Individuals with ASD Meet Diagnostic Criteria for Co-Occurring Developmental Coordination Disorder

Background: Autism Spectrum Disorder (ASD) and Developmental Coordination Disorder (DCD) are developmental disorders with distinct definitions and diagnostic criteria. DCD is characterized by poor motor proficiency despite age and opportunity for learning. ASD and DCD can now be diagnosed as co-occurring in the same individual (DSM-5; APA, 2013). Systematic assessment for DCD is uncommon in the ASD diagnostic process, despite shared sensorimotor symptoms, and so the rate of co-occurrence (ASD+DCD) remains unknown.

Objectives: We aimed to determine whether individuals with ASD meet DSM-5 diagnostic criteria for DCD, using a combination of parent-reports and standardized clinical tests. We compared motor profiles and impact of motor problems on daily living in ASD and DCD. We also compared social communication skills in both groups.

Methods: Thirty-seven individuals participated in this study, 27 diagnosed with ASD (Male = 21) and 10 diagnosed with DCD (Male = 9). We assessed all 4 criteria for a DCD diagnosis based on the DSM-5. All participants completed three assessments: The Movement Assessment Battery for Children – 2^nd ed. (MABC-2) for motor profiles, the Developmental Coordination Disorder Questionnaire (DCD-Q) for impact of motor problems on daily living. Both assess criteria A and B of the DSM-5, respectively. We used the Social Communication Questionnaire (SCQ) to assess social communication skills. In addition, we asked about delays in early milestones (crawling and walking) for Criterion C, and ruled out all neurological impairments (Criterion D) in both groups.

Results: Independent t-tests indicated no significant differences (p < 0.05) between the groups on the MABC-2 total percentile, with all individuals fitting the cut-off score for DCD (ASD: 6.69±16.81; DCD: 1.62±2.68). However, individuals with ASD scored significantly higher than those with DCD on the DCD-Q, indicating a lower impact of their motor deficits on daily living for this population (ASD: 37.32±11.60; DCD: 28.9±5.38). As expected, individuals with ASD scored significantly higher than those diagnosed with DCD (ASD: 20.04±6.53; DCD: 6.60±5.23) on the SCQ. Results on the early motor milestones indicated that the majority of the individuals in both groups did not have delays, but most individuals with ASD were close to the cut-off for a delay in waking (walked close to 18 months).

Conclusions: We conclude that all individuals in our sample could potentially be diagnosed with DCD in addition to ASD. We recommend that the evaluation of potential DCD in individuals with ASD be performed systematically and thoroughly, so as to distinguish this co-occurring condition from sensorimotor symptoms associated with ASD. The implications of a DCD diagnosis on individuals with ASD. This will aid clinicians in making important choices about intervention, informed by the distinction between individuals with co-occurring ASD+DCD and individuals with ASD who display some motor differences but do not meet criteria for DCD.