Geographical variation in ADHD: do diagnoses reflect symptom levels?

Individual child factors affecting the diagnosis of attention deficit hyperactivity disorder (ADHD) in children and adolescents: a systematic review

Attention deficit hyperactivity disorder (ADHD) is a prevalent condition characterised by patterns of inattention, hyperactivity, and impulsivity. This systematic literature review aims to identify the child clinical and sociodemographic factors related to the detection and diagnosis of ADHD in children and adolescents, given concerns about delays or failures in identifying ADHD as well as over-diagnosis, hindering appropriate and timely support for children and families. Through electronic and manual searches of peer-reviewed and grey literature, 5852 articles were identified and subjected to two stages of screening by independent reviewers. Due to the heterogeneity in study methods, a narrative approach was used to summarise study findings. Forty-one studies meeting eligibility criteria revealed sixteen child-related factors influencing the ADHD diagnostic process. These factors include ADHD subtype, ADHD symptom severity, comorbid mental disorders, behavior problems, internalizing symptoms, functional impairment, social and cognitive functioning, physical health, gender, age, relative age, race/ethnicity, socio-economic status, insurance coverage, residence urbanicity, and family structure. While the impact of many of these factors on ADHD diagnosis was inconsistent due to the substantial diversity in study designs and context, certain patterns emerged. Meeting the criteria for the inattentive subtype, lower functional impairment, female gender, Black or Latinx ethnicity, and being relatively young for their grade were consistently found to be associated with a delayed or absent ADHD diagnosis. Further research is needed to explore the intricate relationships between these child-level variables and their implications for ADHD recognition, referral, and evaluation, especially outside the USA.

Catchment area characteristics do not account for geographical variation in ADHD diagnoses

BACKGROUND

Geographical variation in Attention-Deficit/Hyperactivity Disorder (ADHD) diagnoses remains poorly understood. Previous research has found that the variation in ADHD rates between Child and Adolescent Mental Health Services (CAMHS) is not attributable to ADHD symptom load in the catchment areas of the CAMHS. This study aimed to investigate if geographical variation in rates of ADHD-diagnosis per population and per patient, as well as referral rates to CAMHS, were associated with catchment area characteristics.

METHODS

We used data from the Norwegian Patient Registry, covering everyone aged 5-18 in contact with CAMHS 2009-2011, and catchment area level data from Statistics Norway, including population size, centrality, socioeconomic position, welfare reliance, and general population health. Spearman's Rho was calculated to assess the strength and direction of monotonic correlation.

RESULTS

Referral rates to CAMHS per population were lower in catchment areas with higher proportion of non-European population; more urban areas; fewer adults receiving disability benefits; and more economic inequality. Higher rates of ADHD per population were seen in areas characterised by lower socio-economic position. The rate of ADHD diagnosis per patient in CAMHS ranged from 5 to 27% and was not associated with catchment area characteristics.

CONCLUSION

This study found that the proportion of ADHD diagnoses per population was moderately related to catchment area characteristics, following a social gradient in health. However, the proportion of ADHD diagnoses among patients in CAMHS was unrelated to area characteristics. This suggests that other factors, such as variation in clinician attitudes or local practice styles, may contribute to the strong variation in ADHD diagnoses.

Neurodevelopmental Tics with Co-Morbid Functional Tic-like Behaviors: Diagnostic Challenges of a Complex Tourette Syndrome Phenotype

Background/Objectives: The co-morbidity between neurodevelopmental tics and functional tic-like behaviors (FTBs) in patients with Tourette syndrome (TS) is relatively under-investigated. The demographic and clinical characteristics of a large sample of patients with TS who presented with co-morbid FTBs (functional overlay) were assessed to raise awareness of this complex clinical presentation and to shed light on the differential diagnosis between the two conditions. Methods: We analyzed the clinical data of 63 patients (44 females, mean age 24 years, range 13-40) with pre-existing TS who (sub)acutely developed co-morbid FTBs (TS + FTBs) after the onset of the COVID-19 pandemic and compared them with 63 age- and gender-matched controls with TS (neurodevelopmental tics only). The diagnosis of co-morbid FTBs was validated by the European Society for the Study of Tourette Syndrome (ESSTS) criteria. Results: Complex vocal tics (p < 0.001), including coprolalia (p = 0.002), and self-injurious behaviors (p < 0.001), often as part of tic attacks (p < 0.001), were confirmed to be more commonly reported by the group of patients with TS + FTBs, who were also more likely to present with anxiety (p < 0.001) and other functional neurological symptoms (p < 0.001) compared to patients with TS. Conclusions: Patients with TS and co-morbid FTBs can pose significant diagnostic and treatment challenges. By systematically applying ESSTS criteria, we confirmed specific red flags for the diagnosis of functional overlay in patients with TS. The correct identification of this composite clinical phenotype plays a key role in preventing the misdiagnosis of treatment-resistant TS and implementing tailored treatment interventions.

Negotiating Normalcy: Epistemic Errors in Self-Diagnosing Late-ADHD

In this paper, I share insights from ongoing ethnographic fieldwork among adult Danes who identify as having Attention Deficit Hyperactivity Disorder (ADHD) but do not meet the clinical standards and have yet to receive a diagnosis. These individuals are particularly relevant to the ongoing debates about under- and overdiagnosis of ADHD, as their claims to the diagnosis influence and mirror societal perceptions of what is considered normal and what is seen as a condition. Despite their symptoms not strictly meeting diagnostic criteria, thus risking overdiagnosis and associated psychiatric labeling, they perceive themselves as distinct from 'normal' people. Through a critical anthropological lens, I argue that medicalizing variations in human personality represents a contemporary societal epistemic error, drawing on Gregory Bateson's work. I highlight the dynamics of diagnosis versus notions of normality in diagnosing and self-diagnosing ADHD. Understanding these dynamics is crucial for addressing concerns of overdiagnosis as well as underdiagnosis and misdiagnosis. By illuminating the complexities of diagnostic processes and their societal implications, I aim to contribute to a richer understanding of mental health discourse and practice.

Incidence of Attention-Deficit/Hyperactivity Disorder Between 2016 and 2023: A Retrospective Cohort

Objective

The present retrospective cohort study sought to advance our understanding of the incidence and recent trends in new ADHD diagnoses among adolescents and adults between 2016 and 2023 in a clinical setting.

Method

Participants (N = 144,103) included adolescents and adult patients who actively utilized Sisters of Saint Mary (SSM) healthcare services. ICD-10 codes were used to identify new ADHD diagnoses in patient charts. Joinpoint regression analysis determined incidence rates and trends of ADHD diagnoses, stratified by age group.

Results

In adults, a significant (-10.6%; 95% CI -25.0%, -2.8%) downward trend in ADHD incidence was observed from 2016 to 2020, whereas a significant (+15.2%; 95% CI: 2.0%, 40.3%) upward trend was indicated from 2020 to 2023. Among adolescents, a significant (-26.1%; 95% CI: -33.4%, -14.4%) downward trend was observed between 2016 and 2018, while the incidence rate remained stable during 2018-2023.

Conclusions

This study is one of the largest retrospective cohort studies to investigate the incidence of new ADHD diagnoses among adolescents and adults in clinical practice, including before, during, and after the height of the COVID-19 pandemic. Results indicate fluctuations in the incidence rates of new ADHD diagnoses in recent years, with well-defined trends observed for adolescents and adults. Future directions should include the investigation of the underlying factors contributing to these diagnostic trends.

Relevance to clinical practice

Advancing our understanding of diagnostic trends in clinical practice promotes accurate diagnosis and improved management of ADHD. Study findings support future investigation in identifying potential modifiable risk factors, ensuring sufficient treatment resources, developing targeted interventions, and addressing diagnostic disparities.

Effect of pharmacological treatment of attention-deficit/hyperactivity disorder on later psychiatric comorbidity: a population-based prospective long-term study

BACKGROUND

Psychiatric comorbidity is frequent among persons with attention-deficit/hyperactivity disorder (ADHD). Whether pharmacological treatment of ADHD influences the incidence of psychiatric comorbidity is uncertain.

OBJECTIVE

To investigate associations and causal relations between pharmacological treatment of ADHD and incidence of subsequent comorbid psychiatric diagnoses.

METHODS

We employed registry data covering all individuals aged 5-18 years in Norway who were diagnosed with ADHD during 2009-2011 (n=8051), followed until 2020. We used linear probability models (LPM) and instrumental variable (IV) analyses to examine associations and causal effects, respectively, between pharmacological treatment and subsequent comorbidity.

FINDINGS

From time of ADHD diagnosis to 9 years of follow-up, 63% of patients were registered with comorbid psychiatric disorders. For males, LPM showed associations between ADHD medication and several incident comorbidities, but strength and direction of associations and consistency over time varied. For females, no associations were statistically significant. IV analyses for selected categories isolating effects among patients 'on the margin of treatment' showed a protective effect for a category of stress-related disorders in females and for tic disorders in males for the first 2 and 3 years of pharmacological treatment, respectively.

CONCLUSIONS

Overall, LPM and IV analyses did not provide consistent or credible support for long-term effects of pharmacological treatment on later psychiatric comorbidity. However, IV results suggest that for patients on the margin of treatment, pharmacological treatment may initially reduce the incidence of certain categories of comorbid disorders.

CLINICAL IMPLICATIONS

Clinicians working with persons with ADHD should monitor the effects of ADHD medication on later psychiatric comorbidity.

TRIAL REGISTRATION NUMBER

ISRCTN11891971.

Effect of ADHD medication on risk of injuries: a preference-based instrumental variable analysis

ADHD is associated with an increased risk of injury. Causal evidence for effects of pharmacological treatment on injuries is scarce. We estimated effects of ADHD medication on injuries using variation in provider preference as an instrumental variable (IV). Using Norwegian registry data, we followed 8051 patients who were diagnosed with ADHD aged 5 to 18 between 2009 and 2011 and recorded their ADHD medication and injuries treated in emergency rooms and emergency wards up to 4 years after diagnosis. Persons with ADHD had an increased risk of injuries compared to the general population (RR 1.35; 95% CI: 1.30-1.39), with higher risk in females (RR 1.47; 95% CI: 1.38-1.56) than males (RR 1.23; 95% CI: 1.18-1.28). The between-clinics variation in provider preference for ADHD medication was large and had a considerable impact on patients' treatment status. There was no causal evidence for protective effects of pharmacological treatment on injuries overall for young individuals with ADHD characterized by milder or atypical symptoms. However, there was an apparent effect of pharmacological treatment over time on the risk of injuries treated at emergency wards in this patient group.

Effect of Pharmacological Treatment of Attention-Deficit/Hyperactivity Disorder on Criminality

OBJECTIVE

Criminality rates are higher among persons with attention-deficit/hyperactivity disorder (ADHD), and evidence that medication reduces crime is limited. Medication rates between clinics vary widely even within universal health care systems, partly because of providers' treatment preferences. We used this variation to estimate causal effects of pharmacological treatment of ADHD on 4-year criminal outcomes.

METHOD

We used Norwegian population-level registry data to identify all unique patients aged 10 to 18 years diagnosed with ADHD between 2009 and 2011 (n = 5,624), their use of ADHD medication, and subsequent criminal charges. An instrumental variable design, exploiting variation in provider preference for ADHD medication between clinics, was used to identify causal effects of ADHD medication on crime among patients on the margin of treatment, that is, patients who receive treatment because of their provider's preference.

RESULTS

Criminality was higher in patients with ADHD relative to the general population. Medication preference varied between clinics and strongly affected patients' treatment. Instrumental variable analyses supported a protective effect of pharmacological treatment on violence-related and public-order-related charges with numbers needed to treat of 14 and 8, respectively. There was no evidence for effects on drug-, traffic-, sexual-, or property-related charges.

CONCLUSION

This is the first study to demonstrate causal effects of pharmacological treatment of ADHD on some types of crimes in a population-based natural experiment. Pharmacological treatment of ADHD reduced crime related to impulsive-reactive behavior in patients with ADHD on the margin of treatment. No effects were found on crimes requiring criminal intent, conspiracy, and planning.

STUDY PREREGISTRATION INFORMATION

The ADHD controversy project: Long-term effects of ADHD medication; https://www.isrctn.com/; 11891971.

Perspectives on ADHD in children and adolescents as a social construct amidst rising prevalence of diagnosis and medication use

The diagnosis of attention-deficit hyperactivity disorder (ADHD) is based on the presence of pervasive, persistent symptoms of inattention and/or hyperactivity/impulsivity typically emerging early in life and resulting in significant functional impairment. In contrast to a worldwide epidemiological prevalence of approximately 5% in children and 2-3% in adults, there are significant variations in the prevalence of administrative ADHD diagnoses and medication use. We assert that in order to explore the underlying dynamics of this phenomenon, a thorough understanding of the construct ADHD is necessary. We contend that ADHD is not a natural entity that unfolds within an individual and can be understood independent from societal and environmental factors, but rather that ADHD as a diagnosis can better be conceptualized as a valid and pragmatically useful social construct. Decisions to diagnose and treat ADHD should follow a person-centered approach and be focused on functional impairment within a socially constructed, context-dependent and environmentally contingent model.

Variation in attitudes toward diagnosis and medication of ADHD: a survey among clinicians in the Norwegian child and adolescent mental health services

Prevalence and medication rates of ADHD vary geographically, both between and within countries. No absolute cutoff exists between ADHD and normal behavior, making clinician attitudes (leading to local practice cultures) a potential explanation for the observed variation in diagnosis and medication rates. The objective of this study was to describe variation in attitudes toward diagnosis and medication of ADHD among clinicians working in child and adolescent mental health services (CAMHS). We hypothesized that attitudes would vary along a spectrum from "restrictive" to "liberal". We also explored whether differences in attitudes between clinicians were related to professional background and workplace (clinic). A survey in the form of a web-based questionnaire was developed. All CAMHS outpatient clinics in Norway were invited. Potential respondents were all clinicians involved in diagnosing and treating children and adolescents with ADHD. To investigate the existence of attitudes toward diagnosis and medication as latent constructs, we applied confirmatory factor analysis (CFA). We further examined how much of variance in attitudes could be ascribed to profession and clinics by estimating intraclass correlation coefficients. In total, 674 respondents representing 77 (88%) of the clinics participated. We confirmed variation in attitudes with average responses leaning toward the "restrictive" end of the spectrum. CFA supported "attitude toward diagnosis" and "attitude toward medication" as separate, and moderately correlated (r = 0.4) latent variables, representing a scale from restrictive to liberal. Professional background and workplace explained only a small part of variance in these attitudes.

Differences between centers in functional outcome of patients with ADHD after 1 year from the time of diagnosis

Although the pharmacological therapy of ADHD has been widely studied, little has been done to compare the different therapeutic approaches (e.g., drug therapy vs. psychological treatments) and even less has been done to compare the outcome of the therapy between centers. This multicenter observational study aims to assess between-center variation in functional outcome of ADHD patients one year after the diagnosis, according to the treatment received. We used the Regional ADHD Registry data on 1429 patients enrolled in 16 ADHD centers in the 2011-2022 period. To evaluate the effectiveness of the therapy we used a generalized linear mixed model with the center as the random effect, including patient condition at diagnosis and center characteristics, weighting by the inverse of the propensity score of the treatment received by the patient. Between-center variation was expressed as the relative difference in odds-ratios between the observed and the expected number of patients whose condition improved, using the Clinical Global Impressions-Improvement Scale (CGI-I), and the relative 95% CI. Patients who received combined treatment were significantly more likely to improve compared to other treatment groups (65.5% vs 54.4% for methylphenidate alone, 53.4% for psychological treatment alone, or 40.5% for no therapy). Adjusted for patients and center characteristics, the log-odds ratio ranged from 0.85 (0.29-1.55 95% CI) to - 0.64 (- 1.17-- 0.18 95% CI). The mean expected probability of improvement after one year of therapy for an average patient with ADHD for each center was 47.7% in a center at the 25th percentile and 61.2% in a center at the 75th percentile of the outcome distribution after adjustments. The wide between-center variation in patient functional improvement one year after the diagnosis of ADHD could be largely explained by center-specific therapeutic approaches or attitudes. More careful and stringent work is needed to reduce differences in responses between centers, as could formal and periodic audit programs within and between centers.

Overcoming the phenomenological Perpetuum mobile in clinical cognitive neuroscience for the benefit of replicability in research and the societal view on mental disorders

Cognitive neuroscience comes in many facets, and a particularly large branch of research is conducted in individuals with mental health problems. This article outlines why it is important that cognitive neuroscientists re-shape their role in mental health research and re-define directions of research for the next decades. At present, cognitive neuroscience research in mental health is too firmly rooted in categorial diagnostic definitions of mental health conditions. It is discussed why this hampers a mechanistic understanding of brain functions underlying mental health problems and why this is a problem for replicability in research. A possible solution to these problems is presented. This solution affects the strategy of research questions to be asked, how current trends to increase replicability in research can or cannot be applied in the mental health field and how data are analyzed. Of note, these aspects are not only relevant for the scientific process, but affect the societal view on mental disorders and the position of affected individuals as members of society, as well as the debate on the inclusion of so-called WEIRD and non-WEIRD people in studies. Accordingly, societal and science political aspects of re-defining the role of cognitive neuroscientists in mental health research are elaborated that will be important to shape cognitive neuroscience in mental health for the next decades.