- Email: [email protected]
hyperactivity disorder distinct disorders?
Brain & Development 28 (2006) 371–374 www.elsevier.com/locate/braindev
Original article
Are pervasive developmental disorders and attention-deficit/hyperactivity disorder distinct disorders? Junri Hattori *, Tatsuya Ogino, Kiyoko Abiru, Kousuke Nakano, Makio Oka, Yoko Ohtsuka Department of Child Neurology, Okayama University Graduate School of Medicine and Dentistry, Shikata-cho 2-5-1, Okayama 700-8558, Japan Received 30 April 2005; received in revised form 13 October 2005; accepted 26 November 2005
Abstract We studied the relationship between patients with attention-deficit/hyperactivity disorder (ADHD) and those with pervasive developmental disorders (PDD), using the High-Functioning Autism Spectrum Screening Questionnaire (ASSQ) and ADHD Rating Scale-IV. The ASSQ scores of the PDD group and the ADHD group were significantly higher than the control group. Furthermore, the PDD group scored higher than the ADHD group. Both groups also showed higher scores than the control group in all three domains, that is, restricted and repetitive behavior, social interaction, and communication problem. The PDD and the ADHD group showed no significant difference in the domains of communication problem, and restricted and repetitive behavior. The PDD group had a higher score than the ADHD group only in the social interaction domain. In total score, inattention score, and hyperactivity/impulsivity score on the ADHD Rating Scale-IV, both groups were significantly higher than the control group. Between the ADHD and the PDD groups, there was no significant difference in the three scores. The patients with strictly diagnosed ADHD had many PDD-related symptoms, and the patients with PDD had many ADHD-related symptoms. It therefore seems difficult to make a distinction between ADHD and PDD by using the present diagnostic criteria in the DSM-IV. We should evaluate each patient in terms of both sets of criteria. q 2005 Elsevier B.V. All rights reserved. Keywords: Attention-deficit/hyperactivity disorder; Pervasive development disorders
We often find that patients diagnosed with attentiondeficit/hyperactivity disorder (ADHD) have symptoms similar to those of pervasive developmental disorders (PDD) and vice versa, so differentiation between these two disorders is often difficult. We previously reported that many of the patients with PDD met the DSM-IV [1] criteria for ADHD [2]. It has also been reported that disorders of ‘theory of mind’, or social competence, were observed in the patients with ADHD [3]. So to make clear whether both disorders are distinctly different, we evaluated PDD-related symptoms and ADHD-related symptoms in the patients with PDD or ADHD and compared them by using common scales.
* Corresponding author. Fax: C81 86 235 7377. E-mail address: [email protected] (J. Hattori).
0387-7604/$ - see front matter q 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.braindev.2005.11.009
1. Subjects and method 1.1. Subjects The subjects were 35 children who had been referred to the outpatient clinic of the department of child neurology at Okayama University Hospital. Twenty of the 35 (19 boys and one girl; 5–15 years, mean: 9 years 4 months) were diagnosed as having ADHD. None of them met the DSM-IV criteria for PDD. The chief complaints of the initial visit were restlessness in 13 patients, distractibility in three, failure to develop peer relationships in two, ill-tempered in one, and forgetfulness in one. Of the 20 patients, 12 were classified as the combined type, seven as the predominantly inattentive type, and one as the predominantly hyperactive/impulsive type. As comorbid disorders, three patients had oppositional defiant disorder, two had rage attack, and one had obsessive compulsive disorder. Thirteen of the 20 were given the WISC-III, and their mean Full Scale IQ was 89. Fifteen (nine boys and six girls; 5–13 years, mean: 8 years 8 months) of the 35 children had PDD. The chief
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complaints of the initial visit were failure to develop peer relationships in four patients, stealing money in one, restlessness in three, difficulty in sustaining attention in one, language developmental delay in two, one-way conversation in one, panic in one, and restricted and repetitive behavior in two. Five patients were diagnosed as having an autistic disorder, five as having Asperger’s disorder, and five as having a pervasive developmental disorder not otherwise specified. One patient had tic disorder as a comorbid disorder. Eight of these 15 patients were given the WISC-III, and their mean Full Scale IQ was 86. All of them could express themselves efficiently enough in their daily lives. The diagnoses of ADHD and PDD were made according to the DSM-IV. When we made a diagnosis, we observed the children’s behavior and interviewed their parents systematically in one to three 90-min sessions. As the control group, 40 normal children (38 boys and 2 girls; 5–15 years, mean: 9 years 4 months) took part in this study. All of them underwent the Japanese version of the Child Behavior Checklist (CBCL) [4,5], and their T scores from the internalizing, externalizing, and total problem scores were lower than 63. The statistical analysis using ANOVA revealed no significant difference in age among these three groups. By the c2K test, the distributions by sex differed significantly. More girls were in the PDD group than in the other two groups (PZ0.001). There was no significant difference between the ADHD group and the PDD group in Full Scale IQ.
1.2. Method We asked the parents of the subjects to answer two checklists, and we compared the scores of the three groups. To assess the symptoms related to PDD, we used the HighFunctioning Autism Spectrum Screening Questionnaire (ASSQ) [6,7]. The scoring range in this questionnaire is 0–54 per subject, and the higher the score, the more the subject has symptoms related to PDD. Although only one score is usually derived from the ASSQ, we classified ASSQ items into three domains, that is, restricted and repetitive behavior (items 2, 3, 9, 10, 18, 20, 21, 22, 23, 24, 27); social interaction (items 1, 12, 14, 15, 16, 17, 19, 25, 26); and communication problem (items 4, 5, 6, 7, 8, 11, 13) [7]. After two child neurologists (Hattori and Ogino) classified independently every ASSQ item into the respective domains, the items they had classified differently were classified into one of three domains after discussion and agreement. To assess the symptoms related to ADHD, we used the ADHD Rating Scale-IV for parents [8] that we had translated into Japanese. The scoring range in this questionnaire is 0–54 per subject, and the higher the score, the more the subject has symptoms related to ADHD. Three scores are derived from the ADHD Rating Scale-IV,
that is, the inattention score, the hyperactivity/impulsivity score, and the total score, which is the sum of inattention score and hyperactivity/impulsivity score. We compared each score among the three groups. To evaluate the differences in the ASSQ and ADHD Rating Scale-IV scores of the three groups, the Kruskal– Wallis test was used. If the difference was significant, a multiple comparison was made, using the Mann–Whitney test. The significance level was P!0.05. The significance level of the Mann–Whitney test for a multiple comparison with Bonferroni correction was P!0.05/3.
2. Results 2.1. ASSQ 2.1.1. Total score The mean total score of the ASSQ was the highest in the PDD group (21.7), next highest in the ADHD group (14.8), and lowest in the control group (4.3). Using the Kruskal– Wallis test, we noted significant differences in the ASSQ total scores (P!0.001) of the three groups. A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001), the ADHD group and the PDD group (PZ0.016), and the PDD group and the control group (P!0.001). The ADHD group lay between the control group and the PDD group (Table 1). 2.1.2. Domain-specific scores The mean social interaction score was 8.1 in the PDD group, 5.4 in the ADHD group, and 1.2 in the control group. The mean communication problem score was 5.7 in the PDD group, 3.6 in the ADHD group, and 1.3 in the control group. The mean restricted and repetitive behavior score was 7.9 in the PDD group, 5.8 in the ADHD group, and 1.9 in the control group. Thus the ADHD group scored between the control group and the PDD group in all three domains. Using the Kruskal–Wallis test, we noted significant differences (P!0.001) among the three groups in all three domain-specific scores. Next, a multiple comparison revealed significant differences in the social interaction domain between all paired combinations of the three groups. However, in the communication problem domain and the restricted and repetitive behavior domain, there were significant differences between the ADHD group and the control group (P%0.001) and the PDD group and the Table 1 Total score of ASSQ Group ADHD PDD Control
(Mean; mean rank) * **
**
*P!0.016, **PZ0.001 (Mann–Whitney).
(14.8; 48.5) (21.7; 60.8) (4.3; 24.2)
J. Hattori et al. / Brain & Development 28 (2006) 371–374
373
Table 2 Domain-specific scores of ASSQ Group ADHD PDD Control
Social interaction (mean; mean rank) *
**
**
Communication problem (mean; mean rank) (5.4; 49.8) (8.1; 61.4) (1.2; 23.4)
**
**
Restricted and repetitive behavior (mean; mean rank) (3.6; 45.3) (5.7; 58.4) (1.3; 26.7)
**
**
(5.8; 46.3) (7.9; 57.6) (1.9; 26.5)
*PZ0.016, **P%0.001 (Mann–Whitney).
control group (P!0.001), but not between the ADHD group and the PDD group (Table 2). The ASSQ total score and the three domain-specific scores showed no significant differences among the subtypes of PDD (autistic disorder, Asperger’s disorder, and PDD-NOS) by the Kruskal–Wallis test. 2.2. ADHD rating scale-IV 2.2.1. Total score The mean total score on the ADHD Rating Scale-IV was highest in the ADHD group (25.7), next highest in the PDD group (19.1), and lowest in the control group (7.5). Using the Kruskal–Wallis test, we noted significant differences in the total ADHD Rating Scale-IV scores of the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (P!0.001). None was noted between the ADHD group and the PDD group (Table 3). 2.2.2. Inattention score The mean inattention score on the ADHD Rating Scale-IV was highest in the ADHD group (14.8), next highest in the PDD group (11.4), and lowest in the control group (5.0). There were significant differences between the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (PZ0.001), but not between the ADHD group and the PDD group (Table 4). 2.2.3. Hyperactivity/impulsivity score The mean hyperactivity/impulsivity score on the ADHD Rating Scale-IV was highest in the ADHD group (10.9), next highest in the PDD group (7.7), and lowest in the control group (2.6). There were significant differences between the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (PZ0.002), but not between the ADHD group and the PDD group (Table 4).
3. Discussion According to the DSM-IV criteria for ADHD, PDD is placed in the exclusion criteria of ADHD. In this study, the subjects who had PDD, according to the DSM-IV criteria, were excluded from the ADHD group. However, the ASSQ total score in the ADHD group was higher than in the control group. Moreover, all three domain-specific scores (social interaction, communication problem, and restricted and repetitive behavior) were higher in the ADHD group than in the control group. In the ADHD group, every ASSQ domain score was between those of the PDD and the control groups. These results may indicate that rather than having ADHD distinct from PDD, the ADHD group consisted of subjects whose PDD-related symptoms did not reach the threshold of DSM-IV criteria for PDD. There was a significant difference between the PDD group and the ADHD group in the ASSQ total score. However, concerning the three domain-specific scores, the differences between the two groups became unclear, and a significant difference was noted only in the social interaction score. The reason why there was significant difference between the PDD group and the ADHD group in only the social interaction domain is not clear. It may have been that the diagnosis of autism or Asperger’s disorder according to DSM-IV criteria requires more than two items in the social interaction domain, but only one in the other domains. When PDD was diagnosed in children according to the DSM-IV criteria, ADHD criteria was not taken into consideration. The PDD group’s scores in the total score, inattention score, and hyperactivity/impulsivity score categories of the ADHD Rating Scale-IV were between the ADHD group and the control group. The PDD group scored significantly higher in every category of the ADHD Rating Scale-IV than the control group did. This indicates that the children diagnosed with PDD had considerable
Table 3 Total score on ADHD Rating Scale-IV Group ADHD PDD Control
(Mean; mean rank)
*
*P!0.001 (Mann–Whitney).
*
(25.7; 57.8) (19.1; 47.0) (7.5; 24.8)
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Table 4 Inattention and hyperactivity/impulsivity score on ADHD Rating Scale-IV Group ADHD PDD Control
Inattention (mean; mean rank)
**
**
Hyperactivity/impulsivity (mean; mean rank) (14.8; 56.2) (11.4; 46.6) (5.0; 25.7)
*
**
(10.9; 56.7) (7.7; 46.7) (2.6; 25.6)
*P%0.001, **PZ0.002 (Mann–Whitney).
ADHD-related symptoms. On the other hand, the PDD group and the ADHD group had no significant scoring differences on the ADHD Rating Scale-IV. Thus it seems that the PDD group was more similar to the ADHD group than to the control group. Previously, we reported that many patients with PDD met the DSM-IV criteria for ADHD [2]. Frazier et al. [9] and Goldstein and Schwebach [10] have also reported that ADHD symptoms were observed in many PDD children. These authors reported that children with both PDD and ADHD were significantly more likely to require medication, psychotherapy, or hospitalization than children with only PDD [9]. Frazier et al. [9] have demonstrated that PDD symptoms in PDD children with ADHD were similar to those of PDD children without ADHD, and that ADHD symptoms in ADHD children with PDD were similar to those of ADHD children without PDD. That is, by paying attention to each symptom, we cannot distinguish patients with both PDD and ADHD symptoms from patients with only one of these symptoms. In this study, the clinical symptoms of children with ADHD and those of children with PDD overlapped, and the boundary between the two disorders was unclear. It is difficult to distinguish them, based on the behavioral characteristics, with only the present, operationally defined criteria. As Frazier et al. proposed, comorbid diagnosis should be considered. Gillberg has argued that quite often children with severe deficits in attention, motor control, and perception (DAMP) exhibit social impairments, semantic pragmatic problems, and restricted–stereotyped–repetitive–obsessive behavior patterns, and there are no clear boundaries between autism, Asperger syndrome, semantic pragmatic disorders, and DAMP [11]. Moreover, Kaplan et al. have done research on reading disability, ADHD, developmental coordination disorder, oppositional defiant disorder, conduct disorder, depression, and anxiety, and they reported that 52% of their sample met the criteria for at least two diagnoses. In particular, 80% of those with ADHD had at least one other disorder. They have proposed using the term atypical brain development to refer to a series of developmental disorders rather than the term comorbidity and argue that one should look at the overlapping problems by using broad-based assessments rather than focusing on single-skill areas [12]. In reality, it is difficult to make clear the boundaries between the individual concepts of developmental disorders based on
single-skill assessments. In clinical practice and research on developmental disorders, not only categorical diagnosis, but also dimensional diagnosis should be considered [13]. By doing so, we will be able to evaluate each patient from multidimensional aspects and to plan more-efficient treatment strategies.
References [1] American Psychiatric Association. Diagnostic and statistical manual of mental disorder. Text revision. 4th ed. Washington, DC: American Psychiatric Association; 2000. [2] Ogino T, Hattori J, Abiru K, Nakano K, Oka E, Ohtsuka Y. Symptoms related to ADHD observed in patients with pervasive developmental disorder. Brain Dev; in press. [3] Buitelaar JK, van der Wees M, Swaab-Barneveld H, van der Gaag RJ. Theory of mind and emotion–recognition functioning in autistic spectrum disorders and in psychiatric control and normal children. Dev Psychopathol 1999;11:39–58. [4] Achenbach TM. Manual for the child behavior checklist/4-18 and profile. Burlington, VT: University of Vermont; 1991. [5] Itani T, Kanbayashi Y, Nakata Y, Kita M, Fujii H, Kuramoto H, et al. Standardization of the Japanese version of the child behavior checklist/4-18. Psychiatr Neurol Pediatr Jpn 2001;41:243–52. [6] Ii T, Hayashi E, Hirose Y, Tojo Y. The high-functioning autism spectrum screening questionnaire (in Japanese). In: Tojo Y, editor. Reports of Grants-in-Aid for Scientific Research (B) (2) (#13410042). Tokyo: The National Institute of Special Education; 2003. [7] Ehlers S, Gillberg C, Wing L. A screening questionnaire for Asperger syndrome and other high-functioning autism spectrum disorders in school age children. J Autism Dev Disord 1999;29:129–41. [8] DuPaul GJ, Power TJ, Anastopoulos AD, Reid R. ADHD Rating Scale-IV. Checklists, norms, and clinical interpretation. New York: Guilford Press; 1998. [9] Frazier JA, Biederman J, Bellordre CA, Garfield SB, Geller DA, Coffey BJ, et al. Should the diagnosis of attention-deficit/hyperactivity disorder be considered in children with pervasive developmental disorder? J Atten Disord 2001;4:203–11. [10] Goldstein S, Schwebach AJ. The comorbidity of pervasive developmental disorder and attention deficit hyperactivity disorder: results of a retrospective chart review. J Autism Dev Disord 2004;34:329–39. [11] Gillberg CL. Autism and autistic-like conditions: subclasses among disorders of empathy. J Child Psychol Psychiatry 1992;33:813–42. [12] Kaplan BJ, Dewey DM, Crawford SG, Wilson BN. The term comorbidity is of questionable value in reference to developmental disorders: data and theory. J Learn Disabil 2001;34:555–65. [13] Kraemer HC, Noda A, O’Hara R. Categorical versus dimensional approaches to diagnosis: methodological challenges. J Psychiatr Res 2004;38:17–25.
Original article
Are pervasive developmental disorders and attention-deficit/hyperactivity disorder distinct disorders? Junri Hattori *, Tatsuya Ogino, Kiyoko Abiru, Kousuke Nakano, Makio Oka, Yoko Ohtsuka Department of Child Neurology, Okayama University Graduate School of Medicine and Dentistry, Shikata-cho 2-5-1, Okayama 700-8558, Japan Received 30 April 2005; received in revised form 13 October 2005; accepted 26 November 2005
Abstract We studied the relationship between patients with attention-deficit/hyperactivity disorder (ADHD) and those with pervasive developmental disorders (PDD), using the High-Functioning Autism Spectrum Screening Questionnaire (ASSQ) and ADHD Rating Scale-IV. The ASSQ scores of the PDD group and the ADHD group were significantly higher than the control group. Furthermore, the PDD group scored higher than the ADHD group. Both groups also showed higher scores than the control group in all three domains, that is, restricted and repetitive behavior, social interaction, and communication problem. The PDD and the ADHD group showed no significant difference in the domains of communication problem, and restricted and repetitive behavior. The PDD group had a higher score than the ADHD group only in the social interaction domain. In total score, inattention score, and hyperactivity/impulsivity score on the ADHD Rating Scale-IV, both groups were significantly higher than the control group. Between the ADHD and the PDD groups, there was no significant difference in the three scores. The patients with strictly diagnosed ADHD had many PDD-related symptoms, and the patients with PDD had many ADHD-related symptoms. It therefore seems difficult to make a distinction between ADHD and PDD by using the present diagnostic criteria in the DSM-IV. We should evaluate each patient in terms of both sets of criteria. q 2005 Elsevier B.V. All rights reserved. Keywords: Attention-deficit/hyperactivity disorder; Pervasive development disorders
We often find that patients diagnosed with attentiondeficit/hyperactivity disorder (ADHD) have symptoms similar to those of pervasive developmental disorders (PDD) and vice versa, so differentiation between these two disorders is often difficult. We previously reported that many of the patients with PDD met the DSM-IV [1] criteria for ADHD [2]. It has also been reported that disorders of ‘theory of mind’, or social competence, were observed in the patients with ADHD [3]. So to make clear whether both disorders are distinctly different, we evaluated PDD-related symptoms and ADHD-related symptoms in the patients with PDD or ADHD and compared them by using common scales.
* Corresponding author. Fax: C81 86 235 7377. E-mail address: [email protected] (J. Hattori).
0387-7604/$ - see front matter q 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.braindev.2005.11.009
1. Subjects and method 1.1. Subjects The subjects were 35 children who had been referred to the outpatient clinic of the department of child neurology at Okayama University Hospital. Twenty of the 35 (19 boys and one girl; 5–15 years, mean: 9 years 4 months) were diagnosed as having ADHD. None of them met the DSM-IV criteria for PDD. The chief complaints of the initial visit were restlessness in 13 patients, distractibility in three, failure to develop peer relationships in two, ill-tempered in one, and forgetfulness in one. Of the 20 patients, 12 were classified as the combined type, seven as the predominantly inattentive type, and one as the predominantly hyperactive/impulsive type. As comorbid disorders, three patients had oppositional defiant disorder, two had rage attack, and one had obsessive compulsive disorder. Thirteen of the 20 were given the WISC-III, and their mean Full Scale IQ was 89. Fifteen (nine boys and six girls; 5–13 years, mean: 8 years 8 months) of the 35 children had PDD. The chief
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complaints of the initial visit were failure to develop peer relationships in four patients, stealing money in one, restlessness in three, difficulty in sustaining attention in one, language developmental delay in two, one-way conversation in one, panic in one, and restricted and repetitive behavior in two. Five patients were diagnosed as having an autistic disorder, five as having Asperger’s disorder, and five as having a pervasive developmental disorder not otherwise specified. One patient had tic disorder as a comorbid disorder. Eight of these 15 patients were given the WISC-III, and their mean Full Scale IQ was 86. All of them could express themselves efficiently enough in their daily lives. The diagnoses of ADHD and PDD were made according to the DSM-IV. When we made a diagnosis, we observed the children’s behavior and interviewed their parents systematically in one to three 90-min sessions. As the control group, 40 normal children (38 boys and 2 girls; 5–15 years, mean: 9 years 4 months) took part in this study. All of them underwent the Japanese version of the Child Behavior Checklist (CBCL) [4,5], and their T scores from the internalizing, externalizing, and total problem scores were lower than 63. The statistical analysis using ANOVA revealed no significant difference in age among these three groups. By the c2K test, the distributions by sex differed significantly. More girls were in the PDD group than in the other two groups (PZ0.001). There was no significant difference between the ADHD group and the PDD group in Full Scale IQ.
1.2. Method We asked the parents of the subjects to answer two checklists, and we compared the scores of the three groups. To assess the symptoms related to PDD, we used the HighFunctioning Autism Spectrum Screening Questionnaire (ASSQ) [6,7]. The scoring range in this questionnaire is 0–54 per subject, and the higher the score, the more the subject has symptoms related to PDD. Although only one score is usually derived from the ASSQ, we classified ASSQ items into three domains, that is, restricted and repetitive behavior (items 2, 3, 9, 10, 18, 20, 21, 22, 23, 24, 27); social interaction (items 1, 12, 14, 15, 16, 17, 19, 25, 26); and communication problem (items 4, 5, 6, 7, 8, 11, 13) [7]. After two child neurologists (Hattori and Ogino) classified independently every ASSQ item into the respective domains, the items they had classified differently were classified into one of three domains after discussion and agreement. To assess the symptoms related to ADHD, we used the ADHD Rating Scale-IV for parents [8] that we had translated into Japanese. The scoring range in this questionnaire is 0–54 per subject, and the higher the score, the more the subject has symptoms related to ADHD. Three scores are derived from the ADHD Rating Scale-IV,
that is, the inattention score, the hyperactivity/impulsivity score, and the total score, which is the sum of inattention score and hyperactivity/impulsivity score. We compared each score among the three groups. To evaluate the differences in the ASSQ and ADHD Rating Scale-IV scores of the three groups, the Kruskal– Wallis test was used. If the difference was significant, a multiple comparison was made, using the Mann–Whitney test. The significance level was P!0.05. The significance level of the Mann–Whitney test for a multiple comparison with Bonferroni correction was P!0.05/3.
2. Results 2.1. ASSQ 2.1.1. Total score The mean total score of the ASSQ was the highest in the PDD group (21.7), next highest in the ADHD group (14.8), and lowest in the control group (4.3). Using the Kruskal– Wallis test, we noted significant differences in the ASSQ total scores (P!0.001) of the three groups. A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001), the ADHD group and the PDD group (PZ0.016), and the PDD group and the control group (P!0.001). The ADHD group lay between the control group and the PDD group (Table 1). 2.1.2. Domain-specific scores The mean social interaction score was 8.1 in the PDD group, 5.4 in the ADHD group, and 1.2 in the control group. The mean communication problem score was 5.7 in the PDD group, 3.6 in the ADHD group, and 1.3 in the control group. The mean restricted and repetitive behavior score was 7.9 in the PDD group, 5.8 in the ADHD group, and 1.9 in the control group. Thus the ADHD group scored between the control group and the PDD group in all three domains. Using the Kruskal–Wallis test, we noted significant differences (P!0.001) among the three groups in all three domain-specific scores. Next, a multiple comparison revealed significant differences in the social interaction domain between all paired combinations of the three groups. However, in the communication problem domain and the restricted and repetitive behavior domain, there were significant differences between the ADHD group and the control group (P%0.001) and the PDD group and the Table 1 Total score of ASSQ Group ADHD PDD Control
(Mean; mean rank) * **
**
*P!0.016, **PZ0.001 (Mann–Whitney).
(14.8; 48.5) (21.7; 60.8) (4.3; 24.2)
J. Hattori et al. / Brain & Development 28 (2006) 371–374
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Table 2 Domain-specific scores of ASSQ Group ADHD PDD Control
Social interaction (mean; mean rank) *
**
**
Communication problem (mean; mean rank) (5.4; 49.8) (8.1; 61.4) (1.2; 23.4)
**
**
Restricted and repetitive behavior (mean; mean rank) (3.6; 45.3) (5.7; 58.4) (1.3; 26.7)
**
**
(5.8; 46.3) (7.9; 57.6) (1.9; 26.5)
*PZ0.016, **P%0.001 (Mann–Whitney).
control group (P!0.001), but not between the ADHD group and the PDD group (Table 2). The ASSQ total score and the three domain-specific scores showed no significant differences among the subtypes of PDD (autistic disorder, Asperger’s disorder, and PDD-NOS) by the Kruskal–Wallis test. 2.2. ADHD rating scale-IV 2.2.1. Total score The mean total score on the ADHD Rating Scale-IV was highest in the ADHD group (25.7), next highest in the PDD group (19.1), and lowest in the control group (7.5). Using the Kruskal–Wallis test, we noted significant differences in the total ADHD Rating Scale-IV scores of the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (P!0.001). None was noted between the ADHD group and the PDD group (Table 3). 2.2.2. Inattention score The mean inattention score on the ADHD Rating Scale-IV was highest in the ADHD group (14.8), next highest in the PDD group (11.4), and lowest in the control group (5.0). There were significant differences between the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (PZ0.001), but not between the ADHD group and the PDD group (Table 4). 2.2.3. Hyperactivity/impulsivity score The mean hyperactivity/impulsivity score on the ADHD Rating Scale-IV was highest in the ADHD group (10.9), next highest in the PDD group (7.7), and lowest in the control group (2.6). There were significant differences between the three groups (P!0.001). A multiple comparison revealed significant differences between the ADHD group and the control group (P!0.001) and between the PDD group and the control group (PZ0.002), but not between the ADHD group and the PDD group (Table 4).
3. Discussion According to the DSM-IV criteria for ADHD, PDD is placed in the exclusion criteria of ADHD. In this study, the subjects who had PDD, according to the DSM-IV criteria, were excluded from the ADHD group. However, the ASSQ total score in the ADHD group was higher than in the control group. Moreover, all three domain-specific scores (social interaction, communication problem, and restricted and repetitive behavior) were higher in the ADHD group than in the control group. In the ADHD group, every ASSQ domain score was between those of the PDD and the control groups. These results may indicate that rather than having ADHD distinct from PDD, the ADHD group consisted of subjects whose PDD-related symptoms did not reach the threshold of DSM-IV criteria for PDD. There was a significant difference between the PDD group and the ADHD group in the ASSQ total score. However, concerning the three domain-specific scores, the differences between the two groups became unclear, and a significant difference was noted only in the social interaction score. The reason why there was significant difference between the PDD group and the ADHD group in only the social interaction domain is not clear. It may have been that the diagnosis of autism or Asperger’s disorder according to DSM-IV criteria requires more than two items in the social interaction domain, but only one in the other domains. When PDD was diagnosed in children according to the DSM-IV criteria, ADHD criteria was not taken into consideration. The PDD group’s scores in the total score, inattention score, and hyperactivity/impulsivity score categories of the ADHD Rating Scale-IV were between the ADHD group and the control group. The PDD group scored significantly higher in every category of the ADHD Rating Scale-IV than the control group did. This indicates that the children diagnosed with PDD had considerable
Table 3 Total score on ADHD Rating Scale-IV Group ADHD PDD Control
(Mean; mean rank)
*
*P!0.001 (Mann–Whitney).
*
(25.7; 57.8) (19.1; 47.0) (7.5; 24.8)
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Table 4 Inattention and hyperactivity/impulsivity score on ADHD Rating Scale-IV Group ADHD PDD Control
Inattention (mean; mean rank)
**
**
Hyperactivity/impulsivity (mean; mean rank) (14.8; 56.2) (11.4; 46.6) (5.0; 25.7)
*
**
(10.9; 56.7) (7.7; 46.7) (2.6; 25.6)
*P%0.001, **PZ0.002 (Mann–Whitney).
ADHD-related symptoms. On the other hand, the PDD group and the ADHD group had no significant scoring differences on the ADHD Rating Scale-IV. Thus it seems that the PDD group was more similar to the ADHD group than to the control group. Previously, we reported that many patients with PDD met the DSM-IV criteria for ADHD [2]. Frazier et al. [9] and Goldstein and Schwebach [10] have also reported that ADHD symptoms were observed in many PDD children. These authors reported that children with both PDD and ADHD were significantly more likely to require medication, psychotherapy, or hospitalization than children with only PDD [9]. Frazier et al. [9] have demonstrated that PDD symptoms in PDD children with ADHD were similar to those of PDD children without ADHD, and that ADHD symptoms in ADHD children with PDD were similar to those of ADHD children without PDD. That is, by paying attention to each symptom, we cannot distinguish patients with both PDD and ADHD symptoms from patients with only one of these symptoms. In this study, the clinical symptoms of children with ADHD and those of children with PDD overlapped, and the boundary between the two disorders was unclear. It is difficult to distinguish them, based on the behavioral characteristics, with only the present, operationally defined criteria. As Frazier et al. proposed, comorbid diagnosis should be considered. Gillberg has argued that quite often children with severe deficits in attention, motor control, and perception (DAMP) exhibit social impairments, semantic pragmatic problems, and restricted–stereotyped–repetitive–obsessive behavior patterns, and there are no clear boundaries between autism, Asperger syndrome, semantic pragmatic disorders, and DAMP [11]. Moreover, Kaplan et al. have done research on reading disability, ADHD, developmental coordination disorder, oppositional defiant disorder, conduct disorder, depression, and anxiety, and they reported that 52% of their sample met the criteria for at least two diagnoses. In particular, 80% of those with ADHD had at least one other disorder. They have proposed using the term atypical brain development to refer to a series of developmental disorders rather than the term comorbidity and argue that one should look at the overlapping problems by using broad-based assessments rather than focusing on single-skill areas [12]. In reality, it is difficult to make clear the boundaries between the individual concepts of developmental disorders based on
single-skill assessments. In clinical practice and research on developmental disorders, not only categorical diagnosis, but also dimensional diagnosis should be considered [13]. By doing so, we will be able to evaluate each patient from multidimensional aspects and to plan more-efficient treatment strategies.
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