratio = 1.18) and inattention (incidence rate ratio = 1.14) from age 5 to age 12. In young adulthood, participants with persistent ADHD exhibited the highest PRS (mean PRS = 0.37), followed by participants with remission (mean PRS = 0.21); both groups had higher PRS than controls (mean PRS = -0.03), but did not significantly differ from one another. Participants with late-onset ADHD did not show elevated PRS for ADHD, depression, alcohol dependence, or marijuana use disorder. CONCLUSION: Genetic risk scores derived from case-control genome-wide association studies may have relevance not only for incidence of mental health disorders, but also for understanding the longitudinal course of mental health disorders.

Associations between ADHD and emotional problems from childhood to young adulthood: a longitudinal genetically sensitive study.

BACKGROUND: Attention deficit/hyperactivity disorder (ADHD) is associated with emotional problems, and their co-occurrence often leads to worse outcomes. We investigated the developmental associations between ADHD and emotional problems from childhood to early adolescence and examined the genetic and environmental contributions to their developmental link. We further tested whether this developmental association remained across the transition to young adulthood. METHODS: We used data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a cohort of 2,232 British twins. In childhood, ADHD and emotional problems were assessed at ages 5, 7, 10 and 12 with mothers' and teachers' reports. At age 18, we used self-reported symptoms according to DSM-5 criteria for ADHD, and DSM-IV for anxiety and depression. RESULTS: Longitudinal analyses showed that earlier ADHD was associated with later emotional problems consistently across childhood. However, earlier emotional problems were not associated with later ADHD symptoms. The developmental association between ADHD and later emotional problems in childhood was entirely explained by common genetic factors. Consistent with results in childhood, earlier symptoms of ADHD were associated with later emotional problems during the transition to young adulthood. CONCLUSIONS: Our findings demonstrate that ADHD symptoms are predictors of the development of emotional problems, from childhood up to young adulthood, through shared genetic influences. Interventions targeting ADHD symptoms might prevent the development of emotional problems. Clinicians treating youth with ADHD must be aware of their risk for developing emotional problems and ought to assess, monitor and treat emotional problems alongside ADHD symptoms from childhood to adulthood.

Using DNA From Mothers and Children to Study Parental Investment in Children's Educational Attainment.

This study tested implications of new genetic discoveries for understanding the association between parental investment and children's educational attainment. A novel design matched genetic data from 860 British mothers and their children with home-visit measures of parenting: the E-Risk Study. Three findings emerged. First, both mothers' and children's education-associated genetics, summarized in a genome-wide polygenic score, were associated with parenting-a gene-environment correlation. Second, accounting for genetic influences slightly reduced associations between parenting and children's attainment-indicating some genetic confounding. Third, mothers' genetics were associated with children's attainment over and above children's own genetics, via cognitively stimulating parenting-an environmentally mediated effect. Findings imply that, when interpreting parents' effects on children, environmentalists must consider genetic transmission, but geneticists must also consider environmental transmission.

Are changes in ADHD course reflected in differences in IQ and executive functioning from childhood to young adulthood?

BACKGROUND: Attention-deficit hyperactivity disorder (ADHD) is associated with poorer cognitive functioning. We used a developmental, genetically-sensitive approach to examine intelligence quotient (IQ) from early childhood to young adulthood among those with different ADHD courses to investigate whether changes in ADHD were reflected in differences in IQ. We also examined executive functioning in childhood and young adulthood among different ADHD courses. METHODS: Study participants were part of the Environmental Risk (E-Risk) Longitudinal Twin Study, a population-based birth cohort of 2232 twins. We assessed ADHD in childhood (ages 5, 7, 10 and 12) and young adulthood (age 18). We examined ADHD course as reflected by remission, persistence and late-onset. IQ was evaluated at ages 5, 12 and 18, and executive functioning at ages 5 and 18. RESULTS: ADHD groups showed deficits in IQ across development compared to controls; those with persistent ADHD showed the greatest deficit, followed by remitted and late-onset. ADHD groups did not differ from controls in developmental trajectory of IQ, suggesting changes in ADHD were not reflected in IQ. All ADHD groups performed more poorly on executive functioning tasks at ages 5 and 18; persisters and remitters differed only on an inhibitory control task at age 18. CONCLUSIONS: Differences in ADHD course - persistence, remission and late-onset - were not directly reflected in changes in IQ. Instead, having ADHD at any point across development was associated with lower average IQ and poorer executive functioning. Our finding that individuals with persistent ADHD have poorer response inhibition than those who remitted requires replication.

Epigenome-wide Association Study of Attention-Deficit/Hyperactivity Disorder Symptoms in Adults.

BACKGROUND: Previous studies have reported associations between attention-deficit/hyperactivity disorder symptoms and DNA methylation in children. We report the first epigenome-wide association study meta-analysis of adult attention-deficit/hyperactivity disorder symptoms, based on peripheral blood DNA methylation (Infinium HumanMethylation450K array) in three population-based adult cohorts. METHODS: An epigenome-wide association study was performed in the Netherlands Twin Register (N = 2258, mean age 37 years), Dunedin Multidisciplinary Health and Development Study (N = 800, age 38 years), and Environmental Risk Longitudinal Twin Study (N = 1631, age 18 years), and results were combined through meta-analysis (total sample size N = 4689). Region-based analyses accounting for the correlation between nearby methylation sites were also performed. RESULTS: One epigenome-wide significant differentially methylated position was detected in the Dunedin study, but meta-analysis did not detect differentially methylated positions that were robustly associated across cohorts. In region-based analyses, six significant differentially methylation regions (DMRs) were identified in the Netherlands Twin Register, 19 in the Dunedin study, and none in the Environmental Risk Longitudinal Twin Study. Of these DMRs, 92% were associated with methylation quantitative trait loci, and 68% showed moderate to large blood-brain correlations for DNA methylation levels. DMRs included six nonoverlapping DMRs (three in the Netherlands Twin Register, three in the Dunedin study) in the major histocompatibility complex, which were associated with expression of genes in the major histocompatibility complex, including C4A and C4B, previously implicated in schizophrenia. CONCLUSIONS: Our findings point at new candidate loci involved in immune and neuronal functions that await further replication. Our work also illustrates the need for further research to examine to what extent epigenetic associations with psychiatric traits depend on characteristics such as age, comorbidities, exposures, and genetic background.

Evaluating a scale of excessive mind wandering among males and females with and without attention-deficit/hyperactivity disorder from a population sample.

Recent studies highlight the role of excessive mind wandering in attention-deficit/hyperactivity disorder (ADHD) and its association with impairment. We believe assessing mind wandering could be especially relevant to individuals, including many females, who present with less externalising manifestations of ADHD. Using a new measure based on ADHD patient reports, the Mind Excessively Wandering Scale (MEWS), we previously found adults with ADHD had elevated levels of mind wandering that contributed to impairment independently of core ADHD symptoms. Using data from an online general population survey, the current study assessed the factor-structure, reliability, validity and measurement invariance of the MEWS. We also investigated sex differences in mind wandering, as well as ADHD symptoms, impairment and wellbeing in those with and without ADHD. The MEWS had a unidimensional structure, was invariant across sex, age and ADHD status, and accounted for unique variance in impairment and wellbeing beyond core ADHD symptoms. Among those with ADHD, we found no evidence for sex differences in mind wandering and among those without ADHD males had higher scores. We also found similar levels of hyperactivity/impulsivity, emotional lability, and impairment in males and females with ADHD, but males reported greater inattention and lower wellbeing. Results suggest the MEWS is a reliable and valid instrument measuring the same construct across sex, age and ADHD status, which could aid diagnosis and monitoring of outcomes.

Do different factors influence whether girls versus boys meet ADHD diagnostic criteria? Sex differences among children with high ADHD symptoms.

We investigate if different factors influence whether girls versus boys meet diagnostic criteria for attention-deficit/hyperactivity disorder(ADHD) among children with high ADHD symptoms. Participants were 283 children aged 7-12 from a population-based study. Girls and boys meeting diagnostic criteria for ADHD, based on an objective investigator-based interview, were compared to children who did not meet criteria despite high symptoms on a rating-scale measure of ADHD. We assessed factors that could differentially relate to diagnosis across girls and boys including ADHD symptoms, co-occurring behavioural/emotional problems and impairment, and sex-effects in rater perceptions of ADHD symptoms. While overall similar factors distinguished girls and boys who met diagnostic criteria from high-symptom peers, effect sizes were larger in girls. Emotional problems were particularly salient to distinguishing diagnosed versus high-symptom girls but not boys. Parents rated boys meeting diagnostic criteria as more impaired than high-symptom boys but did not do so for girls, and under-rated diagnosed girls' hyperactive/impulsive symptoms compared to more objective interview assessment, with the opposite observed in boys. Results suggest girls' ADHD may need to be made more prominent by additional behavioural/emotional problems for them to meet full diagnostic criteria and that sex differences in parental perceptions of ADHD behaviours and impairment exist.

Annual Research Review: Does late-onset attention-deficit/hyperactivity disorder exist?

Attention-deficit/hyperactivity disorder (ADHD) is conceptualized as an early onset childhood neurodevelopmental disorder. Prevalence in adults is around two-thirds that in childhood, yet longitudinal outcome studies of children with ADHD found a minority continue to meet full criteria in adulthood. This suggests that not all adult cases meet ADHD criteria as children, a conclusion supported by earlier studies relying on retrospective recall in adolescent and adult samples. More recently prospective follow-up of population and control samples suggest that adolescent and young adult ADHD is not always a continuation of childhood ADHD. Here, we review the literature on age of onset, to explore whether late-onset ADHD exists, and if so, examine the evidence for whether this should be considered the same or a different disorder as childhood onset ADHD. We conclude that current evidence supports the view that a significant proportion of young adults meeting criteria for ADHD would not have met full diagnostic criteria for ADHD as children. However, many in the late-onset group show some ADHD symptoms in childhood, or an externalizing disorder such as oppositional defiant disorder. Furthermore, the current studies suggest that most (but not all) cases of late-onset ADHD develop the disorder between the ages of 12-16 and can therefore be considered adolescent or early adult onset ADHD. There is a relative lack of data spanning young to older adulthood to address the question of adult-onset. Currently, there is insufficient data to clarify the extent to which early and late onset ADHD reflect a different balance of genetic and environmental risks or share the same underlying neural mechanisms. Clinicians should be aware that significantly impairing forms of ADHD can emerge beyond the age of 12 years, although perhaps rarely in the context of a complete absence of precursors. The current evidence on treatment responses is limited.

Young adult mental health and functional outcomes among individuals with remitted, persistent and late-onset ADHD.

BACKGROUND: Attention-deficit hyperactivity disorder (ADHD) is associated with mental health problems and functional impairment across many domains. However, how the longitudinal course of ADHD affects later functioning remains unclear.AimsWe aimed to disentangle how ADHD developmental patterns are associated with young adult functioning. METHOD: The Environmental Risk (E-Risk) Longitudinal Twin Study is a population-based cohort of 2232 twins born in England and Wales in 1994-1995. We assessed ADHD in childhood at ages 5, 7, 10 and 12 years and in young adulthood at age 18 years. We examined three developmental patterns of ADHD from childhood to young adulthood - remitted, persistent and late-onset ADHD - and compared these groups with one another and with non-ADHD controls on functioning at age 18 years. We additionally tested whether group differences were attributable to childhood IQ, childhood conduct disorder or familial factors shared between twins. RESULTS: Compared with individuals without ADHD, those with remitted ADHD showed poorer physical health and socioeconomic outcomes in young adulthood. Individuals with persistent or late-onset ADHD showed poorer functioning across all domains, including mental health, substance misuse, psychosocial, physical health and socioeconomic outcomes. Overall, these associations were not explained by childhood IQ, childhood conduct disorder or shared familial factors. CONCLUSIONS: Long-term associations of childhood ADHD with adverse physical health and socioeconomic outcomes underscore the need for early intervention. Young adult ADHD showed stronger associations with poorer mental health, substance misuse and psychosocial outcomes, emphasising the importance of identifying and treating adults with ADHD.Declaration of interestNone.