Delayed recognition of autism spectrum disorder and attention-deficit/hyperactivity disorder in a girl with ornithine transcarbamylase deficiency: A case report.

RATIONALE: Ornithine transcarbamylase (OTC) deficiency, a urea cycle disorder, is a rare congenital metabolic error that leads to hyperammonemia. Psychiatric symptoms of hyperammonemia are nonspecific and can cause autism spectrum disorder (ASD)-like symptoms and attention-deficit/hyperactivity disorder (ADHD)-like symptoms. Some studies report that OTC deficiency is often initially diagnosed as ASD or ADHD. However, there are no reports of OTC deficiency comorbid with ASD and ADHD. PATIENT CONCERNS: The patient is 17-year-old girl diagnosed with OTC deficiency at 3 years of age. She had behavioral problems since childhood, including depressed mood, irritability, and impulsive behavior; however, they were considered OTC-mediated nonspecific psychiatric symptoms. Therefore, the patient had not been appropriately assessed for ASD and ADHD. She presented with depressed mood and self-harm at 17 years of age. DIAGNOSES: We diagnosed her with ASD and ADHD based on her medical history and semistructured interviews. INTERVENTIONS: We focused her ASD and ADHD traits and discussed strategies with her for better adaptive living. OUTCOMES: Our interventions resulted in her better social adjustment. LESSONS: Physicians should consider the possibility of comorbid ASD and ADHD in individuals with OTC, facilitating appropriate and intervention for better outcomes.

Adoption of inpatient family-based treatment for anorexia nervosa: A case report.

Background: Family-based treatment (FBT) is effective for the treatment of anorexia nervosa (AN) in children and adolescents. However, its availability in Japan is limited because it requires adherence to specific guidelines, commitment of sufficient time for frequent outpatient treatment, as well as the entire family's participation. We present a case of a patient with AN who was treated with modified FBT during hospitalization. Case Presentation: Our patient was a 14-year-old girl with AN. She was hospitalized for malnutrition and dehydration, and was introduced to FBT during this period. After discharge, she continued FBT on an outpatient basis and was in remission 1 year later. Conclusion: This case shows that initiation of FBT during hospitalization may be useful in patients with physically severe AN. Flexible adaptation to each of the diverse healthcare systems and cultural differences may be necessary for the widespread use of FBT.

Associations between Internet Addiction, Psychiatric Comorbidity, and Maternal Depression and Anxiety in Clinically Referred Children and Adolescents.

Purpose: Internet addiction (IA) has become a global problem and is one of the most common reasons for children to be referred for intervention because IA results in social and educational dysfunction and conflict with parents. IA is associated with various comorbid psychiatric disorders, with notable association between IA and family factors. However, little is known about parental psychopathology. This study aimed to examine the prevalence of IA and association between IA and maternal depression and anxiety in clinical samples after adjusting for comorbidities. Patients and Methods: A cross-sectional study was conducted between April 2020 and August 2021 at the Department of Neuropsychiatry of Osaka Metropolitan University Hospital in Japan. A total of 218 clinically referred children and adolescents (aged 8 to 15 years) were assessed using the Internet Addiction Test, which is one of the most popular questionnaires to evaluate IA, the Child Behavior Checklist (CBCL), and The Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version. IA was defined as a total score on the Internet Addiction Test ≥ 50. Of those, for the evaluation of maternal depression and anxiety, the 132 mothers of the children who were referred after January 2021 completed K6 as well. Results: A total of 68 participants (31.2%) presented with IA and had higher total and externalizing scores of CBCL, social anxiety disorder, and oppositional defiant disorder compared to those without IA. IA was associated with the six-item Kessler scale scores of mothers, being raised by single parents, and anxiety disorders after adjusting for age, sex, and family income (95% CI: 1.023-1.215). Conclusion: Maternal depression and anxiety may be one of the risk factors for children and adolescents to develop IA. Care for maternal depression and anxiety may contribute to intervention for children and adolescents with IA.

Associations Between Chronic Irritability and Sensory Processing Difficulties in Children and Adolescents.

Irritability is one of the most common reasons for which children and adolescents are referred for psychiatric evaluation and care. However, clinical irritability is difficult to define; thus, its prevalence varies widely. Chronic irritability may be associated with sensory processing difficulties (SPD), but little is known about the relationship between these two factors in clinical populations. In this study, we examined the prevalence of chronic irritability and its association with SPD in 166 children aged 5-16 years who were referred to the psychiatric outpatient clinic of the Osaka City University Hospital. Chronic irritability and parent-reported scores for the Short Sensory Profile, Infant Behavior Checklist-Revised, Child Behavior Checklist, and Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children (Present and Lifetime version) questionnaires were used for assessment. A total of 22 children (13.2%) presented with chronic irritability (i.e., the irritability group) and were more likely to have oppositional defiant disorder, externalizing problems, and attention issues than those without chronic irritability (i.e., the control group). SPD were reported in eight (36%) patients in the irritability group and in 21 (15%) in the control group (p = 0.029). Moreover, compared to the control group, the irritability group showed a significant difference in almost all items of the Short Sensory Profile. Chronic irritability was associated with more severe overall SPD, even after adjusting for possible confounding factors (internalizing and externalizing problems, age, sex, and low income). We provide evidence to support our hypothesis that chronic irritability is associated with SPD in children and adolescents. Therefore, SPD should be assessed to provide appropriate interventions in children and adolescents with chronic irritability.

COVID-19 phobia in a boy with undiagnosed autism spectrum disorder: A case report.

RATIONALE: Coronavirus disease 2019 (COVID-19) is affecting mental health profoundly. Previous studies have reported pandemic-related anxiety. Anxiety disorder and autism spectrum disorder (ASD) are common comorbidities. However, there has been no report of any patient with undiagnosed ASD who developed anxiety disorders caused by the COVID-19 pandemic. In this case report, we describe an 8-year-old Japanese boy with undiagnosed ASD who developed COVID-19 phobia, resulting in avoidant restrictive food intake disorder (ARFID). PATIENT CONCERNS: As COVID-19 was highly publicized in the mass media and the risk of droplet infection was emphasized upon, the patient began to fear viral contamination from food, culminating in a refusal to eat or even swallow his saliva. He was admitted to a pediatric medical center in Osaka with life-threatening dehydration and was then referred to our child psychiatry department. DIAGNOSIS: We diagnosed the patient with COVID-19 phobia resulting in ARFID. We identified ASD traits from his present social communication skills and developmental history. INTERVENTIONS: We provided psychoeducation of ASD for the parents and administered supportive psychotherapy. OUTCOMES: Shortly after our intervention to relieve his ASD-related anxiety, his dysphagia improved. LESSONS: Our findings suggest that children with undiagnosed ASD may develop COVID-19 phobia. In these cases, intervention for ASD may be more appropriate than starting treatment for anxiety disorders as the first-line option. COVID-19 is the biggest pandemic in the recent past, and more undiagnosed ASD patients who develop COVID-19 phobia may seek treatment. Clinicians should consider the underlying ASD in these patients and assess their developmental history and present social communication skills.

Introduction of family-based treatment to Japan with adaptations to optimize the cultural acceptability and advance current traditional treatments of adolescent anorexia nervosa.

Given the lack of clear consensus on effective treatment models for adolescent anorexia nervosa in Japan, treatment programs offered to this population vary widely between treatment facilities with limited testing of outcomes. Importantly, families have traditionally been left out of the core treatment process, as they are commonly viewed as being powerless in renourishing their child. The purpose of this commentary was to report the authors' preliminary efforts to introduce and implement family-based treatment (FBT) in Japan so that, on par with international standards of practice, FBT may become the first-line treatment option for Japanese families. This commentary will describe the systemic and cultural barriers which posed as challenges in introducing FBT to Japan in its manualized standard format and how these were addressed by introducing FBT during the patient's hospital admission and by assigning the father with a role which resembles the traditional gender role within the Japanese family culture. Authors have thus far observed that these adaptations led to increased accessibility of FBT and improved outcomes such as reduced number of hospitalizations and shorter time taken to reach 85-90% EBW. Further considerations for the broad dissemination and implementation of FBT in Japan are also presented.

Anorexia nervosa restricting type has increased in severity over three decades: Japanese clinical samples from 1988 to 2018.

OBJECTIVE: Although eating disorders (EDs) surged in the late 1900s and are now recognized worldwide, the time trend of ED characteristics remains unknown. This study aimed to clarify changes in characteristics of anorexia nervosa restricting type (AN-R) over 30 years. METHODS: We conducted a cross-sectional study and examined 996 female treatment-seeking patients with AN-R in Japan from 1988 to 2018. Demographics, body mass index (BMI), and Eating Disorder Inventory scores were compared among three groups in accordance with the time of initial consultation: Group 1 (1988-1998), Group 2 (1998-2008), Group 3 (2008-2018). RESULTS: The mean BMI at the initial consultation significantly decreased by 0.6 kg/m2 (from 14.0 kg/m2 in Group 1 to 13.4 kg/m2 in Group 3). Groups 2 and 3 scored significantly higher in drive for thinness, interpersonal distrust, and interoceptive awareness than those in Group 1. The range of onset age is wider and the number of late-onset AN-R with prolonged delay in treatment has increased over time. DISCUSSION: This study shows that AN-R has increased in physical and psychopathological severity over the past 30 years in Japan. Interdisciplinary research is needed to clarify the relationship between AN-R and time trend.

High prevalence of shoplifting in patients with eating disorders.

PURPOSE: Shoplifting, prevalent in patients diagnosed with bulimia nervosa (BN), is a serious behavioral problem in eating disorder (ED) patients. However, little is known about its overall presence, etiology, and consequences. This study aimed to determine whether shoplifting occurs before or after the onset of ED and to investigate the prevalence and correlates of shoplifting in ED patients. METHODS: This was a cross-sectional study of 284 treatment-seeking female patients aged 13-45 with EDs [171 anorexia nervosa (AN); 113 BN]. Shoplifting, impulsive behaviors (self-injury, suicide attempt, sexual promiscuity, alcohol, and illicit drug use), depression, self-esteem, and clinical features of EDs were assessed with an interview. RESULTS: Lifetime shoplifting prevalence was 28.5% (81/284) with 70.4% (57/81) occurring before ED onset. Multivariate logistic regression analysis revealed that depression [odds ratio (OR), 2.63; 95% confidence interval (CI), 1.24-5.60], alcohol abuse (OR, 3.91; 95% CI 1.34-11.38), illicit substance use (OR, 14.42; 95% CI, 1.65-125.86), and self-esteem (OR, 0.90; 95% CI; 0.82-0.99) were associated with lifetime shoplifting, while illness duration, BN, and ED symptom severity were not. CONCLUSIONS: Shoplifting is common in ED patients and precedes ED onset in most patients with a shoplifting history, although the causal relationship between shoplifting and EDs remains inconclusive. Shoplifting may be associated with impulsive behaviors (e.g., alcohol and illicit drug use), depression, and low self-esteem, but not with ED severity. Future research should focus on the unrecognized role of shoplifting as a marker to identify patients at risk of impulsive behaviors and consider treatment options. LEVEL OF EVIDENCE: Level V, observational cross-sectional descriptive study.

Preschool-onset obsessive-compulsive disorder with complete remission.

Early-onset obsessive-compulsive disorder (OCD) is more severe than later-onset OCD. There are no reports of any early-onset OCD patients being cured, especially with respect to preschoolers. In this case report, we describe the successful treatment and cure of a 6-year-old preschool girl with severe OCD since the age of 3. At the age of 3, the patient began to fear contamination and danger to herself and her family, leading to excessive hand-washing, and several months later, ritualized checking. The OCD symptoms waxed and waned for about 3 years and thereafter worsened gradually over a few weeks, culminating in a refusal to eat and dress. At the age of 6, after a week of inpatient pediatric treatment with no improvement, the patient was transferred to Osaka City University Hospital to seek psychiatric treatment. The patient fully recovered from OCD following family-based cognitive-behavioral therapy (CBT) and short-term use of low-dose fluvoxamine in an inpatient setting. After treatment, the OCD symptoms disappeared with complete remission for over 3 years. Now, aged 9, the patient has good global functioning and is well adjusted in her daily life with no need for any treatment. To the best of our knowledge, this is the first report of preschool-onset OCD with long-term complete remission with inpatient treatment in a preschooler with severe OCD. Some preschoolers with very early-onset OCD may have good prognosis without continuous pharmacotherapy, although the symptoms with the onset are severe enough to require hospitalization. Preschool-onset OCD is likely to be misdiagnosed as separation anxiety disorder. Our findings suggest that family-based CBT, which is the treatment of choice for preschool-onset OCD, can be applicable to inpatient treatment. Early detection and intensive intervention of OCD in preschoolers may improve the chance of remission.

Ontogenetic and temperature-dependent changes in tolerance to hypoxia and hydrogen sulfide during the early life stages of the Manila clam Ruditapes philippinarum.

Wind-induced upwelling of hypoxic waters containing hydrogen sulfide (H2S) sometimes causes mass mortalities of aquatic organisms inhabiting coastal areas, including the hypoxia-tolerant Manila clam Ruditapes philippinarum. We examined the tolerance of Manila clam to H2S under controlled laboratory conditions. Larvae and juveniles obtained by artificial fertilization or from a wild population were exposed to normoxic or to hypoxic water with or without un-ionized H2S (concentrations, 0.2-52.2 mg/L). Twenty-four-hour exposure experiments revealed ontogenetic changes in the clam's tolerance to H2S exposure: tolerance was enhanced from the larval stages to juveniles just after settlement but was attenuated as juveniles grew. Tolerance of larvae and juveniles to H2S exposure weakened as the water temperature rose from 20 to 28 °C. Prolonged 48-h exposure to H2S attenuated the tolerance of juveniles to H2S. Temporary suspension of H2S exposure by 24-h reoxygenation improved the ability of juveniles to withstand repeated H2S exposure.

Psychogenic nonepileptic seizures as a manifestation of psychological distress associated with undiagnosed autism spectrum disorder.

Psychogenic nonepileptic seizures (PNES) are observable changes in behavior or consciousness that are similar to epileptic seizures but are not associated with electrophysiologic changes. PNES occur in children with underlying psychological distress and are especially frequent in those with epilepsy. Because PNES are heterogeneous, comprehensive treatment tailored to each patient is required to reduce psychosocial stress. Currently, reports regarding children with PNES concomitant with autism spectrum disorder (ASD) do not exist, and effective treatment strategies for these children are lacking. In this case report, we describe a 10-year-old Japanese girl with undiagnosed ASD who developed PNES while undergoing treatment for benign childhood epilepsy with centrotemporal spikes. She exhibited hypersensitivity to sound and interpersonal conflicts caused by social communication deficits. The PNES symptoms improved shortly after our intervention, which was designed to reduce her distress caused by auditory hypersensitivity and impaired social communication, both characteristics of ASD. To the best of our knowledge, this is the first report describing PNES in a child with ASD. Our findings suggest that PNES can result from psychological distress in children with undiagnosed ASD and highlight the importance of examining ASD traits in patients with PNES.

Subclinical Manic Symptoms in Children with Autism Spectrum Disorder.

Background: Children with autism spectrum disorder (ASD) have varied comorbidities. With regard to comorbidity, there has been increasing interest in bipolar disorder (BP) in children. However, the prevalence of BP with ASD has varied because of the methodological differences used. Therefore the adequate criteria for determining BP in children are still debated. The purpose of this study is to identify reliable prevalence of BP and to evaluate a variety of subclinical BP symptoms in children with ASD. Methods: This is a cross-sectional and case-control study. The participants were 110 referred children aged 6-15 years: 46 with ASD (the case group), 64 without ASD (the control group). We used the strict operational criteria for diagnosing BP, and assessed the presence of subclinical BP symptoms using a semi-structured diagnostic interview. Results: None of the children were diagnosed with BP in the case group, although two children were diagnosed with BP in the control group. Based on the subclinical BP symptoms, the prevalence of elation/expansive mood and racing thoughts was significantly higher in the case group than in the control group: 26.1% versus 3.1% (p<.001) and 32.6% versus 9.4% (p=0.002), respectively. Conclusions: Our finding indicates that school-aged ASD children frequently present subclinical BP symptoms. It is important to be aware of over-diagnosis of BP, even though the children present subclinical BP symptoms, and to provide -the children with effective treatments.

High Prevalence of Non-psychotic Delusions in Children with High-functioning Pervasive Develonmental Disorder.

BACKGROUND: Non-psychotic delusions are reported to be associated with depression and anxiety. When these delusions occur in high-functioning pervasive developmental disorder (HFPDD) children, they are often misdiagnosed as schizophrenia and have consequently been studied less. This study has three goals: to investigate the prevalence of non-psychotic delusions in HFPDD children, to test the hypothesis that HFPDD children are more likely to have non-psychotic delusions than non-HFPDD children, and to test the hypothesis that non-psychotic delusions are associated with depression and anxiety. METHODS: This is a cross-sectional and case-control study. The participants were 45 HFPDD children (cases) and 51 children without HFPDD (controls). Semi-structured interviews were conducted to assess the presence of non-psychotic delusions. We used the Child Behavior Checklist (CBCL) to assess levels of anxiety and depression. RESULTS: Of the cases, 62.2% had non-psychotic delusions, which was significantly higher than controls (25.5%, p<0.001, OR: 4.81, 95% CI: 2.01-11.51). Cases tended to score higher for internalizing problems (including anxiety and depression) on the CBCL than controls (69.8±9.4 vs 65.9±10.4, t= 1.9, p=0.062). Cases with non-psychotic delusions scored significantly higher for internalizing problems in CBCL than children without non-psychotic delusions (72.2±7.7 vs 65.7±10.7, t=2.4, p= 0.022). CONCLUSIONS: More than half of the HFPDD children were suffering from non-psychotic delusions, and these delusions were associated with anxiety and depression. Therefore, accurate diagnoses of non-psychotic delusions should be conducted for appropriate treatments to be prescribed.

Psychiatric comorbidity in children with high-functioning pervasive developmental disorder.

BACKGROUND: In previous studies for children with pervasive developmental disorder (PDD), the prevalence for psychiatric comorbidities has varied because of their methodological differences. In this research, our PDD subjects were strictly limited by age and IQ scores, and we utilized a semi-structured interview to diagnose their coexisting disorders. The purpose of this study is to identify reliable prevalence and types of psychiatric comorbidities in children with high-functioning PDD (HFPDD). METHODS: The subjects were 49 children aged 6-15 years with HFPDD. In order to diagnose the comorbidities among them, we used the Japanese version of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime version. RESULTS: Forty-eight cases (98%) met the criteria for at least one comorbidity. The median number of the present comorbidities per child was 2, and the mode was 2. Depression (37%), attention deficit hyperactivity disorder (49%), and oppositional defiant disorder (45%) were frequently observed. CONCLUSIONS: Our finding indicates the high prevalence of comorbidities and the variety of the comorbid disorders in children with HFPDD. It is important to be aware of those comorbid disorders to provide the children with effective treatments.

Sensory hypersensitivity in children with high-functioning pervasive developmental disorder.

BACKGROUND: Studies have shown that children with pervasive developmental disorder (PDD) have high rates of sensory hypersensitivity. In addition, a few recent studies suggested that sensory hypersensitivity was related to anxiety or depression. However, most studies had methodological limitations because they included children with mental retardation and did not examine broadband psychopathology. Therefore, the purpose of this study was to examine the prevalence of sensory hypersensitivity in children with high-functioning PDD (HFPDD) and the correlation among sensory hypersensitivity, various characteristics, and broadband psychopathology. METHODS: We assessed 132 children with HFPDD (aged 6-15 years, 75% male) that were divided into sensory hypersensitivity (HS) and sensory non-hypersensitivity (non-HS) groups. A logistic regression model was used to examine correlations among sensory hypersensitivity, age, gender, PDD subtypes, socioeconomic status, and broadband psychopathology, including symptoms of anxiety and depression. RESULTS: Of the 132 children with HFPDD, 65.9% (n = 87) were categorized as HS and 34.1% (n = 45) as non-HS. The most common sensory hypersensitivity was auditory. Logistic regression analyses revealed that sensory hypersensitivity in HFPDD was significantly associated with autistic disorder and symptoms of anxiety and depression. CONCLUSIONS: Majority of children with HFPDD exhibited sensory hypersensitivity. Our findings suggested that sensory hypersensitivity may be a core feature of HFPDD and is possibly correlated to symptoms of anxiety and depression. We propose that sensory hypersensitivity in children with PDD should be aggressively assessed.

Anxiety in children with high-functioning pervasive developmental disorder.

BACKGROUND: Anxiety symptoms in children with pervasive developmental disorder (PDD) often appear to be not as severe as those in children with anxiety disorders or often appear to be the core features of PDD, and therefore, they do not meet the diagnostic criteria for anxiety disorders. In this study, we assessed anxiety broadly in line with dimensions of anxiety and not with an operational categorical diagnosis. The objective of this study was to reveal that children with high-functioning PDD have more anxiety than children in the general population. METHODS: Forty-six children with high-functioning PDD (6-15 years old) were assessed for total anxiety and six subcategories of anxiety, including separation anxiety, generalized anxiety, social phobia, panic/agoraphobia, physical injury fears, and obsessive-compulsiveness. Anxiety in children with high-functioning PDD was compared to that in children of the general population and to that in children with anxiety disorders in a previous study. RESULTS: Children with high-functioning PDD had significantly more symptoms of total anxiety and all subcategories of anxiety except for social phobias than children in the general population, and had significantly fewer symptoms of total anxiety, separation anxiety, generalized anxiety, and social phobias than children with anxiety disorders. CONCLUSIONS: As anxiety in children with high-functioning PDD does not always meet diagnostic criteria for an anxiety disorder, psychiatrists must pay much attention to anxiety and not only depend on diagnostic criteria in order to not miss the chance of treating these children.

Relationship of hypersensitivity to anxiety and depression in children with high-functioning pervasive developmental disorders.

AIMS: Sensory-perceptual abnormalities, which include hyper- and hyposensitivity, have been identified by numerous researchers as prevalent in individuals with pervasive developmental disorders (PDD). Hypersensitivity has a greater impact on PDD patients' daily lives than hyposensitivity. The purpose of the present study was to clarify the relationship of hypersensitivity to anxiety, depression and other psychopathology in children with PDD. METHODS: Sixty-four children were divided into a hypersensitivity group (HG; n = 43) and a non-hypersensitivity group (non-HG; n = 21), and compared for anxiety, depression and other psychopathology on the Child Behavior Checklist (CBCL), State-Trait Anxiety Inventory for Children (STAIC) and Children's Depression Inventory (CDI). RESULTS: The HG group had significantly higher scores than the non-HG group in Total, Internalizing, and Somatic complaints on the CBCL. On STAIC, the mean sore of Total Score, State Score and Trait Score in the HG group tended to be higher than in the non-HG group, but the difference was not significant. The score on the CDI in the HG group was significantly higher than that in the non-HG group. CONCLUSION: PDD children with hypersensitivity have more serious psychopathologies, especially internalizing symptoms including depression.

Evaluation of attention-deficit/hyperactivity disorder symptoms in male children with high-functioning pervasive developmental disorders.

BACKGROUND: Although there are many reports of high rates of hyperactivity and attention deficits in children with Pervasive Developmental Disorders (PDD), controversy remains about the applicability of the diagnosis of Attention-Deficit/Hyperactivity Disorder (ADHD) to PDD children. The present study elucidates the similarities and differences of ADHD symptoms in PDD children compared to ADHD children. METHODS: Twenty-seven male children with PDD+ADHD Combined type (ADHD-C), 17 males with ADHD-C, and 9 males with PDD without ADHD-C, were compared on measures of ADHD symptoms and related behaviors using parent ratings and teacher ratings on the ADHD Rating Scale (ADHDRS), the Child Behavior Checklist (CBCL) and the Teacher Report Form (TRF). RESULTS: The PDD+ADHD-C and the ADHD-C groups had significantly higher ratings than the PDD only group for all the scores on both the parent-rated and the teacher-rated ADHDRS. The ADHD-C and PDD+ADHD-C groups had significantly higher scores than the PDD group on Delinquent Behavior, Aggressive Behavior, and Externalizing Behavior of the CBCL and on Delinquent Behavior of the TRF; there were no significant differences between the ADHD-C and PDD+ADHD-C groups on any scores of the CBCL and TRF. CONCLUSIONS: The PDD+ADHD-C and ADHD-C groups share a similar profile of ADHD symptoms and externalizing behaviors, and the comorbidity of ADHD and PDD should be suspected when ADHD symptoms are present in PDD children.

Hyperactivity and comorbidity in Japanese children with attention-deficit/hyperactivity disorder.

No previous study about comorbidity of attention-deficit/hyperactivity disorder (ADHD) in Japan have carried out both a comprehensive investigation using a structured interview and a comparison between ADHD subtypes. The aim of the present study was to clarify the relationship between hyperactivity and disruptive behavior disorder (DBD) in ADHD by comparing a hyperactivity group (HG) with a non-hyperactivity group (non-HG). After diagnosis was carried out by strict exclusion, the 41 ADHD subjects (6-14 years old; IQ, 70-121) diagnosed according to DSM-IV were divided into HG (n = 24) and non-HG (n = 17), and compared for comorbidities and psychopathologies. This was done via semistructured interview with children and parents and questionnaires to parents and teachers. The results demonstrate that (i) most ADHD children had comorbidity (e.g. DBD or anxiety disorder); (ii) the HG had a significantly higher rate of DBD than the non-HG, but the total number of anxiety disorders was not different between subgroups, and (iii) the HG generally had more serious psychopathologies both at home and at school than the non-HG. Both groups had more serious externalizing and internalizing problems at home than at school. The present study provides evidence of a strong relationship between hyperactivity and DBD.