Adult-Onset ADHD: A Critical Analysis and Alternative Explanations

Unraveling ADHD: genes, co-occurring traits, and developmental dynamics

Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental condition with a high prevalence of co-occurring conditions, contributing to increased difficulty in long-term management. Genome-wide association studies have identified variants shared between ADHD and co-occurring psychiatric disorders; however, the genetic mechanisms are not fully understood. We integrated gene expression and spatial organization data into a two-sample Mendelian randomization study for putatively causal ADHD genes in fetal and adult cortical tissues. We identified four genes putatively causal for ADHD in cortical tissues (fetal: ST3GAL3, PTPRF, PIDD1; adult: ST3GAL3, TIE1). Protein-protein interaction databases seeded with the causal ADHD genes identified biological pathways linking these genes with conditions (e.g., rheumatoid arthritis) and biomarkers (e.g., lymphocyte counts) known to be associated with ADHD, but without previously shown genetic relationships. The analysis was repeated on adult liver tissue, where putatively causal ADHD gene ST3GAL3 was linked to cholesterol traits. This analysis provides insight into the tissue-dependent temporal relationships between ADHD, co-occurring traits, and biomarkers. Importantly, it delivers evidence for the genetic interplay between co-occurring conditions, both previously studied and unstudied, with ADHD.

Women with Symptoms Suggestive of ADHD Are More Likely to Report Symptoms of Iron Deficiency and Heavy Menstrual Bleeding

BACKGROUND/OBJECTIVES

Iron deficiency has been suggested as a potential mechanism for attention-deficit hyperactivity disorder (ADHD) development due to involvement in neurotransmitter synthesis and transporter expression. As iron deficiency is particularly common in women of reproductive age, often due to heavy menstrual bleeding (HMB), we aimed to explore the relationship between iron deficiency, HMB and ADHD in women.

METHODS

We screened women (18-49 years) at university and local sporting events in Western Australia. To screen for ADHD, section A of the Adult ADHD Self-Report Scale-V1.1 (ASRS-V1.1) and the Adult Concentration Inventory were used to assess cognitive disengagement syndrome (CDS) symptoms. Risk factors for iron deficiency, such as HMB, commonly reported symptoms and a fingerpick haemoglobin concentration (Hb) (Hemocue Hb801) were recorded.

RESULTS

Of the 405 completed questionnaires, the mean age was 24.8 ± 10.1 years, the mean Hb was 136.8 ± 12.4 g/L and 6.4% of women were anaemic. Symptoms suggestive of ADHD were reported by 174/405 (43%) women, and 128/405 (32%) women reported HMB. There was a greater prevalence of HMB reported in those experiencing symptoms suggestive of ADHD (39% vs. 26%, p = 0.01). Symptoms of fatigue, dizziness, brain fog, anxiety, heart palpitations, headaches, restless legs and depression were more common in patients with symptoms suggestive of ADHD (p ? 0.01) and HMB (p < 0.05). Anaemia status did not influence ADHD status (p = 0.87) nor CDS scores (15.7 ± 7.0 vs. 13.8 ± 6.1, p = 0.17).

CONCLUSIONS

There is an apparent relationship between those with symptoms reported in ADHD, HMB and iron deficiency. Further exploration is required to determine whether there is a causative relationship.

Investigating the Mediating Role of Executive Function in the Relationship Between ADHD and DCD Symptoms and Depression in Adults

This study was designed to test the effects of Attention Deficit Hyperactivity Disorder (ADHD) and Developmental Co-ordination Disorder (DCD) on depression levels and investigate the mediating role of executive function (EF) in adults. Adults with ADHD, DCD, and ADHD + DCD (N = 139) completed self-report measures of ADHD, DCD, depression, and EF. There were distinct profiles of EF across diagnostic groups, and higher depression symptoms in adults with ADHD + DCD than DCD alone. All EF domains were predicted by ADHD symptoms, and several by DCD symptoms. ADHD and DCD symptoms, and most EF domains, predicted depression symptoms. Overall EF difficulties fully mediated the relationships between ADHD/DCD and depression symptoms. Several specific EF domains relating to behavioural regulation and metacognition also showed full/partial mediating effects. The mediating role of EF difficulties between these neurodevelopmental conditions and depression symptoms has implications for their understanding and treatment, suggesting that targeting EF may be important for preventing co-occurring depression.

Cyclothymic affective temperament and low positive attitude coping strategies as predictors of comorbid depressive symptomatology in adult ADHD patients

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) in adults could be frequently underdiagnosed due to concomitant psychiatric disorders, including depressive symptomatology, which could determine inappropriate treatments. Our study aims at clinically characterizing adult ADHD with or without depressive symptomatology in order to identify the relationship with specific affective temperamental profiles and coping strategies.

METHODS

A total of 225 outpatients consecutively afferent to our outpatient adult ADHD service since September 2019 were retrospectively screened for eligibility and administered Beck Depression Inventory-II (BDI-II), Coping Orientation to Problems Experienced Inventory (COPE-NV) and Temperament Evaluation of the Memphis, Pisa, Paris and San Diego (TEMPS-M).

RESULTS

64.7 % of patients displayed a significant comorbid depressive symptomatology. According to the multivariate linear regression model, depressive levels were positively predicted by TEMPS-M cyclothymic subscale (B = 0.567, p = 0.004) and negatively predicted by COPE-NVI "positive attitude" subscale (B = -0.438, p = 0.024) (R = 0.496, R2 = 0.246, F(2,66) = 10.747, p < 0.001).

LIMITATION

While considering the results, it should be taken in consideration that: the assessment was carried out only at baseline, our sample is constituted only by adult ADHD patients and mostly without a previous ADHD diagnosis, the presence of a discrepancy between the rates of ADHD subtypes, the absence of a healthy control group and emotional dysregulation was not directly assessed.

CONCLUSION

Affective temperamental profiles and coping strategies could help in clinically characterizing and personalizing treatment in adult comorbid ADHD-depressive symptomatology patients. Further research is warranted to explore the efficacy of targeted psychotherapeutic and pharmacological interventions within this ADHD sub-sample.

Subclinical attention-deficit hyperactivity disorder symptoms and unhealthy lifestyle behaviours

BACKGROUND

Literature emphasises the importance of identifying and intervening in the adoption of unhealthy lifestyle behaviours (ULBs) during adolescence at an early stage, to mitigate their long-term detrimental effects. Among the possible associated factors contributing to ULBs, attention-deficit hyperactivity disorder (ADHD) has been shown to play an important role. However, little is known about ADHD subclinical manifestations.

AIMS

The present study aimed to bridge the gap in the literature and shed light on the relationship between subclinical ADHD and early adoption of ULBs during adolescence. Through a clinimetric approach, prevalence of ULBs, severity of ADHD symptoms and psychosocial factors (i.e. allostatic overload, abnormal illness behaviour, quality of life, psychological well-being) were investigated among adolescents. The associations between different degrees of ADHD, ULBs and psychosocial factors were also explored.

METHOD

This multicentre cross-sectional study involved 440 adolescents (54.5% females; mean age 14.21 years) from six upper secondary schools. Participants completed self-report questionnaires on sociodemographic characteristics, ULBs, ADHD symptoms and psychosocial factors.

RESULTS

The most common ULBs were energy drinks/alcohol consumption and problematic smartphone use. Of the sample, 22% showed subclinical ADHD and 20.2% showed clinical ADHD. The subclinical ADHD group showed several ULBs (i.e. altered mindful eating, impaired quality of sleep, problematic technology use) and psychosocial factors, akin to those of ADHD group and different from peers without ADHD symptoms.

CONCLUSIONS

Since subclinical ADHD manifestation is associated with ULBs, similarly to clinical ADHD, identifying subthreshold symptoms during adolescence is crucial, as it could improve health-related outcomes in adulthood across different domains.

ADHD: prevalence and effect on opioid use disorder treatment outcome in a French sample of patients receiving medication for opioid use disorder-the influence of impulsivity as a mediating factor

BACKGROUND

Opioid use disorder (OUD) poses a global health challenge, and despite medications for opioid use disorder (MOUD) and psychosocial interventions, relapse remains a significant concern. Comorbid psychiatric disorders, including attention deficit hyperactivity disorder (ADHD), are one of the major factors associated with poor OUD treatment outcome. We aimed to estimate the frequency of probable ADHD (in childhood and in adulthood) in patients with OUD; to assess the factors associated with this comorbidity; and to explore the factors that mediate the relationship between ADHD and OUD treatment outcome.

METHODS

We conducted an observational study using a sample of 229 patients aged 18 years and older who were diagnosed with OUD and had received MOUD for at least six months. Participants were assessed through a structured interview and self-report questionnaires. Multivariate logistic regressions and a mediation analysis were performed.

RESULTS

Almost half of the participants reported probable ADHD in childhood, and ADHD persisted into adulthood among two-thirds of the patients. The factors associated with poor OUD treatment outcome included earlier onset of OUD, lower education, and greater impulsivity. There was no direct effect of probable ADHD in childhood on OUD treatment outcome, but there was an indirect effect through negative urgency, the tendency to respond impulsively to negatively connoted emotional experiences.

CONCLUSIONS

The findings suggest that ADHD symptoms, particularly impulsivity, may contribute to vulnerability in opioid use and play a crucial role in treatment outcomes for this population.

TRIAL REGISTRATION

ClinicalTrials identifier NCT01847729.

Attention-Deficit/Hyperactivity Disorder Diagnoses in Finland During the COVID-19 Pandemic

Importance

Several reports suggest an increase in attention-deficit/hyperactivity disorder (ADHD) symptoms during the COVID-19 pandemic. This nationwide study assessed new ADHD diagnoses and ADHD prevalence before and during the pandemic.

Objective

To investigate trends in new ADHD diagnoses, prevalence, and ADHD medication use from 2015 to 2022 in Finland.

Design, Setting, and Participants

This longitudinal cohort study comprised the entire Finnish population. ADHD diagnoses and medication use were obtained from nationwide registers and assessed at 3 time points: in 2015 and before (2020) and after (2022) the pandemic. Data were analyzed from January 2015 to June 2022.

Main outcomes and Measures

New ADHD diagnoses, ADHD lifetime prevalence, and ADHD medication use.

Results

The cohort comprised 5 572 420 individuals (2 819 645 women [50.6%]). Lifetime prevalence of ADHD increased by 2.7-fold during 2015 to 2022; prevalence was 1.02% in 2015 (95% CI, 1.01%-1.03%), 1.80% in 2020 (95% CI, 1.79%-1.81%), and 2.76% in 2022 (95% CI, 2.75%-2.77%). Young men aged 13 to 20 years had the highest lifetime prevalence of 11.68% (95% CI, 11.56%-11.81%) in 2022. New ADHD diagnoses doubled during the pandemic, from 238 per 100 000 in 2020 to 477 per 100 000 in 2022. The pandemic-associated incremental increase in new diagnoses was 18.60% (95% CI, 16.47%-20.49%; 9482 per 50 897 cases). Young women aged 13 to 20 years had a 2.6-fold increase in new diagnoses during the pandemic, from 577 per 100 000 in 2020 to 1488 per 100 000 in 2022, and women aged 21 to 30 years had a 3.0-fold increase, from 361 per 100 000 to 1100 per 100 000. New diagnoses increased by 2.9-fold among those older than 55 years (from 5 per 100 000 to 13 per 100 000 in women and from 5 per 100 000 to 14 per 100 000 in men). Boys younger than 13 years had the highest absolute rate of new ADHD diagnoses in 2022 (1745 per 100 000), but boys and young men younger than 21 years did not show a significant incremental increase in new diagnoses. Lifetime prevalence of ADHD medication purchases was 0.57% (95% CI, 0.56%-0.58%) in 2015 (31 771 [55.62%] of those with ADHD diagnosis), 1.15% (95% CI, 1.14%-1.16%) in 2020 (64 034 [63.83%]), and 1.69% (95% CI 1.68%-1.70%) in 2022 (92 557 [61.43%]), respectively.

Conclusions and Relevance

In this nationwide cohort study, new ADHD diagnoses and ADHD prevalence showed significant increase in Finland during the pandemic. ADHD medication use did not increase in relation to ADHD diagnoses. These results highlight potential adverse outcomes of pandemic-associated changes in living conditions.

Attention-deficit/hyperactivity disorder combined subtype exacerbates opioid use disorder consequences: Mediation by impulsive phenotypes

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is highly prevalent and associated with opioid use disorder (OUD). Yet, little is known about the mechanisms by which ADHD (which is a heterogeneous construct/diagnosis) might alter the trajectory of OUD outcomes in persons who use heroin.

AIM

We examined whether ADHD subtypes are related to heroin-use consequences and the extent to which the effects of ADHD on lifetime heroin-use consequences are mediated by two impulsivity factors that may be partly independent of ADHD: foreshortened time perspective and drug-use impulsivity.

METHODS

Individuals who reported regular heroin use (N=250) were screened using the Assessment of Hyperactivity and Attention (AHA), Impulsive Relapse Questionnaire (IRQ), Stanford Time Perception Inventory (STPI), and a comprehensive assessment of lifetime and current substance use and substance-related consequences. This secondary analysis examined whether ADHD or intermediate phenotypes predicted heroin-use consequences.

RESULTS

Relative to participants whose AHA scores indicated lifetime absence of ADHD (n=88), those with scores indicating persistent ADHD (childhood and adult, n=62) endorsed significantly more total lifetime heroin-use consequences despite comparable heroin-use severity. Likewise, there was a significant indirect effect of the combined ADHD subtype in childhood on lifetime heroin-use consequences. This effect was mediated by STPI scores indicating less future (and more hedonism in the present) temporal orientation and by IRQ scores indicating less capacity for delaying drug use.

CONCLUSION

The combined ADHD subtype is significantly associated with lifetime heroin-use consequences, and this effect is mediated through higher drug-use impulsivity (less capacity for delay) and lower future temporal orientation.

Differentiating Performance on the Connors Continuous Performance Test (CPT-3) as a Function of Comorbid Internalizing Psychopathology

OBJECTIVE

Internalizing psychopathology commonly co-occurs with attention-deficit/hyperactivity disorder (ADHD). Attention concerns are present in both ADHD and internalizing disorders, yet the neuropsychological functioning of those with comorbid ADHD and internalizing psychopathology is underexamined.

METHOD

This study compared Conners' Continuous Performance Test-Third Edition (CPT-3) profiles across ADHD (n = 141), internalizing psychopathology (n = 78), and comorbid (ADHD/internalizing psychopathology; n = 240) groups.

RESULTS

Compared to the internalizing psychopathology group, the comorbid group had higher mean T-scores on CPT-3 indices indicative of inattentiveness and impulsivity and more clinically elevated T-scores (T>60) on indices measuring inattentiveness and impaired sustained attention. Patients in the comorbid group were also more likely to have abnormal overall CPT-3 profiles (>2 elevated T-scores) than the ADHD and psychopathology only groups.

CONCLUSION

Patients with comorbid ADHD/internalizing psychopathology may evidence a more impaired attentional performance on the CPT-3, which could aid in more tailored treatment planning.

Genetic contribution to the comorbidity between attention-deficit/hyperactivity disorder and substance use disorders

We characterized the genetic architecture of the attention-deficit hyperactivity disorder-substance use disorder (ADHD-SUD) relationship by investigating genetic correlation, causality, pleiotropy, and common polygenic risk. Summary statistics from genome-wide association studies (GWAS) were used to investigate ADHD (Neff = 51,568), cannabis use disorder (CanUD, Neff = 161,053), opioid use disorder (OUD, Neff = 57,120), problematic alcohol use (PAU, Neff = 502,272), and problematic tobacco use (PTU, Neff = 97,836). ADHD, CanUD, and OUD GWAS meta-analyses included cohorts with case definitions based on different diagnostic criteria. PAU GWAS combined information related to alcohol use disorder, alcohol dependence, and the items related to alcohol problematic consequences assessed by the alcohol use disorders identification test. PTU GWAS was generated a multi-trait analysis including information regarding Fagerström Test for Nicotine Dependence and cigarettes per day. Linkage disequilibrium score regression analyses indicated positive genetic correlation with CanUD, OUD, PAU, and PTU. Genomic structural equation modeling showed that these genetic correlations were related to two latent factors: one including ADHD, CanUD, and PTU and the other with OUD and PAU. The evidence of a causal effect of PAU and PTU on ADHD was stronger than the reverse in the two-sample Mendelian randomization analysis. Conversely, similar strength of evidence was found between ADHD and CanUD. CADM2 rs62250713 was a pleiotropic SNP between ADHD and all SUDs. We found seven, one, and twenty-eight pleiotropic variants between ADHD and CanUD, PAU, and PTU, respectively. Finally, OUD, CanUD, and PAU PRS were associated with increased odds of ADHD. Our findings demonstrated the contribution of multiple pleiotropic mechanisms to the comorbidity between ADHD and SUDs.

ADHD in Adults: Does Age at Diagnosis Matter?

OBJECTIVE

To provide additional information about clinical features associated with adult ADHD in patients diagnosed in childhood compared to those first diagnosed in adulthood.

METHOD

We stratified a sample of adults with ADHD into patients diagnosed in childhood versus adulthood and compared demographic and clinical characteristics.

RESULTS

We found similar clinical features in adults diagnosed in childhood and adults diagnosed in adulthood. Among those diagnosed in adulthood, 95% reported symptom onset in youth. Our results do not support the hypothesis that ADHD diagnosed in adulthood is due to misinterpreting symptoms of other disorders as ADHD. They also suggest incorporating behavioral signs of executive dysfunction into diagnostic criteria for ADHD in adults may increase diagnostic sensitivity.

CONCLUSION

These results support the validity of ADHD diagnoses in adulthood, as these adults show similar clinical profiles to those diagnosed in youth. Our results also suggest that if adult-onset ADHD exists, it is rare.

Attention-Deficit / Hyperactivity Disorder in Athletes

ADHD is common among the general population and may be slightly more common among athletes. Diagnosis requires six or more DSM-5-TR symptoms to have been present prior to age 12 and to have an effect on functioning in multiple settings. Different sporting organizations have varying requirements for documentation when making a diagnosis. Stimulant medications are the mainstay of treatment; psychosocial interventions, exercise, and non-stimulant medications can serve as adjuncts. Future directions in research on ADHD in sports include determining whether ADHD is overrepresented among the population of elite athletes and parsing out the relationship between ADHD and concussion risk and recovery.

Reducing Risk in the Treatment of Attention-Deficit/Hyperactivity Disorder Among Adults With Comorbidities

Recent widely publicized shortages in the U.S. supply of first-line medications for treatment of attention-deficit/hyperactivity disorder (ADHD) are thought to reflect increases in public awareness, help seeking, and treatment. ADHD is one of the most common neurodevelopmental disorders and is typically identified in childhood. In adulthood, ADHD symptoms are less likely to include hyperactivity, but inattention, impulsivity, and emotional dysregulation are common. Clinical evaluation of symptomatic adults who were not diagnosed as children requires corroboration of ADHD diagnostic symptoms in childhood and careful differentiation of ADHD from frequently co-occurring psychiatric and substance use disorders. Treatment of adult ADHD can result in improved functioning across multiple dimensions and comorbid disorders. Existing guidelines and consensus statements recommend an integrated approach to treating ADHD and all existing comorbid disorders, prioritizing the disorder that is creating the most difficulty for the individual. [Journal of Psychosocial Nursing and Mental Health Services, 62(1), 8-11.].

Compared Profile of Late-Onset Versus Childhood-Onset ADHD: A Case-Control Study Among Treatment-Seeking Adult Patients

OBJECTIVE

To compare the characteristics of childhood-onset versus late-onset Attention Deficit Hyperactivity Disorder (ADHD) in a sample of treatment-seeking patients.

METHOD

Among total of 101 adult patients who were recently diagnosed for ADHD, using the Diagnostic Interview for Adult ADHD (DIVA 2.0), 56 subjects exhibited childhood-onset ADHD, versus 45 displayed late-onset ADHD. Both groups were compared according to their sociodemographic, clinical, and neuropsychological features, providing crude (OR) and adjusted odds ratios (aOR), and their 95% confidence intervals [95% CI].

RESULTS

Compared to late-onset ADHD, patients with childhood-onset had a lower educational score, (OR = 0.52; 95% CI [0.35, 0.76]), a greater score of impulsivity (aOR = 1.09; 95% CI [1.03, 1.16]), an increased number of hyperactive-impulsive ADHD symptoms (aOR = 1.9; 95% CI [1.46, 2.47]), and higher rates childhood trauma (aOR = 1.07; 95% CI [1.01, 1.13]), cannabis use disorder (aOR = 1.07; 95% CI [1.01, 1.13]), and working memory impairment. No difference was observed concerning age, sex, psychiatric symptoms, quality of life, and autonomy.

CONCLUSION

Childhood-onset adult ADHD displayed a more severe profile, relative to late-onset ADHD.

Assessing aetiological overlap between child and adult attention-deficit hyperactivity disorder symptoms in an extended family design

BACKGROUND

Several longitudinal studies have cast doubt on the aetiological overlap between child and adult attention-deficit hyperactivity disorder (ADHD). However, a lack of genetically sensitive data following children across adulthood precludes direct evaluation of aetiological overlap between child and adult ADHD.

AIMS

We circumvent the existing gap in longitudinal data by exploring genetic overlap between maternal (adult) and offspring (child) ADHD and comorbid symptoms in an extended family cohort.

METHOD

Data were drawn from the Norwegian Mother, Father and Child Cohort Study, a Norwegian birth registry cohort of 114 500 children and their parents. Medical Birth Registry of Norway data were used to link extended families. Mothers self-reported their own ADHD symptoms when children were aged 3 years; reported children's ADHD symptoms at age 5 years; and children's ADHD, oppositional defiant disorder (ODD), conduct disorder, anxiety and depression symptoms at age 8 years. Genetic correlations were derived from Multiple-Children-of-Twins-and-Siblings and extended bivariate twin models.

RESULTS

Phenotypic correlations between adult ADHD symptoms and child ADHD, ODD, conduct disorder, anxiety and depression symptoms at age 8 years were underpinned by medium-to-large genetic correlations (child ADHD: rG = 0.55, 95% CI 0.43-0.93; ODD: rG = 0.80, 95% CI 0.46-1; conduct disorder: rG = 0.44, 95% CI 0.28-1; anxiety: rG = 0.72, 95% CI 0.48-1; depression: rG = 1, 95% CI 0.66-1). These cross-generational adult-child genetic correlations were of a comparable magnitude to equivalent child-child genetic correlations with ADHD symptoms at age 5 years.

CONCLUSIONS

Our findings provide genetically sensitive evidence that ADHD symptoms in adulthood share a common genetic architecture with symptoms of ADHD and four comorbid disorders at age 8 years. These findings suggest that in the majority of cases, ADHD symptoms in adulthood are not aetiologically distinct from in childhood.

Adult Attention-Deficit/Hyperactivity Disorder: a Narrative Review of Biological Mechanisms, Treatments, and Outcomes

PURPOSE OF REVIEW

Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous and complex neurodevelopmental disorder related to disruptions in various neuronal structures and pathways, dopamine (DA) transporter, and receptor genes, resulting in cognitive and regulation deficits. This article reviews recent research on the biological mechanisms and markers, clinical manifestations, treatments, and outcomes of adult ADHD as well as current controversies within the field.

RECENT FINDINGS

New research identifies white matter disruptions in multiple cortical pathways in adults with ADHD. New treatments for ADHD in adults such as viloxazine ER have shown preliminary effectiveness in addition to research showing transcranial direct current stimulation can be an effective treatment for adults with ADHD. Although questions exist about the effectiveness of current assessments of and treatments for adult ADHD, recent findings represent a step towards improving the quality of life and outcomes for individuals experiencing this life-long, chronic health condition.

Sex and gender in neurodevelopmental conditions

Health-related conditions often differ qualitatively or quantitatively between individuals of different birth-assigned sexes and gender identities, and/or with different gendered experiences, requiring tailored care. Studying the moderating and mediating effects of sex-related and gender-related factors on impairment, disability, wellbeing and health is of paramount importance especially for neurodivergent individuals, who are diagnosed with neurodevelopmental conditions with uneven sex/gender distributions. Researchers have become aware of the myriad influences that sex-related and gender-related variables have on the manifestations of neurodevelopmental conditions, and contemporary work has begun to investigate the mechanisms through which these effects are mediated. Here we describe topical concepts of sex and gender science, summarize current knowledge, and discuss research and clinical challenges related to autism, attention-deficit/hyperactivity disorder and other neurodevelopmental conditions. We consider sex and gender in the context of epidemiology, behavioural phenotypes, neurobiology, genetics, endocrinology and neighbouring disciplines. The available evidence supports the view that sex and gender are important contributors to the biological and behavioural variability in neurodevelopmental conditions. Methodological caveats such as frequent conflation of sex and gender constructs, inappropriate measurement of these constructs and under-representation of specific demographic groups (for example, female and gender minority individuals and people with intellectual disabilities) limit the translational potential of research so far. Future research and clinical implementation should integrate sex and gender into next-generation diagnostics, mechanistic investigations and support practices.

The Burden of Attention-Deficit/Hyperactivity Disorder Traits in Adult Patients with Major Depressive Disorder in Japan

Purpose

Symptoms of attention-deficit/hyperactivity disorder (ADHD) often overlap with and are hidden by those of mood disorders, including major depressive disorder (MDD), resulting in adult ADHD patients being misdiagnosed as MDD. This study aims to examine if diagnosed MDD patients are more likely to exhibit ADHD traits and if the presence of ADHD traits increases the humanistic burden, including the impairment of health-related quality of life (HRQoL), work productivity and activity impairment (WPAI), and health-care resource utilization (HRU), on MDD patients in Japan.

Methods

This study utilized existing National Health and Wellness Survey (NHWS) data. The 2016 Japan NHWS is an internet-based survey comprising a total of 39,000 respondents, including those with MDD and/or ADHD. A randomly selected subset of the respondents responded to the Japanese-version Adult ADHD self-report scale (ASRS-v1.1; ASRS-J) symptom checklist. Respondents were considered ASRS-J-positive if the total score was ≥36. The HRQoL, WPAI, and HRU were assessed.

Results

Among MDD patients (n = 267), 19.9% were screened ASRS-J-positive, while 4.0% of non-MDD respondents (n = 8885) were ASRS-J-positive. There was a significant association between MDD status and ASRS-J status (crude odds-ratio [OR]: 5.9) as well as between MDD status and ADHD-diagnosis status (crude OR: 22.6). MDD patients who were ASRS-J positive experienced significantly lower HRQoL and higher WPAI than those who were ASRS-J negative. Limitations of this study include potential recall bias owing to the self-report nature of the survey and lack of objective confirmation of MDD diagnosis through review of medical records.

Conclusion

This study demonstrated a significant association between MDD status and exhibiting ADHD traits. Adult MDD patients screened ASRS-J-positive experienced significantly higher humanistic burden than patients screened ASRS-J-negative. Our results emphasize the importance of ensuring appropriate screening of ADHD and looking out for potentially hidden ADHD symptoms when diagnosing and treating MDD in adulthood.

ADHD in Adults: A Systematic Review and Meta-Analysis of Prevalence Studies in Outpatient Psychiatric Clinics

OBJECTIVE

Systematic review and meta-analysis to estimate the pooled prevalence of ADHD in adult attendees of outpatient mental health clinics and to investigate factors influencing prevalence rates.

METHODS

The following were extracted: demographics, design of the study (screening only or two-phase), scales/criteria for diagnosis of ADHD, number of ADHD, and non-ADHD participants.

RESULTS

The pooled prevalence of ADHD from screening studies (n = 9) was 26.7%, (95% CI [17.2-37.4]), ADHD = 1727, No ADHD = 3,578. From studies employing a two-stage design (n = 5), prevalence was 14.61%, CI [10.39-19.41], ADHD = 561, No ADHD = 3,578. Age and gender did not have any significant effect on the estimated prevalence. By contrast exclusion of psychotic disorders lowers prevalence. The screening scale used also influence prevalence rates.

CONCLUSION

Meta-analysis shows high rates of adult ADHD among psychiatric outpatient clinics. Applying DSM-5 criteria increased prevalence rates. More methodologically robust studies, using two-stage design, need to be conducted to help assist in service planning.

Toward Precision Medicine in ADHD

Attention-Deficit Hyperactivity Disorder (ADHD) is a complex and heterogeneous neurodevelopmental condition for which curative treatments are lacking. Whilst pharmacological treatments are generally effective and safe, there is considerable inter-individual variability among patients regarding treatment response, required dose, and tolerability. Many of the non-pharmacological treatments, which are preferred to drug-treatment by some patients, either lack efficacy for core symptoms or are associated with small effect sizes. No evidence-based decision tools are currently available to allocate pharmacological or psychosocial treatments based on the patient's clinical, environmental, cognitive, genetic, or biological characteristics. We systematically reviewed potential biomarkers that may help in diagnosing ADHD and/or stratifying ADHD into more homogeneous subgroups and/or predict clinical course, treatment response, and long-term outcome across the lifespan. Most work involved exploratory studies with cognitive, actigraphic and EEG diagnostic markers to predict ADHD, along with relatively few studies exploring markers to subtype ADHD and predict response to treatment. There is a critical need for multisite prospective carefully designed experimentally controlled or observational studies to identify biomarkers that index inter-individual variability and/or predict treatment response.