Are Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder Different Manifestations of One Overarching Disorder? Cognitive and Symptom Evidence From a Clinical and Population-Based Sample
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FIGURE 1
Class scores on the Social Communication Questionnaire (SCQ) (left) and the Conners' Parent Rating Scale (CPRS) (middle and right) subscales. Note: A higher mean factor sum score indicated that children in that class lacked more competencies or showed more problems on the specific domain. ASD = subscales reflecting autism spectrum disorder (ASD) symptoms; ADHD = subscales reflecting attention-deficit/hyperactivity disorder (ADHD) symptoms.
FIGURE 2
Differences between the classes on measures of baseline speed, the identification of facial emotions, inhibition, cognitive flexibility, attention, working memory, and detail-focused processing style. Note: (a) Baseline Speed: Group differences presented were based on a mean age of 9.9 years. (b) Identification of Facial Emotions: Group differences presented were based on a mean age of 10.2 years. (c) Motor Inhibition: Group differences presented were based on a mean age of 9.9 years. (d) Cognitive Flexibility: Group differences presented were based on a mean age of 9.9 years. (e) Attention: Group differences presented were based on a mean age of 9.9 years. (f) Working Memory: Group differences presented were based on a mean age of 9.9 years. (g) Detail-focused processing style: Group differences presented were based on a mean age of 9.9 years. Normal refers to the classes with no behavioral problems. Attention-deficit/hyperactivity disorder (ADHD) refers to the class with behavioral problems in ADHD only. ADHD(+ASD) refers to the children who most prominently show severe ADHD symptoms, but who also show autism spectrum disorder (ASD) symptoms. ASD(+ADHD) refers to the class with profound ASD symptoms, but who also show ADHD symptoms. The means are adjusted for the covariate age and error bars represent 1 standard error.
FIGURE 2
Differences between the classes on measures of baseline speed, the identification of facial emotions, inhibition, cognitive flexibility, attention, working memory, and detail-focused processing style. Note: (a) Baseline Speed: Group differences presented were based on a mean age of 9.9 years. (b) Identification of Facial Emotions: Group differences presented were based on a mean age of 10.2 years. (c) Motor Inhibition: Group differences presented were based on a mean age of 9.9 years. (d) Cognitive Flexibility: Group differences presented were based on a mean age of 9.9 years. (e) Attention: Group differences presented were based on a mean age of 9.9 years. (f) Working Memory: Group differences presented were based on a mean age of 9.9 years. (g) Detail-focused processing style: Group differences presented were based on a mean age of 9.9 years. Normal refers to the classes with no behavioral problems. Attention-deficit/hyperactivity disorder (ADHD) refers to the class with behavioral problems in ADHD only. ADHD(+ASD) refers to the children who most prominently show severe ADHD symptoms, but who also show autism spectrum disorder (ASD) symptoms. ASD(+ADHD) refers to the class with profound ASD symptoms, but who also show ADHD symptoms. The means are adjusted for the covariate age and error bars represent 1 standard error.
FIGURE 2
Differences between the classes on measures of baseline speed, the identification of facial emotions, inhibition, cognitive flexibility, attention, working memory, and detail-focused processing style. Note: (a) Baseline Speed: Group differences presented were based on a mean age of 9.9 years. (b) Identification of Facial Emotions: Group differences presented were based on a mean age of 10.2 years. (c) Motor Inhibition: Group differences presented were based on a mean age of 9.9 years. (d) Cognitive Flexibility: Group differences presented were based on a mean age of 9.9 years. (e) Attention: Group differences presented were based on a mean age of 9.9 years. (f) Working Memory: Group differences presented were based on a mean age of 9.9 years. (g) Detail-focused processing style: Group differences presented were based on a mean age of 9.9 years. Normal refers to the classes with no behavioral problems. Attention-deficit/hyperactivity disorder (ADHD) refers to the class with behavioral problems in ADHD only. ADHD(+ASD) refers to the children who most prominently show severe ADHD symptoms, but who also show autism spectrum disorder (ASD) symptoms. ASD(+ADHD) refers to the class with profound ASD symptoms, but who also show ADHD symptoms. The means are adjusted for the covariate age and error bars represent 1 standard error.
FIGURE S1
Examples of stimuli from the cognitive tasks. Note: a. Baseline speed and variability (fixation and signal). b. Facial emotion recognition. c. Inhibition and cognitive flexibility (left compatible and right compatible trials, left incompatible and right incompatible trials). d. Visuo-spatial attention and working memory.
Objective
Autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur. Given the heterogeneity of both disorders, several more homogeneous ASD–ADHD comorbidity subgroups may exist. The current study examined whether such subgroups exist, and whether their overlap or distinctiveness in associated comorbid symptoms and cognitive profiles gives support for a gradient overarching disorder hypothesis or a separate disorders hypothesis.
Method
Latent class analysis was performed on Social Communication Questionnaire (SCQ) and Conners' Parent Rating Scale (CPRS-R:L) data for 644 children and adolescents (5 through 17 years of age). Classes were compared for comorbid symptoms and cognitive profiles of motor speed and variability, executive functioning, attention, emotion recognition, and detail-focused processing style.
Results
Latent class analysis revealed five classes: two without behavioral problems, one with only ADHD behavior, and two with both clinical symptom levels of ASD and ADHD but with one domain more prominent than the other (ADHD[+ASD] and ASD[+ADHD]). In accordance with the gradient overarching disorder hypothesis were the presence of an ADHD class without ASD symptoms and the absence of an ASD class without ADHD symptoms, as well as cognitive functioning of the simple ADHD class being less impaired than that of both comorbid classes. In conflict with this hypothesis was that there was some specificity of cognitive deficits across classes.
Conclusions
The overlapping cognitive deficits may be used to further unravel the shared etiological underpinnings of ASD and ADHD, and the nonoverlapping deficits may indicate why some children develop ADHD despite their enhanced risk for ASD. The two subtypes of children with both ASD and ADHD behavior will most likely benefit from different clinical approaches.
Key Words:
autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), latent class analysis (LCA), heterogeneity, cognitionTo access this article, please choose from the options below
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Supplemental material cited in this article is available online.
This study was partly funded by the Netherlands Organisation for Scientific Research (NWO) by grants 91610024 (N.N.J.R.), 056-13-015 (J.K.B.), and by Neurotechnology Solutions Ltd.
Disclosure: Dr. de Sonneville is the director of Sonares B.V., a company which commercially distributes the Amsterdamse Neuropsychologische Taken (ANT) program. He has served on the advisory board for, on the speakers' bureau for, and as a consultant to Danone, Eli Lilly and Co., Friesland Campina, and Global Pharma Consultancy. Dr. Buitelaar has served on the advisory board for, on the speakers' bureau for, and as a consultant to Janssen-Cilag B.V., Eli Lilly and Co., Bristol-Myers Squibb, Organon/Shering Plough, U.C.B., Shire, Medice, Roche, and Servier. Drs. van der Meer, Oerlemans, van Steijn, Lappenschaar, and Rommelse report no biomedical financial interests or potential conflicts of interest.
