Symptoms of Attention Deficit Hyperactivity Disorder in Children and Adults with Intellectual Disability: A Review

Neurocognitive Characteristics of Patients Who Visited a Psychiatric Outpatient Clinic Requesting Treatment for Adult Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

This study investigated the neurocognitive characteristics of patients who visited an outpatient clinic requesting diagnosis and treatment for adult attention-deficit/hyperactivity disorder (ADHD).

METHODS

The patients' electronic medical records were retrospectively reviewed. Neurocognitive test results were compared using Student's t-test according to their chief complaint, depressive symptoms, childhood history, and intelligence quotient (IQ). Neurocognitive characteristics affecting subjective symptoms of ADHD were analyzed by linear regression.

RESULTS

The study included 106 patients. They did not have significant deficits in neurocognitive tests. Patients with depressive symptoms showed more impulsive responses (hit reaction time [p=0.037] and commission error [p=0.024]) and self-reported ADHD symptoms (p=0.001). Verbal (p=0.036) and visual memory (p=0.020) were significantly deficient in patients with a childhood ADHD diagnosis. Patients with a low IQ had significant deficits in various domains. Depressive symptoms and vigilance were significantly related to subjective symptoms of ADHD (adjusted R2=0.430, β=0.457, p=0.002).

CONCLUSION

Our results imply that the neurocognitive function of patients with subjective ADHD symptoms was not abnormal but was affected by depressive symptoms.

Diagnosis and pharmacological management of attention deficit hyperactivity disorder in adults with and without intellectual disability: cohort study using electronic health records

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is increasingly diagnosed in adults. People with intellectual disability have higher rates of ADHD yet there is little evidence on the presentation and pharmacological treatment of ADHD in this population or how this differs from the general population.

METHODS

Retrospective cohort study using data from electronic health records. Adults with intellectual disability newly diagnosed with ADHD between 2007 and 2022 were matched to adults with ADHD without intellectual disability and their clinical features and treatments were compared.

RESULTS

A total of 159 adults with ADHD and intellectual disability and 648 adults with ADHD without intellectual disability formed the dataset. Adults with intellectual disability had higher rates of psychiatric co-morbidity and spent more time under mental health services than those without intellectual disability. They were more likely to have recorded agitation, aggression, hostility, and mood instability, and less likely to have poor concentration recorded in the 12 months prior to the diagnosis of ADHD. Following diagnosis, people with intellectual disability were significantly less likely to be prescribed any medication for ADHD than controls without intellectual disability (adjusted odds ratio 0.60, 95% confidence interval 0.38-0.91), and were less likely to be prescribed stimulants (27.7% v 46.0%, p < 0.001).

CONCLUSIONS

The presence of behaviors that challenge in adults with intellectual disability may indicate co-occurring ADHD. Further work to define the safety and efficacy of medication for ADHD in adults with intellectual disability is needed to understand differences in prescription rates and to avoid inequities in care outcomes.

Assessing and managing attention-deficit hyperactivity disorder in people with intellectual disability

Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with a higher prevalence rate in people with intellectual disability compared with their peers without such disability. The classic presentation is that of inattention and/or hyperactivity and impulsivity, but these symptoms can manifest differently in people with intellectual disability. Despite a higher prevalence, the rate of diagnosis and treatment of ADHD in intellectual disability remains low. This article discusses the clinical presentation of ADHD in people with intellectual disability and the relationship between ADHD and other comorbid conditions, such as autism and bipolar disorder. Pharmacological and non-pharmacological interventions are discussed from a practical and a clinical point of view.

Validity of the SNAP-IV For ADHD Assessment in South African Children With Neurodevelopmental Disorders

This study investigated the psychometric properties of the Swanson, Nolan, and Pelham ADHD Rating Scale (SNAP-IV) in a sample of South African children with neurodevelopmental disorders (n = 201), primarily Autism Spectrum Disorder and Intellectual Disability. We conducted a confirmatory factor analysis to inspect the two-factor structure of the SNAP-IV. We also calculated ordinal coefficient alpha to estimate internal consistency. Fit statistics for the two-factor model approached acceptable levels. The model fit improved slightly after removing an item related to spoken language. The subscales had acceptable internal consistencies. Findings partially support the use of the SNAP-IV in this group of children. However, there are limitations to its performance in this population likely related to the presence of neurodevelopmental disorders.

Actigraph-Measured Movement Correlates of Attention-Deficit/Hyperactivity Disorder (ADHD) Symptoms in Young People with Tuberous Sclerosis Complex (TSC) with and without Intellectual Disability and Autism Spectrum Disorder (ASD)

Actigraphy, an objective measure of motor activity, reliably indexes increased movement levels in attention-deficit/hyperactivity disorder (ADHD) and may be useful for diagnosis and treatment-monitoring. However, actigraphy has not been examined in complex neurodevelopmental conditions. This study used actigraphy to objectively measure movement levels in individuals with a complex neurodevelopmental genetic disorder, tuberous sclerosis (TSC). Thirty participants with TSC (11–21 years, 20 females, IQ = 35–108) underwent brief (approximately 1 h) daytime actigraph assessment during two settings: movie viewing and cognitive testing. Multiple linear regressions were used to test associations between movement measurements and parent-rated ADHD symptoms. Correlations were used to examine associations between actigraph measures and parent-rated ADHD symptoms and other characteristics of TSC (symptoms of autism spectrum disorder (ASD), intellectual ability (IQ), epilepsy severity, cortical tuber count). Higher movement levels during movies were associated with higher parent-rated ADHD symptoms. Higher ADHD symptoms and actigraph-measured movement levels during movies were positively associated with ASD symptoms and negatively associated with IQ. Inter-individual variability of movement during movies was not associated with parent-rated hyperactivity or IQ but was negatively associated with ASD symptoms. There were no associations with tuber count or epilepsy. Our findings suggest that actigraph-measured movement provides a useful correlate of ADHD in TSC.

Diagnosis of Attention Deficit Hyperactivity Disorder in Intellectual Disability: Diagnostic and Statistical Manual of Mental Disorder V versus clinical impression

BACKGROUND

Diagnosing Attention Deficit Hyperactivity Disorder (ADHD) in people with intellectual disability (ID) remains challenging. The Diagnostic and Statistical Manual of Mental Disorder V (DSM V) classification system is often used to diagnose ADHD in the general population; however, the presence of ID and other associated conditions such as autism and communication difficulties can make it difficult to apply the DSM V criteria in people with ID. Therefore, diagnosing ADHD in people with ID is often made using clinical judgement and/or the application of diagnostic criteria. There are no studies comparing the diagnostic accuracy of clinical judgement and the use of DSM V criteria in people with ID and ADHD.

METHOD

The aims of the study were to compare the accuracy of the diagnosis of ADHD in people with ID according to the DSM V criteria versus clinical judgement and to determine which criteria are more reliable. A questionnaire was developed using five fictional case scenarios of people with ID. Questionnaires were presented to practising psychiatrists chosen as a convenience sample in the United Kingdom over a period of 12 months. Case scenarios were developed and agreed to be positive or negative for ADHD by the study authors prior to rating by clinicians. The clinicians were asked to read the scenarios and to make a judgement on the cases regarding the symptoms of ADHD. They were then presented with the 18 DSM V criteria of ADHD and asked to select the criteria they considered were present in each scenario. Sensitivity, specificity, likelihood ratios and predictive values for both the DSM V criteria and clinical opinions were calculated for correctly identifying the exemplar cases.

RESULTS

The data showed strong sensitivity [0.82 95% confidence interval (CI) 0.74-0.89] and high specificity (1.00 95% CI 0.95-1.00) for the raters' clinical opinion. In contrast, the DSM V criteria alone, as assessed by the raters, did not reliably provide ADHD diagnoses, with a sensitivity of only 0.23 (95% CI 0.15-0.31). This difference in sensitivity between the two was statistically significant at P < 0.001.

CONCLUSION

The study results suggest that clinical opinion is the 'gold standard' at present in diagnosing ADHD in adults with ID in the absence of a validated diagnostic tool in this group. Further studies are needed to understand how symptoms of ADHD can be presented differently in people with ID. DSM V criteria for ADHD may need to be adapted according to the severity of ID and other neurodevelopmental disorders.

Hyperkinetic disorder in a community service for people with intellectual disability

BACKGROUND

There appears to be a higher rate of prevalence of hyperkinetic disorder in the intellectual disability (ID) population, although there is a large variability in rates in previous studies. Hyperkinetic disorder can be a challenge to diagnose in a population with ID and can present a barrier to the development of the activities of daily living in an already vulnerable population.

OBJECTIVES

Our objective was to examine the point prevalence of hyperkinetic disorder in the ID population in a community ID service and also to determine the prevalence of hyperkinetic disorder based on the level of ID.

METHODS

A cross-sectional review of the Online Information Service 'OLIS' database was undertaken to establish the total number of patients with ID and those with comorbid hyperkinetic disorder. The overall point prevalence and prevalence based on the level of ID was calculated from the collected data.

RESULTS

The point prevalence of hyperkinetic disorder in the population with ID was similar to that found in studies in the general population at 3.1% in adults and 32.6% in children. When divided by the level of disability, the calculated point prevalence in both adults and children was highest in the population with mild ID and decreased as the level of disability increased.

CONCLUSION

This report contributes to previous research establishing the rates of hyperkinetic disorder in an ID population and establishes the point prevalence of hyperkinetic disorder in individuals diagnosed with ID in a clinical sample.

Dual Diagnosis: A Problematic Construct When Applied to Persons with Intellectual Disabilities

The term dual diagnosis can refer to the co-occurrence of an intellectual disability and a mental disorder. While such a term may have some advocacy rationale aimed at facilitating improved mental health care for those with intellectual disabilities, it is proposed that the construct has flawed underpinnings, and its application may problematize mental health service delivery. A core concern is the promotion of categorical diagnostic models, whereas dimensional models may more accurately reflect underlying continuums for both cognitive and mental health challenges. A categorical diagnostic approach may also contribute to questionable dichotomization of mental health difficulties in persons with intellectual disabilities into "problem or challenging behaviours" versus "mental disorders." Organizing services based on beliefs that such distinctions and categorical classifications are accurate may contribute to unnecessary and inappropriate fractionation of interventions and create additional service barriers for a vulnerable population. It is proposed that the term dual diagnosis be abandoned and replaced by systematic use of a dimensional approach to help facilitate assessment, intervention evaluation, and equitable service access.

Invariance of parent ratings of attention deficit hyperactivity disorder symptoms for children with and without intellectual disability

BACKGROUND

Although attention deficit hyperactivity disorder (ADHD) is considered a valid diagnosis for children with intellectual disability, no studies have evaluated the invariance of ADHD symptom ratings across children with and without intellectual disability.

METHOD

Parents completed ratings on the ADHD symptoms for 189 children with intellectual disability and for 474 children without intellectual disability. Differential item functioning analysis was used to determine the equivalence of the ADHD symptoms across the two groups.

RESULTS

The symptoms loses things, talks too much, and blurts out answers showed significant bias against children with intellectual disability. The prevalence of ADHD in children with intellectual disability was 18% (according to the symptom criterion), and 7.4% when the academic and/or social impairment criterion was also considered.

CONCLUSIONS

Most of the ADHD symptoms can be valid for the assessment of ADHD in children with mild and moderate intellectual disability. ADHD symptoms may be used in further studies to establish base rates of the disorder in the intellectual disability population.

Parent- and Teacher-Reported Symptoms of ADHD in School-Aged Children With Active Epilepsy: A Population-Based Study

OBJECTIVE

Provide data on the distribution of parent- and teacher-reported symptoms of ADHD in childhood epilepsy and describe coexisting cognitive and behavioral disorders in children with both epilepsy and ADHD.

METHOD

Eighty-five (74% of those eligible) children (5-15 years) in a population-based sample with active epilepsy underwent psychological assessment. The ADHD Rating Scale-IV (ADHD-RS-IV) scale was completed by parents ( n = 69) and teachers ( n = 67) of participating children with an IQ > 34. ADHD was diagnosed with respect to Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.).

RESULTS

Parents reported significantly more symptoms of ADHD than teachers ( p < .001). Symptoms of inattention were more commonly reported than symptoms of hyperactivity-impulsivity ( p < .001). Neurobehavioral comorbidity was similar in those with ADHD and non-ADHD with the exception of oppositional defiant disorder (ODD) and developmental coordination disorder (DCD), which were more common in those with both epilepsy and ADHD.

CONCLUSION

Symptoms of ADHD are very common in childhood epilepsy but prevalence is influenced by informant.

ASD, ADHD, mental health conditions and psychopharmacology in neurogenetic syndromes: parent survey

BACKGROUND

There are a number of neurogenetic syndromes with well described behavioural phenotypes including fragile X syndrome, Prader-Willi syndrome, Williams syndrome and velo-cardio-facial syndrome (VCFS). Autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and psychiatric conditions are often associated with the syndromes.

METHOD

Parents (n = 381) of school-aged children with one of the four syndromes in the UK and Ireland were asked whether their child had been professionally diagnosed with ASD, ADHD or a mental health condition. Parents were also asked whether their child had been prescribed medication for behavioural or psychiatric reasons.

RESULTS

The highest level of reported diagnoses of ASD and ADHD was in fragile X syndrome. In all syndrome groups, lower rates of diagnosis were reported in comparison to previously published research. Prescribing of medication for behavioural/psychiatric reasons was highest in fragile X syndrome although the highest usage of melatonin was in Williams syndrome.

CONCLUSION

Reasons for a lower recognition of ASD, ADHD and mental health conditions in clinical practice compared with research studies may include 'diagnostic overshadowing' due to presence of intellectual disability and a genetic syndrome. However, there may also be a lack of belief in the utility of such diagnoses in neurogenetic syndromes among relevant professionals and/or lack of access to professionals with sufficient expertise in the recognition of such diagnoses in those with neurogenetic syndromes. The low rates of prescribing of medication for behavioural/psychiatric reasons may reflect the low level of clinical diagnoses or lack of belief in the utility of psychopharmacology in this population.

The subjective well-being of individuals diagnosed with comorbid intellectual disability and attention deficit hyperactivity disorders

PURPOSE

The present study's aim was to empirically explore subjective well-being (SWB) and its correlates among adults diagnosed with comorbid intellectual disability (ID) and attention deficit hyperactivity disorder (ADHD). This exploration was guided by the Theory of SWB Homeostasis as a conceptual framework for examining determinants and processes underlying the SWB of this understudied population.

METHOD

A total of 246 adults receiving residential support completed questionnaires measuring their SWB, ADHD symptomatology, functional limitations, and individual internal (self-determination) and external (financial resources, and social support) resources.

RESULTS

The participants' SWB was found to be within the normative range. ADHD symptomatology directly predicted reductions in SWB; however, according to the theory, this effect was fully mediated by the individual's internal and external resources.

CONCLUSIONS

The main findings support the applicability of the SWB Homeostasis theory for understanding the SWB of individuals with comorbid ID and ADHD. The study findings shed light on the psychosocial determinants of SWB and highlight the importance of psychosocial resources as buffers of the effect of health and environmental conditions.

ADHD among adolescents with intellectual disabilities: pre-pathway influences

Children and adolescents with intellectual disabilities (ID) are at heightened risk for developing ADHD. However, the validity of ADHD as a diagnosis for youth with ID remains controversial. To advance research on validity, the present study examined the hypothesized precursors to ADHD in typically developing adolescents (TD) and adolescents with ID, specifically with regard to family history of ADHD, molecular genetics, and neuropsychological functioning. Results indicated that youth ADHD symptoms were related to parental ADHD symptoms regardless of the adolescent's cognitive functioning. Additionally, findings suggested that the DRD4 genetic variant and adolescent set-shifting abilities were related to adolescent ADHD symptoms independent of cognitive functioning. This study provides an initial investigation of the biological correlates of ADHD among youth with ID.