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hyperactivity disorder: cognitive profile at school age and its relationship to preschool indicators of language delay
Research in Developmental Disabilities 31 (2010) 1–8
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Research in Developmental Disabilities
Clinic attenders with autism or attention-deficit/ hyperactivity disorder: cognitive profile at school age and its relationship to preschool indicators of language delay Bibbi S. Hagberg *, Carmela Miniscalco, Christopher Gillberg Department of Child and Adolescent Psychiatry, Sahlgrenska Academy, Go¨teborg University, Kungsgatan 12, SE-411 19 Go¨teborg, Sweden
A R T I C L E I N F O
A B S T R A C T
Article history: Received 30 June 2009 Received in revised form 21 July 2009 Accepted 22 July 2009
Many studies have shown that children with autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) have had early indicators of language delay. The aim of the present study was to examine the cognitive profile of school age children referred to a specialist clinic for ASD, ADHD, or both, and relate this profile specifically to the age at which these children were first flagged up (or not) as suspected from language delay during the preschool years. Forty clinic children with ASD, ADHD, or the combination of the two (without clinical suspicion of learning disability) were assessed cognitively and as regards language development and language function at a mean age of 7.3 years. They were contrasted with a group of 21 children from the community who had been flagged at 2.5 years as suspected of language delay, and who had been followed up neuropsyhiatrically/neuropsychologically and in respect of language at a mean age of 7.9 years. Mean WISC-III full scale IQ was lower than population norms (in spite of the exclusion in both samples of cases with obvious learning disability) and similar across diagnostic groups (ASD and ADHD), and across settings (clinic and community). WISC-III Kaufman factor profiles separated the diagnostic groups as regards Perceptual Organisation. Early concern about language delay was a strong predictor of lower IQ and of distinguishing between ‘‘pure’’ cases of ASD and ADHD. School age clinic children who present with ASD and ADHD have a similar cognitive and early language development profile as do those children from the community, followed prospectively, who present with a suspicion of early preschool
Keywords: Autism ADHD Cognitive profile Language delay
* Corresponding author. E-mail addresses: [email protected], [email protected] (B.S. Hagberg). 0891-4222/$ – see front matter ß 2009 Published by Elsevier Ltd. doi:10.1016/j.ridd.2009.07.012
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language delay and are shown at school age to suffer from ASD or ADHD. Concern about early language delay in the preschool age should prompt assessments (psychiatric and cognitively) for ASD and ADHD in a multidisciplinary setting much more often than is currently the case. In many cases early language delay, even in the absence of clear learning disability should be taken as a signal that – regardless of specific diagnosis – intellectual functioning might be in the low average range. ß 2009 Published by Elsevier Ltd.
1. Introduction Language delay (LD) and language impairments are common in autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) (Beitchman et al., 2001; Cantwell & Baker, 1991; Fernell, Norrelgren, Bozkurt, Hellberg, & Lo¨ving, 2002; Miniscalco, Nygren, Hagberg, Kadesjo¨, & Gillberg, 2006; Rasmussen, Gillberg, Waldenstro¨m, & Svensson, 1983; Snowling, Bishop, & Stothard, 2006). The prevalence rates of ASD and ADHD are about 1 and 5%, respectively (Kadesjo¨ & Gillberg, 1999), i.e. they are common disorders, and are accepted as major public health problems. The corresponding prevalence figures of LD from different international studies range from 1 to 15% as a whole (Law et al., 2000). In Sweden the prevalence rate of diagnosed LD is around 6% (Miniscalco, 2003). Several longitudinal studies – both Swedish and international – of children with LD indicate that these children have an increased risk of literacy, educational and behavioural difficulties (ContiRamsden, Simkin, & Botting, 2006; Miniscalco et al., 2006; Snowling et al., 2006). Lundervold, Posserud, Sorensen, and Gillberg (2008) have shown that children with language problems reported by teachers have significantly lower scores than children without such problems on tests of intellectual functioning. Thus, in addition LD may also be associated with a more general cognitive impairment. Other follow up studies have shown that, even when language skills improve, these children remain at risk for other difficulties such as behavioural and attentional problems (Lundervold, Heimann, & Manger, 2008; Mawhood, Howlin & Rutter, 2000) and cognitive and academic delays (Silva, Williams & McGee, 1987). Other studies (Mawhood et al., 2000) have shown that nonautistic children with developmental language disorder show non-language impairment that is similar to those found in autism. One study (Silva et al., 1987) comparing children with developmental LD with a group of children with autism found linguistic similarities in both groups of children, but the language-related deficits were more profound in the autism group. Further more studies have found similar results. Lincoln, Courchesue, Kilman, Elmasian, and Allen (1988), found that high-functioning children with autism showed more severe language and cognitive abnormalities from those found in children diagnosed as having receptive developmental language disorder. In contrast, other studies have shown some different results. Paul and Cohen (1984), reported in a study of language-disordered children followed up into adolescence, that at least half showed symptoms characteristic of autism. In Sweden children with LD are identified by screening programs run at Child Health Centres/well baby clinics at 2.5, 4 and 5.5 years (Miniscalco Mattsson, Ma˚rild, & Pehrsson, 2001; Westerlund, 1994). At 2.5 years of age the screening focuses on the child’s ability to communicate and to produce and understand single and multiword utterances, and at 4 years of age it focuses on expressive speech and language (mainly phonology and grammar). One Swedish study (Miniscalco, Westerlund & Lohmander, 2005) has shown that children who failed the 2.5-year screening had persistent language problems at 6 years of age, which shows the importance of screening programme and early intervention. However very little attention is paid to other aspects of language, such as pragmatics (language use) and semantics (language content), which have strong connections with the social and cognitive functions of language (Tager-Flusberg, 1995; Bishop, 1997). Lack of communicative competence and pervasive pragmatic deficits are core symptoms in children with ASD. These children are also often initially referred for examination because of delayed language development (Dahlgren & Gillberg, 1989). Several longitudinal and cross-sectional studies have addressed the co-existence between LD and neuropsychiatric disorders (Cantwell & Baker, 1991; Conti-Ramsden et al., 2006; Fernell et al., 2002;
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Rasmussen et al., 1983) in spite of these well established links between ASD and ADHD on the one hand and LD on the other little is known about the cognitive ‘‘profile’’ in children affected. We wanted to determine whether children who came to clinics for ASD/ADHD at school age are cognitively similar to those who have been identified as having LD before age 3 years. We know that there is a high rate of ASD/ADHD at school age in the latter group, but is the ASD/ADHD ‘‘of the same’’ type as in the former? Were that to be the case, then it would appear to be even more strongly indicated to always follow up young children with LD with a view to discover ASD/ADHD and intervening as early as possible. In the present study we examined the cognitive profiles of school age children referred to specialist clinics for ASD, ADHD, or both, and related these profiles specifically to the age at which the children were first flagged up (or not) as suspected from LD during the preschool years. We also compared their profiles with those of children from the community who had raised concern about language development at age 2.5 years and who had been followed up and shown to have very high rates of ASD and ADHD at school age (Miniscalco et al., 2006). 2. Aims The present study specifically aims to determine (1) whether clinic cases of children with ASD, ADHD, or both, had been identified by the language screening surveillance programmes performed at child well baby clinics at different ages during the preschool period, (2) the relationship, if any, between age at preschool concern about language delay on the one hand and presence and type of cognitive profile (and neuropsychiatric diagnosis) at early school age (6–9 years) on the other, and (3) whether or not this group of psychiatric clinic referred school age children with ASD/ADHD differed cognitively from non-referred community children with preschool concern about language delay (many of whom were later diagnosed with ASD/ADHD in the course of a longitudinal follow-up study at school age). 3. Methods 3.1. Participants 3.1.1. Psychiatric clinic cases of ASD, ADHD or both (Clinic ASD/ADHD) Forty psychiatric clinic attenders (36 boys, 4 girls) with ASD and/or ADHD were included in the study. They were recruited in the following way. First, all cases – 109 children (88 boys, 21 girls) – of 6– 9-year-old children born in 1995–1996 referred for assessment of suspected ASD or ADHD (or both) to the Child Neuropsychiatry Clinic (CNC) at Queen Silvia’s Children’s University Hospital, Go¨teborg during 1 year (July 1, 2003 through June 30, 2004) were reviewed for possible inclusion in the present study. The criteria for exclusion were: (1) diagnosed or strongly clinically suspected learning disability (IQ < 70), (2) participation in another ongoing study at the clinic, (3) established genetic disorder such as Angelman’s syndrome, 22q11-deletion syndrome or tuberous sclerosis, and (4) children not having Swedish as their first language. After this exclusion process, there remained 46 cases in the cohort. All these children were seen and systematically examined in accordance with the research protocol as detailed below. Six of the children were found not to meet clinical diagnostic criteria for ASD or ADHD – but were diagnosed as suffering from speech-language impairment ‘‘only’’ (n = 1), cerebellar ataxia ‘‘only’’ (n = 1) or learning disability ‘‘only’’ (n = 4). These non-ADHD/non-ASD cases were not included in the present study. Thus, the experimental group comprised 36 boys, and 4 girls, whose mean age at neuropsychological evaluation was 7.3 (range 6.4–9.9) years. The very low rate of girls in this study group is partly explained by the lower male: female ratio in groups (1)–(3) under ‘‘exclusion’’ above. It is our contention that the 40 cases included are representative of non-syndromic, nonlearning-disabled school age children with ASD and/or ADHD (for diagnostic methods, see below). 3.1.2. Community cases with suspected LD at 30 months followed up at school age (Community LD) For some comparisons, a group of representative community children followed prospectively because of preschool concern about early LD (age 2.5 years) and worked up with a view to diagnosing
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or excluding ASD or ADHD at school age (7–8 years) – as part of a planned longitudinal study – was included. Exactly the same preschool screening and school age in-depth assessments as in the Clinic ASD/ADHD group were performed in this Community LD group. This group comprised 21 individuals (17 boys, 4 girls). Their mean age at cognitive evaluation was 7.9 (range 7.3–9.1) years. Thirteen of these 21 children (12 boys, 1 girl) (mean age 7.1, range 7.4–9.1) had been diagnosed as suffering from ASD, ADHD or both at the time of the follow-up at 7–8 years. We have argued elsewhere (Miniscalco et al., 2006) that this group is representative of children in the general population who raise concern because of suspected LD at 30 months. 3.2. Methods used All 61 children (40 clinic, 21 community) were given in-depth neuropsychiatric examinations focusing on ASD (including autistic disorder/childhood autism/A, atypical autism/pervasive developmental disorder (PDD) not otherwise specified/AA, and Asperger syndrome/AS), and ADHD. The Gillberg & Gillberg criteria were used for diagnosing Asperger syndrome, DISCO interviews were made to diagnose autistic disorder/childhood autism. The criteria of the DSM-IV were checked for ADHD. All children examined were seen by (i) one of three doctors, (ii) one child neuropsychologist (BH), and (iii) one speech-language pathologist (SLP) (CM), all of whom had many years of clinical and research experience in the field. The three categories of professionals examined each child within a period of 2 weeks, and all test items were presented in the same order. The examiners were aware of that the children had been referred for assessment of suspected ASD or ADHD (or both) to the Child Neuropsychiatry Clinic (CNC) at Queen Silvia’s Children’s University Hospital, Go¨teborg. In this study only cognitive profiles, earlier problems with language development and the presence of neuropsychiatric diagnoses will be reported. The cognitive assessment consisted of the WISC-III (Wechsler, 1999) – yielding full scale IQ (FSIQ), verbal IQ (VIQ), performance IQ (PIQ), and four factors according to Kaufman: Verbal Comprehension (VC), Perceptual Organisation (PO), Freedom from Distractibility (FD) and Processing Speed (PS). A history was taken (and medical and other records reviewed whenever indicated) regarding previous contacts with SLP services, which, for preschool Swedish children are systematically organised, and any child raising suspicion of clinically significant speech delay at the well baby clinic (which reaches almost 100% of all preschool children, Magnusson, 1997, is referred to such services for assessment (for a detailed description of these assessment procedures, see Miniscalco et al., 2006)). Finally, all children were physically and psychiatrically examined by a specialist doctor, who also performed a brief motor examination, using the items described by Kadesjo¨ and Gillberg (1999). The criteria of the DSM-IV (American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, 1994) were checked for ASD (‘‘PDD’’) and ADHD. The Diagnostic Interview for Social and COmmunication disorders (DISCO-10) (Wing, Leekham, Libby, Gould, & Larcombe, 2002) was used for all children raising any suspicion of suffering from ASD. Five To Fifteen (FTF) parent and teacher questionnaires (Kadesjo¨ et al., 2004) were completed in most cases. The results are expressed as mean SD. Differences between groups were analyzed using Kruskal– Wallis and Dunn’s Multiple Comparison Test or the Mann–Whitney test. The Ethics Committee of the Medical Faculty, Go¨teborg, approved the study, and the parents provided written informed consent. 4. Results 4.1. ADHD/ASD diagnosis in clinical children in relation to early concern about language problems The rate of preschool SLP contact was high among the 40 children in the Clinic ASD/ADHD group (Table 1). In all, 24/40 (60%) – 7/10 (70%) of those with ASD only, 15/21 (71%) of those with ASD + ADHD, and 2/9 (22%) of those with ADHD only had been in contact with SLP services during the preschool years. There was a significant difference between children who had ASD or ASD + ADHD compared to ADHD only (p = 0.0175). It was only 3/15 (20%) in the group with no SLP contact who had ASD and none with ‘‘pure’’ Asperger syndrome.
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Table 1 Age at SLP contact and neuropsychiatric diagnosis in the Clinic ASD/ADHD group (n = 40). SLP contact at age (years)
Male (female) ASD (n = 10)
ASD/ADHD (n = 21)
ADHD (n = 9)
Total (n = 40)
2.5 4.0 5.5
5 (0) 1 (0) 1 (0)
6 (1) 4 (2) 2 (0)
1 (0) 0 (0) 1 (0)
12 (1) 5 (2) 4 (0)
No SLP contact
3 (0)
5 (1)
7 (0)
15 (1)
Contact with the SLP service tended to be earlier in the ASD only and ASD/ADHD group (5/10 (50%) and 7/21 (33%) respectively at age 2.5 years) than in the ADHD only group (1/9 (11%) at age 2.5 years (n.s.)). 4.2. Cognitive profiles in relation to early concern about language problems All 16 clinic children without early contact with SLP services had FSIQ within the normal (85–115) range (mean value 93.1, SD 15.0) (Table 2). On the VC factor (Verbal Comprehension) their mean IQ was 100.3 SD 13.1. Overall, those 60% of the sample who had been in contact with SLP services had lower FSIQ (mean value 83.3) than did those 40% (mean value 93.1) who had not had such contact during the preschool years (n.s.). Thirteen of the 40 children had been referred to a SLP for a suspicion of language problems at 2.5 years of age and scored low on FSIQ and VC compared to those who had not been referred to a SLP at 2.5 years of age. Seven children had been referred at 4 years of age and their FSIQ was 85.2 (SD 16.5) and they also scored rather low on VC. The four children who had been referred to the SLP at 5.5 years of age had the lowest FSIQ of all. Mean PIQ was within normal limits (85–115) except for the four children referred at 5.5 years of age (73.6 SD 11.2). Mean VIQ and mean VC was within these normal limits (but in the lower range) for the children who had had SLP contact. Mean FD (Freedom from Distractibility) was significant lower for children referred at 2.5 years of age compared to the children who had had no SLP contact. FD was low even for children referred at 4 and 5.5 years of age, however it was not significant compared to children without SLP contact. 4.3. Diagnosis of ASD and/or ADHD in relation to cognitive profiles Data concerning cognitive profiles in relation to ASD and/or ADHD are presented in Table 3. The mean scores were within the normal range (85–115) in all groups on WISC-III, FSIQ, VIQ, and PIQ.
Table 2 WISC-III cognitive profiles and Kaufman 4-factor construct in 40 clinic children with ASD/ADHD broken down according to age at concern about early language delay. SLP contact (n)
Mean (SD) FSIQ
No (n = 16) 2.5–3 years (n = 13) 4 years (n = 7) 5.5 years (n = 4a)
93.1 89.1 85.2 75.7
VIQ (15.0) (10.9) (16.5) (7.3)
96.9 85.9 84.8 84.6
PIQ (14.8) (11.8) (13.1) (8.5)
90.3 95.6 89.2 73.6
(15.9) (18.2) (19.2) (11.2)
VC
PO
100.3 (13.1) 88.6* (12.5) 88.5* (12.4) 87.0 (9.6)
94.8 100.4 87.1 79.0
(18.5) (18.8) (22.2) (10.5)
FD
PS
88.8 (17.6) 73.3* (14.2) 76.5 (16.8) 83.3 (9.2)
90.0 85.2 97.2 67.0
(14.1) (18.1) (17.8) (3.5)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension, PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. a One child had not been assessed with WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales. * p< .05 vs no SLP contact cases.
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Table 3 WISC-III cognitive profile in 40 children with ASD, ADHD or the combination of both. Diagnosis
ASD (n = 10a) ASD/ADHD (n = 21) ADHD (n = 9)
Mean (SD) FSIQ
VIQ
PIQ
VC
PO
FD
PS
89.5 (14.4) 88.0 (15.4) 89.5 (11.4)
87.6 (11.2) 90.0 (15.2) 93 (14.2)
98.4 (17.7) 88.4 (17.3) 87.8 (17.0)
90.5 (11.0) 94.1 (15.1) 95.1 (12.1)
102.4 (24.3) 91.8 (17.4) 91.0 (17.7)
78.6 (11.1) 78.9 (16.6) 88.3 (21.6)
85.2 (16.2) 88.8 (19.3) 88.6 (12.7)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension. PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. a One child had not been assessed with the WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales. Table 4 Comparison of cognitive profiles in 40 Clinic ASD/ADHD cases and 21 Community LD cases. Group
Clinic ASD/ADHD (n = 40a) Community LD (n = 21)
Mean (SD) FSIQ
VIQ
PIQ
VC
PO
FD
PS
88.7 (14.0) 88.8 (14.5)
90.1 (13.9) 89.0 (12.3)
90.6 (17.4) 91.3 (17.6)
93.5 (13.4) 93.0 (11.8)
94.1 (19.2) 94.0 (16.1)
81.1 (16.9) 77.0 (15.8)
87.9 (16.9) 86.5 (18.0)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension, PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. No significant differences. a One child had not been assessed with the WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales.
The children with ASD had a mean score 102.4 on PO (Perceptual Organisation) compared to the group with ADHD 91.0 (p = 0.12). Their mean score on PIQ was 98.4 compared to ASD/ADHD 88.4 and ADHD 87.8 (n.s.). The ASD and ASD/ADHD groups had very poor results on FD (78.6 and 78.9, respectively). The children with ADHD also scored low (88.3 SD 21.6) on this factor but not as low as the ASD and ASD/ ADHD groups (p = 0.49). 4.4. Clinic and community cases with ADHD/ASD contrasted The 40 clinic children were first compared with all 21 community children as regards cognitive profiles (Table 4). No differences were found across the two groups. Thirteen children in the Clinic ASD/ ADHD group had been referred to SLP services at age 2.5 years. They were compared with those 13 school age children in the Community LD group who had been referred to SLP services at the same age and who (according to prospective analysis) had been diagnosed with ADHD/ASD at school age (Fig. 1). These two
Fig. 1. Cognitive profiles using WISC-III and Kaufman 4-factor in 13 Clinic children with ASD/ADHD (CNC) and 21 children with LD+
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groups had very similar overall profiles with FSIQ = PIQ= VIQ in the 80–100 range but with very low results on FD (73.3 and 68.0, respectively). 5. Discussion The present study showed that 60% of the clinic children with ASD/ADHD and ADHD had been in contact with SLP services during their preschool years which confirm earlier studies (Dahlgren & Gillberg, 1989). Overall, those 60% who had been in contact with SLP had lower FSIQ than did those 40% who had not had such contact during the preschool period. All 16 clinic children without early contact with SLP services had FSIQ within the average (85–115) range. The clinic children who had been referred to SLP had significantly lower results on VC than the children without early contact with SLP. Clinic children who had been referred to SLP services at 2.5 years had the same neuropsychological profile as community diagnosed with ASD/ADHD. They all showed very low results on FD. Children with ADHD and/or ASD often have similar weaknesses on FD and PS (Mayes & Calhoun, 2007) and this seems to hold true even for children initially referred due to language problems because both the CNC and LD+ group had their troughs on FD and PS. In 1987 Bishop and Edmundson argued for regarding language delay as a signal of a general neurodevelopmental lag that affects a variety of developmental areas, and not as a specific isolated phenomenon. The community group of the present study is considered to be representative of children in the community (Miniscalco et al., 2006). The clinic children are considered to be representative of children with suspected neuropsychiatric disorders – usually ASD and/or ADHD – referred at 7–8 years of age. We excluded children with obvious learning disabilities, i.e. IQ < 70, genetic disorders, participating in another ongoing study and children not having Swedish as their first language. Once identified as children with LD they tend to get SLP services only, and in cases of often ‘‘recovery’’ they get no further SLP contact but end up in the early school years at the CNC with behavioural problems and/or learning disabilities. Our findings indicate that the two groups of children (clinic and community) are extremely similar. The co-morbidity of LD with learning disability is well known. Lundervold, Posserud, et al. (2008) have recently documented the overlap in a large Norwegian population study where teacher report of ‘‘language problems’’ in the child usually indicated significantly lower IQ. Studies have also shown the high prevalence of neuropsychiatric and/or neurodevelopmental diagnoses in children with LD at early school age follow-up (Bax and Whitmore, 1987; Conti-Ramsden et al., 2006; Miniscalco et al., 2006). In summary LD is not usually an isolated phenomena, many studies have shown that language impairment and neuropsychiatric or neurodevelopmental disorder in the child appear at the same time (Fernell et al., 2002; Miniscalco et al., 2006; Snowling, Adams, Bishop, & Stothard, 2001). This now well documented fact should lead to better awareness about the need for early diagnosis and intervention of neuropsychiatric problems that may eventually become the functionally most impairing symptoms in children with LD. 6. Limitations The major limitation is the small study group, which calls for caution in interpreting the results. The study was performed during a limited period of time and included only one age group. The lack of a blindly examined control group is also a potential limitation. 7. Conclusion School age clinic children who present with ASD and ADHD have a similar neuropsychological and early language development profile as do those children from the community, followed prospectively, who present with a suspicion of early preschool language delay and are shown at school age to suffer from ASD or ADHD. Concern about early language delay in the preschool age should prompt assessments (psychiatric and cognitive) for ASD and ADHD in a multidisciplinary setting much more
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International Journal of Language and Communication Disorder, 36, 173–183. Snowling, M. J., Bishop, D. V., & Stothard, S. E. (2006). Psychosocial outcomes at 15 years of children with a preschool history of speech-language impairment. Journal of Child Psychology and Psychiatry, 47, 759–765. Tager-Flusberg, H. (1995). Once upon a rabbit: Stories narrated by autistic children. British Journal of Developmental Psychology, 13, 45–59. Wechsler, D. (1999). Wechsler Intelligence Scale for Children – Third edition. WISC-III. Swedish Manual. Stockholm: Psykologifo¨rlaget. Westerlund, M. (1994). Children with Speech and Language deviations. A prospective longitudinal epidemiological study of total age cohort of children living in Uppsala at 4, 7 and 9 years of age. In Swedish. Doctorial Thesis. Uppsala University, Uppsala, Sweden. Wing, L., Leekham, S. R., Libby, S. J., Gould, J., & Larcombe, M. (2002). The diagnostic interview for social and communication disorders: background, inter-rater reliability and clinical use. Journal of Child Psychology and Psychiatry, 43, 307–325.
Contents lists available at ScienceDirect
Research in Developmental Disabilities
Clinic attenders with autism or attention-deficit/ hyperactivity disorder: cognitive profile at school age and its relationship to preschool indicators of language delay Bibbi S. Hagberg *, Carmela Miniscalco, Christopher Gillberg Department of Child and Adolescent Psychiatry, Sahlgrenska Academy, Go¨teborg University, Kungsgatan 12, SE-411 19 Go¨teborg, Sweden
A R T I C L E I N F O
A B S T R A C T
Article history: Received 30 June 2009 Received in revised form 21 July 2009 Accepted 22 July 2009
Many studies have shown that children with autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) have had early indicators of language delay. The aim of the present study was to examine the cognitive profile of school age children referred to a specialist clinic for ASD, ADHD, or both, and relate this profile specifically to the age at which these children were first flagged up (or not) as suspected from language delay during the preschool years. Forty clinic children with ASD, ADHD, or the combination of the two (without clinical suspicion of learning disability) were assessed cognitively and as regards language development and language function at a mean age of 7.3 years. They were contrasted with a group of 21 children from the community who had been flagged at 2.5 years as suspected of language delay, and who had been followed up neuropsyhiatrically/neuropsychologically and in respect of language at a mean age of 7.9 years. Mean WISC-III full scale IQ was lower than population norms (in spite of the exclusion in both samples of cases with obvious learning disability) and similar across diagnostic groups (ASD and ADHD), and across settings (clinic and community). WISC-III Kaufman factor profiles separated the diagnostic groups as regards Perceptual Organisation. Early concern about language delay was a strong predictor of lower IQ and of distinguishing between ‘‘pure’’ cases of ASD and ADHD. School age clinic children who present with ASD and ADHD have a similar cognitive and early language development profile as do those children from the community, followed prospectively, who present with a suspicion of early preschool
Keywords: Autism ADHD Cognitive profile Language delay
* Corresponding author. E-mail addresses: [email protected], [email protected] (B.S. Hagberg). 0891-4222/$ – see front matter ß 2009 Published by Elsevier Ltd. doi:10.1016/j.ridd.2009.07.012
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language delay and are shown at school age to suffer from ASD or ADHD. Concern about early language delay in the preschool age should prompt assessments (psychiatric and cognitively) for ASD and ADHD in a multidisciplinary setting much more often than is currently the case. In many cases early language delay, even in the absence of clear learning disability should be taken as a signal that – regardless of specific diagnosis – intellectual functioning might be in the low average range. ß 2009 Published by Elsevier Ltd.
1. Introduction Language delay (LD) and language impairments are common in autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) (Beitchman et al., 2001; Cantwell & Baker, 1991; Fernell, Norrelgren, Bozkurt, Hellberg, & Lo¨ving, 2002; Miniscalco, Nygren, Hagberg, Kadesjo¨, & Gillberg, 2006; Rasmussen, Gillberg, Waldenstro¨m, & Svensson, 1983; Snowling, Bishop, & Stothard, 2006). The prevalence rates of ASD and ADHD are about 1 and 5%, respectively (Kadesjo¨ & Gillberg, 1999), i.e. they are common disorders, and are accepted as major public health problems. The corresponding prevalence figures of LD from different international studies range from 1 to 15% as a whole (Law et al., 2000). In Sweden the prevalence rate of diagnosed LD is around 6% (Miniscalco, 2003). Several longitudinal studies – both Swedish and international – of children with LD indicate that these children have an increased risk of literacy, educational and behavioural difficulties (ContiRamsden, Simkin, & Botting, 2006; Miniscalco et al., 2006; Snowling et al., 2006). Lundervold, Posserud, Sorensen, and Gillberg (2008) have shown that children with language problems reported by teachers have significantly lower scores than children without such problems on tests of intellectual functioning. Thus, in addition LD may also be associated with a more general cognitive impairment. Other follow up studies have shown that, even when language skills improve, these children remain at risk for other difficulties such as behavioural and attentional problems (Lundervold, Heimann, & Manger, 2008; Mawhood, Howlin & Rutter, 2000) and cognitive and academic delays (Silva, Williams & McGee, 1987). Other studies (Mawhood et al., 2000) have shown that nonautistic children with developmental language disorder show non-language impairment that is similar to those found in autism. One study (Silva et al., 1987) comparing children with developmental LD with a group of children with autism found linguistic similarities in both groups of children, but the language-related deficits were more profound in the autism group. Further more studies have found similar results. Lincoln, Courchesue, Kilman, Elmasian, and Allen (1988), found that high-functioning children with autism showed more severe language and cognitive abnormalities from those found in children diagnosed as having receptive developmental language disorder. In contrast, other studies have shown some different results. Paul and Cohen (1984), reported in a study of language-disordered children followed up into adolescence, that at least half showed symptoms characteristic of autism. In Sweden children with LD are identified by screening programs run at Child Health Centres/well baby clinics at 2.5, 4 and 5.5 years (Miniscalco Mattsson, Ma˚rild, & Pehrsson, 2001; Westerlund, 1994). At 2.5 years of age the screening focuses on the child’s ability to communicate and to produce and understand single and multiword utterances, and at 4 years of age it focuses on expressive speech and language (mainly phonology and grammar). One Swedish study (Miniscalco, Westerlund & Lohmander, 2005) has shown that children who failed the 2.5-year screening had persistent language problems at 6 years of age, which shows the importance of screening programme and early intervention. However very little attention is paid to other aspects of language, such as pragmatics (language use) and semantics (language content), which have strong connections with the social and cognitive functions of language (Tager-Flusberg, 1995; Bishop, 1997). Lack of communicative competence and pervasive pragmatic deficits are core symptoms in children with ASD. These children are also often initially referred for examination because of delayed language development (Dahlgren & Gillberg, 1989). Several longitudinal and cross-sectional studies have addressed the co-existence between LD and neuropsychiatric disorders (Cantwell & Baker, 1991; Conti-Ramsden et al., 2006; Fernell et al., 2002;
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Rasmussen et al., 1983) in spite of these well established links between ASD and ADHD on the one hand and LD on the other little is known about the cognitive ‘‘profile’’ in children affected. We wanted to determine whether children who came to clinics for ASD/ADHD at school age are cognitively similar to those who have been identified as having LD before age 3 years. We know that there is a high rate of ASD/ADHD at school age in the latter group, but is the ASD/ADHD ‘‘of the same’’ type as in the former? Were that to be the case, then it would appear to be even more strongly indicated to always follow up young children with LD with a view to discover ASD/ADHD and intervening as early as possible. In the present study we examined the cognitive profiles of school age children referred to specialist clinics for ASD, ADHD, or both, and related these profiles specifically to the age at which the children were first flagged up (or not) as suspected from LD during the preschool years. We also compared their profiles with those of children from the community who had raised concern about language development at age 2.5 years and who had been followed up and shown to have very high rates of ASD and ADHD at school age (Miniscalco et al., 2006). 2. Aims The present study specifically aims to determine (1) whether clinic cases of children with ASD, ADHD, or both, had been identified by the language screening surveillance programmes performed at child well baby clinics at different ages during the preschool period, (2) the relationship, if any, between age at preschool concern about language delay on the one hand and presence and type of cognitive profile (and neuropsychiatric diagnosis) at early school age (6–9 years) on the other, and (3) whether or not this group of psychiatric clinic referred school age children with ASD/ADHD differed cognitively from non-referred community children with preschool concern about language delay (many of whom were later diagnosed with ASD/ADHD in the course of a longitudinal follow-up study at school age). 3. Methods 3.1. Participants 3.1.1. Psychiatric clinic cases of ASD, ADHD or both (Clinic ASD/ADHD) Forty psychiatric clinic attenders (36 boys, 4 girls) with ASD and/or ADHD were included in the study. They were recruited in the following way. First, all cases – 109 children (88 boys, 21 girls) – of 6– 9-year-old children born in 1995–1996 referred for assessment of suspected ASD or ADHD (or both) to the Child Neuropsychiatry Clinic (CNC) at Queen Silvia’s Children’s University Hospital, Go¨teborg during 1 year (July 1, 2003 through June 30, 2004) were reviewed for possible inclusion in the present study. The criteria for exclusion were: (1) diagnosed or strongly clinically suspected learning disability (IQ < 70), (2) participation in another ongoing study at the clinic, (3) established genetic disorder such as Angelman’s syndrome, 22q11-deletion syndrome or tuberous sclerosis, and (4) children not having Swedish as their first language. After this exclusion process, there remained 46 cases in the cohort. All these children were seen and systematically examined in accordance with the research protocol as detailed below. Six of the children were found not to meet clinical diagnostic criteria for ASD or ADHD – but were diagnosed as suffering from speech-language impairment ‘‘only’’ (n = 1), cerebellar ataxia ‘‘only’’ (n = 1) or learning disability ‘‘only’’ (n = 4). These non-ADHD/non-ASD cases were not included in the present study. Thus, the experimental group comprised 36 boys, and 4 girls, whose mean age at neuropsychological evaluation was 7.3 (range 6.4–9.9) years. The very low rate of girls in this study group is partly explained by the lower male: female ratio in groups (1)–(3) under ‘‘exclusion’’ above. It is our contention that the 40 cases included are representative of non-syndromic, nonlearning-disabled school age children with ASD and/or ADHD (for diagnostic methods, see below). 3.1.2. Community cases with suspected LD at 30 months followed up at school age (Community LD) For some comparisons, a group of representative community children followed prospectively because of preschool concern about early LD (age 2.5 years) and worked up with a view to diagnosing
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or excluding ASD or ADHD at school age (7–8 years) – as part of a planned longitudinal study – was included. Exactly the same preschool screening and school age in-depth assessments as in the Clinic ASD/ADHD group were performed in this Community LD group. This group comprised 21 individuals (17 boys, 4 girls). Their mean age at cognitive evaluation was 7.9 (range 7.3–9.1) years. Thirteen of these 21 children (12 boys, 1 girl) (mean age 7.1, range 7.4–9.1) had been diagnosed as suffering from ASD, ADHD or both at the time of the follow-up at 7–8 years. We have argued elsewhere (Miniscalco et al., 2006) that this group is representative of children in the general population who raise concern because of suspected LD at 30 months. 3.2. Methods used All 61 children (40 clinic, 21 community) were given in-depth neuropsychiatric examinations focusing on ASD (including autistic disorder/childhood autism/A, atypical autism/pervasive developmental disorder (PDD) not otherwise specified/AA, and Asperger syndrome/AS), and ADHD. The Gillberg & Gillberg criteria were used for diagnosing Asperger syndrome, DISCO interviews were made to diagnose autistic disorder/childhood autism. The criteria of the DSM-IV were checked for ADHD. All children examined were seen by (i) one of three doctors, (ii) one child neuropsychologist (BH), and (iii) one speech-language pathologist (SLP) (CM), all of whom had many years of clinical and research experience in the field. The three categories of professionals examined each child within a period of 2 weeks, and all test items were presented in the same order. The examiners were aware of that the children had been referred for assessment of suspected ASD or ADHD (or both) to the Child Neuropsychiatry Clinic (CNC) at Queen Silvia’s Children’s University Hospital, Go¨teborg. In this study only cognitive profiles, earlier problems with language development and the presence of neuropsychiatric diagnoses will be reported. The cognitive assessment consisted of the WISC-III (Wechsler, 1999) – yielding full scale IQ (FSIQ), verbal IQ (VIQ), performance IQ (PIQ), and four factors according to Kaufman: Verbal Comprehension (VC), Perceptual Organisation (PO), Freedom from Distractibility (FD) and Processing Speed (PS). A history was taken (and medical and other records reviewed whenever indicated) regarding previous contacts with SLP services, which, for preschool Swedish children are systematically organised, and any child raising suspicion of clinically significant speech delay at the well baby clinic (which reaches almost 100% of all preschool children, Magnusson, 1997, is referred to such services for assessment (for a detailed description of these assessment procedures, see Miniscalco et al., 2006)). Finally, all children were physically and psychiatrically examined by a specialist doctor, who also performed a brief motor examination, using the items described by Kadesjo¨ and Gillberg (1999). The criteria of the DSM-IV (American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, 1994) were checked for ASD (‘‘PDD’’) and ADHD. The Diagnostic Interview for Social and COmmunication disorders (DISCO-10) (Wing, Leekham, Libby, Gould, & Larcombe, 2002) was used for all children raising any suspicion of suffering from ASD. Five To Fifteen (FTF) parent and teacher questionnaires (Kadesjo¨ et al., 2004) were completed in most cases. The results are expressed as mean SD. Differences between groups were analyzed using Kruskal– Wallis and Dunn’s Multiple Comparison Test or the Mann–Whitney test. The Ethics Committee of the Medical Faculty, Go¨teborg, approved the study, and the parents provided written informed consent. 4. Results 4.1. ADHD/ASD diagnosis in clinical children in relation to early concern about language problems The rate of preschool SLP contact was high among the 40 children in the Clinic ASD/ADHD group (Table 1). In all, 24/40 (60%) – 7/10 (70%) of those with ASD only, 15/21 (71%) of those with ASD + ADHD, and 2/9 (22%) of those with ADHD only had been in contact with SLP services during the preschool years. There was a significant difference between children who had ASD or ASD + ADHD compared to ADHD only (p = 0.0175). It was only 3/15 (20%) in the group with no SLP contact who had ASD and none with ‘‘pure’’ Asperger syndrome.
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Table 1 Age at SLP contact and neuropsychiatric diagnosis in the Clinic ASD/ADHD group (n = 40). SLP contact at age (years)
Male (female) ASD (n = 10)
ASD/ADHD (n = 21)
ADHD (n = 9)
Total (n = 40)
2.5 4.0 5.5
5 (0) 1 (0) 1 (0)
6 (1) 4 (2) 2 (0)
1 (0) 0 (0) 1 (0)
12 (1) 5 (2) 4 (0)
No SLP contact
3 (0)
5 (1)
7 (0)
15 (1)
Contact with the SLP service tended to be earlier in the ASD only and ASD/ADHD group (5/10 (50%) and 7/21 (33%) respectively at age 2.5 years) than in the ADHD only group (1/9 (11%) at age 2.5 years (n.s.)). 4.2. Cognitive profiles in relation to early concern about language problems All 16 clinic children without early contact with SLP services had FSIQ within the normal (85–115) range (mean value 93.1, SD 15.0) (Table 2). On the VC factor (Verbal Comprehension) their mean IQ was 100.3 SD 13.1. Overall, those 60% of the sample who had been in contact with SLP services had lower FSIQ (mean value 83.3) than did those 40% (mean value 93.1) who had not had such contact during the preschool years (n.s.). Thirteen of the 40 children had been referred to a SLP for a suspicion of language problems at 2.5 years of age and scored low on FSIQ and VC compared to those who had not been referred to a SLP at 2.5 years of age. Seven children had been referred at 4 years of age and their FSIQ was 85.2 (SD 16.5) and they also scored rather low on VC. The four children who had been referred to the SLP at 5.5 years of age had the lowest FSIQ of all. Mean PIQ was within normal limits (85–115) except for the four children referred at 5.5 years of age (73.6 SD 11.2). Mean VIQ and mean VC was within these normal limits (but in the lower range) for the children who had had SLP contact. Mean FD (Freedom from Distractibility) was significant lower for children referred at 2.5 years of age compared to the children who had had no SLP contact. FD was low even for children referred at 4 and 5.5 years of age, however it was not significant compared to children without SLP contact. 4.3. Diagnosis of ASD and/or ADHD in relation to cognitive profiles Data concerning cognitive profiles in relation to ASD and/or ADHD are presented in Table 3. The mean scores were within the normal range (85–115) in all groups on WISC-III, FSIQ, VIQ, and PIQ.
Table 2 WISC-III cognitive profiles and Kaufman 4-factor construct in 40 clinic children with ASD/ADHD broken down according to age at concern about early language delay. SLP contact (n)
Mean (SD) FSIQ
No (n = 16) 2.5–3 years (n = 13) 4 years (n = 7) 5.5 years (n = 4a)
93.1 89.1 85.2 75.7
VIQ (15.0) (10.9) (16.5) (7.3)
96.9 85.9 84.8 84.6
PIQ (14.8) (11.8) (13.1) (8.5)
90.3 95.6 89.2 73.6
(15.9) (18.2) (19.2) (11.2)
VC
PO
100.3 (13.1) 88.6* (12.5) 88.5* (12.4) 87.0 (9.6)
94.8 100.4 87.1 79.0
(18.5) (18.8) (22.2) (10.5)
FD
PS
88.8 (17.6) 73.3* (14.2) 76.5 (16.8) 83.3 (9.2)
90.0 85.2 97.2 67.0
(14.1) (18.1) (17.8) (3.5)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension, PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. a One child had not been assessed with WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales. * p< .05 vs no SLP contact cases.
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Table 3 WISC-III cognitive profile in 40 children with ASD, ADHD or the combination of both. Diagnosis
ASD (n = 10a) ASD/ADHD (n = 21) ADHD (n = 9)
Mean (SD) FSIQ
VIQ
PIQ
VC
PO
FD
PS
89.5 (14.4) 88.0 (15.4) 89.5 (11.4)
87.6 (11.2) 90.0 (15.2) 93 (14.2)
98.4 (17.7) 88.4 (17.3) 87.8 (17.0)
90.5 (11.0) 94.1 (15.1) 95.1 (12.1)
102.4 (24.3) 91.8 (17.4) 91.0 (17.7)
78.6 (11.1) 78.9 (16.6) 88.3 (21.6)
85.2 (16.2) 88.8 (19.3) 88.6 (12.7)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension. PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. a One child had not been assessed with the WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales. Table 4 Comparison of cognitive profiles in 40 Clinic ASD/ADHD cases and 21 Community LD cases. Group
Clinic ASD/ADHD (n = 40a) Community LD (n = 21)
Mean (SD) FSIQ
VIQ
PIQ
VC
PO
FD
PS
88.7 (14.0) 88.8 (14.5)
90.1 (13.9) 89.0 (12.3)
90.6 (17.4) 91.3 (17.6)
93.5 (13.4) 93.0 (11.8)
94.1 (19.2) 94.0 (16.1)
81.1 (16.9) 77.0 (15.8)
87.9 (16.9) 86.5 (18.0)
Note. FSIQ = full scale IQ, VIQ = verbal IQ, PIQ = performance IQ, VC = Verbal Comprehension, PO = Perceptual Organisation, FD = Freedom from Distractibility, PS = Processing Speed. No significant differences. a One child had not been assessed with the WISC-III due to intellectual difficulties. FSIQ was assessed with Griffith Developmental Scales.
The children with ASD had a mean score 102.4 on PO (Perceptual Organisation) compared to the group with ADHD 91.0 (p = 0.12). Their mean score on PIQ was 98.4 compared to ASD/ADHD 88.4 and ADHD 87.8 (n.s.). The ASD and ASD/ADHD groups had very poor results on FD (78.6 and 78.9, respectively). The children with ADHD also scored low (88.3 SD 21.6) on this factor but not as low as the ASD and ASD/ ADHD groups (p = 0.49). 4.4. Clinic and community cases with ADHD/ASD contrasted The 40 clinic children were first compared with all 21 community children as regards cognitive profiles (Table 4). No differences were found across the two groups. Thirteen children in the Clinic ASD/ ADHD group had been referred to SLP services at age 2.5 years. They were compared with those 13 school age children in the Community LD group who had been referred to SLP services at the same age and who (according to prospective analysis) had been diagnosed with ADHD/ASD at school age (Fig. 1). These two
Fig. 1. Cognitive profiles using WISC-III and Kaufman 4-factor in 13 Clinic children with ASD/ADHD (CNC) and 21 children with LD+
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groups had very similar overall profiles with FSIQ = PIQ= VIQ in the 80–100 range but with very low results on FD (73.3 and 68.0, respectively). 5. Discussion The present study showed that 60% of the clinic children with ASD/ADHD and ADHD had been in contact with SLP services during their preschool years which confirm earlier studies (Dahlgren & Gillberg, 1989). Overall, those 60% who had been in contact with SLP had lower FSIQ than did those 40% who had not had such contact during the preschool period. All 16 clinic children without early contact with SLP services had FSIQ within the average (85–115) range. The clinic children who had been referred to SLP had significantly lower results on VC than the children without early contact with SLP. Clinic children who had been referred to SLP services at 2.5 years had the same neuropsychological profile as community diagnosed with ASD/ADHD. They all showed very low results on FD. Children with ADHD and/or ASD often have similar weaknesses on FD and PS (Mayes & Calhoun, 2007) and this seems to hold true even for children initially referred due to language problems because both the CNC and LD+ group had their troughs on FD and PS. In 1987 Bishop and Edmundson argued for regarding language delay as a signal of a general neurodevelopmental lag that affects a variety of developmental areas, and not as a specific isolated phenomenon. The community group of the present study is considered to be representative of children in the community (Miniscalco et al., 2006). The clinic children are considered to be representative of children with suspected neuropsychiatric disorders – usually ASD and/or ADHD – referred at 7–8 years of age. We excluded children with obvious learning disabilities, i.e. IQ < 70, genetic disorders, participating in another ongoing study and children not having Swedish as their first language. Once identified as children with LD they tend to get SLP services only, and in cases of often ‘‘recovery’’ they get no further SLP contact but end up in the early school years at the CNC with behavioural problems and/or learning disabilities. Our findings indicate that the two groups of children (clinic and community) are extremely similar. The co-morbidity of LD with learning disability is well known. Lundervold, Posserud, et al. (2008) have recently documented the overlap in a large Norwegian population study where teacher report of ‘‘language problems’’ in the child usually indicated significantly lower IQ. Studies have also shown the high prevalence of neuropsychiatric and/or neurodevelopmental diagnoses in children with LD at early school age follow-up (Bax and Whitmore, 1987; Conti-Ramsden et al., 2006; Miniscalco et al., 2006). In summary LD is not usually an isolated phenomena, many studies have shown that language impairment and neuropsychiatric or neurodevelopmental disorder in the child appear at the same time (Fernell et al., 2002; Miniscalco et al., 2006; Snowling, Adams, Bishop, & Stothard, 2001). This now well documented fact should lead to better awareness about the need for early diagnosis and intervention of neuropsychiatric problems that may eventually become the functionally most impairing symptoms in children with LD. 6. Limitations The major limitation is the small study group, which calls for caution in interpreting the results. The study was performed during a limited period of time and included only one age group. The lack of a blindly examined control group is also a potential limitation. 7. Conclusion School age clinic children who present with ASD and ADHD have a similar neuropsychological and early language development profile as do those children from the community, followed prospectively, who present with a suspicion of early preschool language delay and are shown at school age to suffer from ASD or ADHD. Concern about early language delay in the preschool age should prompt assessments (psychiatric and cognitive) for ASD and ADHD in a multidisciplinary setting much more
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