Subthreshold Attention-deficit/hyperactivity Disorder Research Articles

Prevalence of comorbidity of autism and ADHD and associated characteristics in school population: EPINED study.

Autism and attention deficit hyperactivity disorder (ADHD) comorbidity in the school population have been understudied. This study estimates its prevalence considering both parents' and teachers' reports and clinical diagnosis. Sociodemographic, clinical, and cognitive data were compared by diagnostic groups: autism, ADHD, autism and ADHD, subthreshold autism spectrum disorder (ASD), subthreshold ADHD, and children without neurodevelopmental conditions. Following a two-phase design, 3727 parents and teachers (1802 preschoolers, 1925 school-age children) participated in the first phase. Subsequently, 781 participants underwent individual assessment for DSM-5 diagnoses. The estimated prevalence of the comorbid diagnosis was 0.51% (0.28%-0.74%), with significant sex differences (0.16% girls, 0.89% boys). The cooccurrence of symptoms of autism and ADHD reported by parents or teachers was 3.2% and 2.6%, respectively. ADHD comorbidity was observed in 32.8% of autistic children and 31.4% of those with subthreshold ASD. ASD comorbidity was observed in 9.8% of children with ADHD and 5.7% of those with subthreshold ADHD. Comorbidity was reported by at least one informant in 95% of children. Only 15.8% of children with autism and ADHD had been previously diagnosed with both conditions. Early detection and accurate comorbidity diagnosis are crucial to address the clinical and socio-educational needs of these children.

Cluster analysis of teachers report for identifying symptoms of autism spectrum and/or attention deficit hyperactivity in school population: EPINED study.

An early detection of Neurodevelopmental Disorders (NDDs) is crucial for their prognosis; however, the clinical heterogeneity of some disorders, such as autism spectrum disorder (ASD) or attention-deficit hyperactivity disorder (ADHD) is an obstacle to accurate diagnoses in children. In order to facilitate the screening process, the current study aimed to identify symptom-based clusters among a community-based sample of preschool and school-aged children, using behavioral characteristics reported by teachers. A total of 6894 children were assessed on four key variables: social communication differences, restricted behavior patterns, restless-impulsiveness, and emotional lability (pre-schoolers) or inattention and hyperactivity-impulsivity (school-aged). From these behavioral profiles, four clusters were identified for each age group. A cluster of ASD + ADHD and others including children with no pathology was clearly identified, whereas two other clusters were characterized by subthreshold ASD and/or ADHD symptoms. In the school-age children, the presence of ADHD was consistently observed with ASD patterns. In pre-schoolers, teachers were more proficient at identifying children who received a diagnosis for either ASD and/or ADHD from an early stage. Considering the significance of early detection and intervention of NDDs, teachers' insights are important. Therefore, promptly identifying subthreshold symptoms in children can help to minimize consequences in social and academic functioning.

Predictors of health-related quality of life for children with neurodevelopmental conditions

Neurodevelopmental conditions can be associated with decreased health-related quality of life; however, the predictors of these outcomes remain largely unknown. We characterized the predictors of health-related quality of life (HRQoL) in a sample of neurodiverse children and youth. We used a cross-sectional subsample from the Province of Ontario Neurodevelopmental Disorders Network (POND) consisting of those children and young people in the POND dataset with complete study data (total n = 615; 31% female; age: 11.28 years ± 2.84 years). Using a structural equation model, we investigated the effects of demographics (age, sex, socioeconomic status), core features (Social Communication Questionnaire, Toronto Obsessive Compulsive Scale, Strengths and Weaknesses of attention deficit/hyperactivity disorder (ADHD)-symptoms and Normal Behavior), co-occurring symptoms (Child Behaviour Checklist), and adaptive functioning (Adaptive Behaviour Assessment System) on HRQoL (KINDL). A total of 615 participants had complete data for this study (autism = 135, ADHD = 273, subthreshold ADHD = 7, obsessive–compulsive disorder (OCD) = 38, sub-threshold OCD = 1, neurotypical = 161). Of these participants, 190 (31%) identified as female, and 425 (69%) identified as male. The mean age was 11.28 years ± 2.84 years. Health-related quality of life was negatively associated with co-occurring symptoms (B = − 0.6, SE = 0.20, CI (− 0.95, − 0.19), p = 0.004)) and age (B = − 0.1, SE = 0.04, CI (− 0.19, − 0.01), p = 0.037). Fewer co-occurring symptoms were associated with higher socioeconomic status (B = − 0.5, SE = − 0.05, CI (− 0.58, − 0.37), p < 0.001). This study used a cross-sectional design. Given that one’s experiences, needs, supports, and environment and thus HrQoL may change significantly over the lifespan and a longitudinal analysis of predictors is needed to capture these changes. Future studies with more diverse participant groups are needed. These results demonstrate the importance of behavioural and sociodemographic characteristics on health-related quality of life across neurodevelopmental conditions.

The Clinical Manifestation, Executive Dysfunction, and Caregiver Strain in Subthreshold Attention-Deficit/Hyperactivity Disorder.

Subthreshold attention-deficit/hyperactivity disorder (ADHD) has been suggested to be a "morbid condition" which also needs medical attention. The present study recruited 89 children with subthreshold ADHD (sADHD), 115 children with diagnosed ADHD (cADHD), and 79 healthy controls (HC) to explore the clinical manifestation, executive functions (EFs) of sADHD, and the caregiver strain. The clinical manifestation was evaluated through clinical interviews and parent-reports. Executive functions were assessed both experimentally and ecologically. Caregiver strain was measured by a parent-reported questionnaire. For the clinical manifestation, both sADHD and cADHD indicated impairments when compared with HC. The comorbidities and the scaled symptoms indicated that the externalizing behaviors were relatively less serious in sADHD than cADHD, whereas the internalizing behaviors between two groups were comparable. For ecological EFs, sADHD scored between cADHD and HC in inhibition and working memory. For experimental EFs, sADHD was comparable to cADHD in inhibition, shifting, and was worse than cADHD in verbal working memory. For the caregiver strain, all scores of sADHD were between that in cADHD and that in HC. Our present findings supported the suggestion of subthreshold ADHD as "morbid condition," which should be treated with caution in clinical practice, especially for the internalizing behaviors and some key components of EFs.

Cognitive behavioural group therapy as addition to psychoeducation and pharmacological treatment for adolescents with ADHD symptoms and related impairments: a randomised controlled trial

BackgroundCognitive behavioural therapy (CBT) is recommended for attention-deficit/hyperactivity-disorder (ADHD) in adolescents. However, all CBTs are not created equal, and the guidelines do not specify which CBT interventions are the most effective for this patient group. This study examines the efficacy of a group CBT without parent involvement as follow-up treatment compared to no additional CBT in adolescents with persistent and impairing ADHD symptoms after a short psychoeducational intervention and medical treatment.MethodsThe authors conducted a two-arm parallel randomized controlled trial in two child and adolescent mental health outpatient clinics in Norway. One hundred patients aged 14–18 years with a diagnosis of ADHD (66%) or subthreshold ADHD (34%) were randomized to either a 12-week group CBT program (N = 50) or a non-CBT control condition (N = 50). Assessments were made at admission to the clinic, two weeks before and two weeks after treatment. The primary outcomes were parent-, teacher- and self-ratings of ADHD symptoms (ADHD Rating Scale-IV), and the secondary outcomes were ratings of ADHD symptom severity, executive function, functional impairment, and emotional problems. Evaluators blinded to group allocation rated ADHD symptom severity with the Clinical Global Impression Scale for Severity (CGI-S) at baseline and post-treatment.ResultsAnalyses using mixed-effects models showed no difference between the treatment arms from baseline to post treatment in primary and secondary outcomes.ConclusionsContrary to our hypothesis, we found no incremental treatment effect on the part of a group CBT as follow-up to psychoeducation and pharmacological treatment on ADHD symptoms and accompanying impairments. Limitations with the CBT was the large number and low dosage of treatment components, causing restricted time for practice. Unlike evidence-based, individualized targeted CBTs with parent involvement, a group CBT directed solely at the adolescents with no parent involvement does not appear effective for treating ADHD.Trial registrationNCT02937142, 18/10/2016.

Cognitive Control Deficits in Children With Subthreshold Attention-Deficit/Hyperactivity Disorder.

Subthreshold Attention-Deficit/Hyperactivity Disorder (ADHD) is defined as a neurobiological condition with some core inattentive or hyperactive/impulsive symptoms of ADHD which do not meet the full diagnosis clinically. Although it has been well documented that deficits in cognitive control, a high-level cognitive construct closely related to attention, are frequently found among children with ADHD, whether subthreshold ADHD is also associated with similar deficits remains unclear. In this study, we examined the attention functions and the cognitive control capacity (CCC) in children with ADHD (n = 39), those with subthreshold ADHD (n = 34), and typically developing peers (TD, n = 36). The results showed that the ADHD and subthreshold ADHD groups exhibited similar patterns of the impaired executive function of attention (revealed as an augment in flanker conflict effect) and reduced cognitive control capacity, and no significant difference was found between the two groups. These findings suggest that although children with subthreshold ADHD have not met the full criteria of ADHD, they showed reduced efficiency in cognitive control and attention function, similar to children with ADHD.

Two meta-analyses of the association between atopic diseases and core symptoms of attention deficit hyperactivity disorder

Studies in the field of neuroscience and psychology have hypothesized that a causal association exists between atopic diseases and attention-deficit/hyperactivity disorder (ADHD). Previous systematic reviews and meta-analyses have reported a higher risk of ADHD in children with atopic diseases; however, the relationship between ADHD symptoms and atopic diseases remains unclear. We systematically reviewed observational cross-sectional and longitudinal studies to investigate the relationship between atopic diseases and ADHD symptom severity (hyperactivity/impulsivity and inattention). The majority of studies showed a statistically significant association between atopic diseases and both ADHD symptoms, with substantial heterogeneity in the outcome of hyperactivity/impulsivity. Remarkably decreased heterogeneity and statistical significance were observed in the second meta-analysis of ADHD-related behavior symptoms in atopic patients without ADHD. Our study indicated that atopic diseases not only associated with ADHD but also ADHD symptoms severity. This association was even observed in children with subthreshold ADHD, indicating that atopic diseases may play a role in the spectrum of ADHD symptom severity. Trial registration: This study was registered on PROSPERO (registration ID: CRD42020213219).

Effectiveness of Specific Techniques in Behavioral Teacher Training for Childhood ADHD Behaviors: Secondary Analyses of a Randomized Controlled Microtrial

Behavioral teacher training is an effective intervention for children with attention-deficit/hyperactivity disorder (ADHD). Intervention effectiveness may be enhanced by including intervention components that carry the strongest evidence for their effectiveness. A previous article of this group showed that both antecedent- (i.e., stimulus-control) and consequent-based (i.e., contingency management) techniques were highly effective in reducing daily teacher-rated, individually selected problem behaviors in a specific situation of the child. Effects were observed up to three months post intervention. Here, we tested whether effects were also present in teacher-rated and masked DSM-based assessments that comprise the full range of ADHD and oppositional defiant disorder (ODD) symptoms, as well as on teacher-rated impairment. Teachers of 90 children with (subthreshold) ADHD (6–12 years) were randomly assigned to one of three conditions: a short (two sessions), individualized intervention consisting of either a) antecedent-based techniques or b) consequent-based techniques; or c) waitlist. Multilevel analyses showed that both sets of techniques were effective in reducing teacher-rated ADHD symptoms and impairment immediately after the intervention and up to three months later, as compared to waitlist. Masked observations of ADHD behavior were in line with teacher ratings, with effects being most pronounced for inattention. No effects on teacher-rated or masked ODD behavior were found. This study showed that antecedent- and consequent-based techniques were effective in improving classroom ADHD symptoms and impairment. Long-term changes in teacher-rated ADHD are promising. These results extend previous findings and show the potential of short individually tailored interventions in classroom settings as treatment of ADHD symptoms.

Inhibitory Control in Children with Tourette Syndrome Is Impaired in Everyday Life but Intact during a Stop Signal Task.

Tourette Syndrome (TS) has previously been associated with deficits in inhibitory control (IC). However, studies on IC in individuals with TS have produced conflicting results. In the present study, we investigated IC, comparing the Stop Signal Reaction Time (SSRT) measure with parent and teacher ratings of daily life IC in 169 children aged 8–12 (60 with TS, 60 typically developing controls, 27 with attention-deficit/hyperactivity disorder (ADHD), and 22 with TS + ADHD). We further investigated associations of IC with TS and ADHD symptom severity. Children with TS showed intact SSRT performance, but impairments in daily life IC, as reported by parents and teachers. For the latter, we observed a staircase distribution of groups, with the healthy controls presenting with the best IC, followed by TS, TS + ADHD, and finally ADHD. Dimensional analyses indicated a strong association between ADHD severity and both measures of IC. Our results indicate that children with TS are not impaired in a laboratory-based measure of IC, although some difficulties were evident from measures of everyday behaviour, which may in part be due to parents and teachers interpreting tics as disinhibited behaviour. Comorbid ADHD or the severity of subthreshold ADHD symptomatology appeared to account for IC deficits.

Facial emotion recognition impairment predicts social and emotional problems in children with (subthreshold) ADHD

Children with attention-deficit/hyperactivity disorder (ADHD) symptoms often experience social and emotional problems. Impaired facial emotion recognition has been suggested as a possible underlying mechanism, although impairments may depend on the type and intensity of emotions. We investigated facial emotion recognition in children with (subthreshold) ADHD and controls using a novel task with children’s faces of emotional expressions varying in type and intensity. We further investigated associations between emotion recognition accuracy and social and emotional problems in the ADHD group. 83 children displaying ADHD symptoms and 30 controls (6–12 years) completed the Morphed Facial Emotion Recognition Task (MFERT). The MFERT assesses emotion recognition accuracy on four emotions using five expression intensity levels. Teachers and parents rated social and emotional problems on the Strengths and Difficulties Questionnaire. Repeated measures analysis of variance revealed that the ADHD group showed poorer emotion recognition accuracy compared to controls across emotions (small effect). The significant group by expression intensity interaction (small effect) showed that the increase in accuracy with increasing expression intensity was smaller in the ADHD group compared to controls. Multiple regression analyses within the ADHD group showed that emotion recognition accuracy was inversely related to social and emotional problems, but not prosocial behavior. Not only children with an ADHD diagnosis, but also children with subthreshold ADHD experience impairments in facial emotion recognition. This impairment is predictive for social and emotional problems, which may suggest that emotion recognition may contribute to the development of social and emotional problems in these children.

Examining the Educational Gap for Children with ADHD and Subthreshold ADHD

Objective: The present study examined the impact of Attention Deficit Hyperactivity Disorder (ADHD) on core educational outcomes in two large community cohorts of Australian school children. Method: Academic (reading and numeracy) and non-academic (school engagement, attendance, peer victimization, and parental expectations) outcomes were compared between children with ADHD, subthreshold ADHD, and controls when children were in grade 5 (M age = 10.5). Data were drawn from the Longitudinal Study of Australian Children birth cohort (LSAC; N = 3,540) and the Children’s Attention Project (CAP; N = 356). Results: Both subthreshold ADHD and ADHD groups had poorer outcomes on all measures, with medium effects sizes. Differences were not evident between subthreshold ADHD and ADHD groups. Conclusions: Educational outcomes examined in this study highlight the educational risk for upperprimary school children with ADHD or subthreshold ADHD, in comparison to their peers. Monitoring these outcomes is necessary to inform policy, practice, and intervention.

Should children with sub-threshold ADHD predominantly inattentive subtype (ADHD-I) symptoms be treated with Sensory ıntegration therapy? A case-control study.

Objective: Sensory integration therapy is one of the promising preventive therapy options for behavioral and developmental disorders. Hypothesizing a degree of parallelism, this study provides an insight into the effectiveness of the sensory integration therapy potencies for school-aged children with subthreshold ADHD predominantly inattentive subtype. Method: The study was a single-arm clinical trial and 20 patients aged 7–10 years with subthreshold ADHD predominantly inattentive subtype, were included. The sensory integration intervention was prepared in accordance with sensory modulation principles and intervention strategies and lasted 12 weeks with two sessions per week. The effectiveness was assessed using the Conner’s teacher/parent scales, the Clinical Global Impression scale, the Canadian Sensory integration Performance Measure and the Sensory Profile. Results: The rate of patients with typical or better performance in auditory processing domain of the Sensory Profile was found significantly increased after sensory integration therapy; 9 patients (45%) before and 15 patients after (75%) (p=0.031). The rates of participants with typical or better performance in inattention–distractibility factor score of the Sensory Profile were found significantly increased after sensory integration therapy; 6 before (30%) and 16 after (80%) (p=0.006). Conclusion: Sensory integration therapy focuses on supporting persons with varied disability terms to engage in daily life activities that they find significant and purposeful. Difficulties experienced by individuals with subthreshold attention-deficit hyperactivity disorder are addressed in this study and aspects of daily life are explored while swiping through different sensory modalities. Impaired auditory processing improvable through sensory integration therapy was observed in these children.

Financial decision-making in a community sample of adults with and without current symptoms of ADHD.

Research found that adults with attention deficit hyperactivity disorder (ADHD) have more problems with financial decision-making than healthy controls. The present study investigates the impact of symptoms of ADHD on impulsive buying and the use of financial decision styles. Furthermore, the influence of personality, symptoms of depression and demographics on the association between ADHD and these aspects of financial decision-making is evaluated. A community sample of 1292 participants (age range 18–93 years, 45.4% male) completed questionnaires related to ADHD, impulsive buying, financial decision styles, personal financial situation, depression and personality. Four groups were formed based on self-reported ADHD symptoms: an ‘ADHD’ group (n = 45), an ‘Adult-only ADHD’ group (n = 57), a ‘Subthreshold ADHD’ group (n = 162) and a ‘No ADHD’ group (n = 265). Groups were compared using ANOVA and chi-square tests. Furthermore, multiple regression analyses in the complete sample were employed to examine the association between ADHD and financial decision-making. The ADHD and Adult-only ADHD groups reported significantly more impulsive buying, used more often an avoidant or spontaneous decision style and less often saved money compared to the No ADHD group. Regression analyses revealed that impulsive buying and financial decision styles were not significantly associated with ADHD symptoms when controlling for personality, symptoms of depression and demographics. The present study confirms previous research on adults with ADHD by indicating more impulsive buying and a more frequent use of disadvantageous financial decision styles (i.e., avoidant and spontaneous styles) in individuals with an elevated number of current symptoms of ADHD compared to individuals without symptoms of ADHD. Personality and demographic variables were found to be related to both impulsive buying and the use of specific financial decision styles and might be of influence on the association between impulsive buying, the use of financial decision styles and ADHD.

Cognitive and electrophysiological markers of adult full syndrome and subthreshold attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) has been often referred to as an executive function deficit disorder with a specific electrophysiological signature. Although previous research suggests that individuals with subthreshold symptoms also suffer from severe impairments in daily life, only few studies have investigated cognitive and neural alterations in this group. Here, we explored impairments in executive functions and their electrophysiological correlates in a sample of adults with full syndrome (N = 113) and subthreshold (N = 46) ADHD compared to controls (N = 42). Results suggest that adults with full syndrome ADHD exhibit more executive function deficits than controls, while there were no electrophysiological differences found between groups. Also, we observed only small differences in neuropsychological variables between subthreshold ADHD and controls and no evidence for altered neural activity in the resting state. While subthreshold ADHD was not associated with altered executive functions or abnormal electrophysiological activity, this group reported significant psychological impairments and comorbidity.

Structural brain alterations and their association with cognitive function and symptoms in Attention-deficit/Hyperactivity Disorder families.

Gray matter disruptions have been found consistently in Attention-deficit/Hyperactivity Disorder (ADHD). The organization of these alterations into brain structural networks remains largely unexplored. We investigated 508 participants (281 males) with ADHD (N=210), their unaffected siblings (N=108), individuals with subthreshold ADHD (N=49), and unrelated healthy controls (N=141) with an age range from 7 to 18years old from 336 families in the Dutch NeuroIMAGE project. Source based morphometry was used to examine structural brain network alterations and their association with symptoms and cognitive performance. Two networks showed significant reductions in individuals with ADHD compared to unrelated healthy controls after False Discovery Rate correction. Component A, mainly located in bilateral Crus I, showed a ADHD/typically developing difference with subthreshold cases being intermediate between ADHD and typically developing controls. The unaffected siblings were similar to controls. After correcting for IQ and medication status, component A showed a negative correlation with inattention symptoms across the entire sample. Component B included a maximum cluster in the bilateral insula, where unaffected siblings, similar to individuals with ADHD, showed significantly reduced loadings compared to controls; but no relationship with individual symptoms or cognitive measures was found for component B. This multivariate approach suggests that areas reflecting genetic liability within ADHD are partly separate from those areas modulating symptom severity.

The Contribution of Sensory Sensitivity to Emotional Lability in Children with ADHD Symptoms

ABSTRACTEmotional lability and sensory sensitivity have been shown to contribute to the overall clinical picture in children with attention deficit hyperactivity disorder (ADHD). Further, both of these characteristics have been individually demonstrated to contribute to poorer quality of life, increased functional impairment, and poorer treatment response. However, to date, no study has evaluated the relationship among all three of these factors. The current study hypothesized that increased sensory sensitivity would moderate the relationship between hyperactive/impulsive symptoms of ADHD and emotional lability in youth. Results indicate that heightened sensory sensitivity strengthens the relationship between hyperactive/impulsive symptoms of ADHD and emotional lability in children with three or more clinically impairing ADHD symptoms. This dimensional approach was taken in accordance with growing evidence that even children with sub-threshold ADHD experience significant functional impairment and high rates of sensory sensitivity. These findings suggest that clinicians treating children with ADHD symptoms and emotional lability should consider assessing for sensory sensitivity as integration of multi-sensory techniques or referral to concurrent occupational therapy may significantly improve treatment outcomes and quality of life for these children and their families.

The Effect of Occupational Therapy on Subthreshold Attention Deficit Hyperactivity Disorder

The Effect of Occupational Therapy on Subthreshold Attention Deficit Hyperactivity Disorder

A 9-Year Follow-Up of Attention-Deficit/Hyperactivity Disorder in a Population Sample.

Prior follow-up studies of attention-deficit/hyperactivity disorder (ADHD) have mostly been from North America. They have provided a good deal of information about ADHD, but whether these results generalize to population samples and to other countries is not certain. Most prior studies have also not assessed predictors of possible new onsets of ADHD in non-ADHD youth or the validity of subthreshold forms of the disorder. 1,012 families were recruited at baseline, when a telephone interview assessed a child in the 6-12 years age range. The interview covered symptoms of ADHD, conduct disorder, and oppositional defiant disorder as well as family living situation, school performance, sleep disturbance, eating habits, use of supplemental iron, and history of ADHD treatment. Nine years later, the persistence of ADHD and its impairments and the emergence of new conditions were assessed. DSM-5 diagnostic criteria were used to diagnose ADHD. 492 of the 1,012 participants seen at baseline were followed up 9 years later, at a mean age of 18 years. At follow-up, 16.7% of the children diagnosed with ADHD at baseline met full criteria for ADHD and 11.1% met criteria for subthreshold ADHD, yielding a persistence rate of 27.8%. Among children not diagnosed with ADHD at baseline, 1.1% met criteria for ADHD at follow-up. The persistence of ADHD and new onsets of ADHD were predicted by several baseline clinical features and by a family history of ADHD. We replicated predictors of the persistence of ADHD found in prior studies and provide new data about predictors of new ADHD onsets in the population. Our findings about subthreshold ADHD support a dimensional conceptualization of the disorder, highlighting the potential clinical utility of a subthreshold diagnostic category. This study also contributes to the ongoing debate regarding adult-onset ADHD.

Are subsyndromal manifestations of attention deficit hyperactivity disorder morbid in children? A systematic qualitative review of the literature with meta-analysis

We conducted a qualitative review (n = 15 manuscripts) and meta-analysis (n = 9 manuscripts) of the extant literature to evaluate the prevalence and morbidity of subthreshold Attention Deficit Hyperactivity Disorder (ADHD). Our qualitative review showed that a sizable minority (mean: 17.7%) of clinically referred and non-referred children met a priori definitions of subthreshold ADHD. Those affected exhibited significantly higher rates of family dysfunction, cognitive impairment, executive dysfunction, interpersonal and school deficits, temperament problems, psychiatric comorbidity, and juvenile delinquency compared to children with no ADHD symptoms. These deficits were highly consistent with those observed in children with full threshold ADHD. These findings indicate that children with subthreshold ADHD symptoms are at significantly greater risk for negative outcomes in a wide range of non-overlapping functional domains worthy of further clinical and scientific consideration.

Further Evidence of Morbidity and Dysfunction Associated With Subsyndromal ADHD in Clinically Referred Children.

While the diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) have evolved over the years, some children with impairing ADHD symptoms fail to meet the full diagnostic threshold for the disorder. The main aim of this study was to evaluate the morbidity and dysfunction of subsyndromal ADHD in the clinical setting. Subthreshold and full ADHD subjects were derived from consecutive referrals (n = 2,947) to a pediatric psychopharmacology program at a major academic center. Subjects were diagnosed with subthreshold ADHD if they met at least 1 of the following criteria: (1) their age at onset for ADHD was ≥ 7 years; (2) they had ≥ 5 but < 8 ADHD symptoms using the DSM-III-R or ≥ 4 but < 6 ADHD inattentive or hyperactive/impulsive symptoms using the DSM-IV. Healthy controls were derived from 2 identically designed longitudinal case-control studies of youth with and without ADHD. Psychiatric assessments relied on clinical structured interviews and measures of psychopathology, social functioning, cognitive ability, and academic achievement. Of the 1,931 children diagnosed with ADHD, 140 (7%) were diagnosed with subthreshold ADHD. 48% of subthreshold ADHD subjects had an age at onset ≥ 7 years, and 73% had insufficient symptoms. Reanalysis of findings using DSM-5 criteria showed that only 21% of our subthreshold ADHD subjects would have met DSM-5 criteria based on age at onset of < 12 years, while 79% would have maintained their subthreshold diagnoses. Subjects with subthreshold ADHD differed from controls in the mean number of comorbid disorders; rates of mood, anxiety, and elimination disorders (all P < .001) and substance use disorders (P < .05); scores on all Child Behavior Checklist clinical and social functioning scales; scores on 7 of the 10 Social Adjustment Inventory for Children and Adolescents scales; rates of requiring extra help in school and being placed in a special class; and scores on 4 of the 5 Wechsler Intelligence Scale for Children-Revised Version subscales (excluding Digit Span) as well as in Freedom from Distractibility Index score (P < .001). Subthreshold and full ADHD subjects had similarly elevated Global Assessment of Functioning scores versus controls (P < .001), but subjects with subthreshold ADHD had fewer perinatal complications and better family functioning scores and were more likely to be female and older and to come from families of higher socioeconomic status than subjects with full ADHD. Clinically referred children failing to meet full-threshold diagnosis for ADHD due to either insufficient symptoms or later age at onset have patterns of clinical features highly similar to those with the full syndrome. These results extend to previously reported findings in nonreferred samples documenting the high morbidity and disability associated with subthreshold ADHD.