Estimates of the prevalence of speech and motor speech disorders in persons with complex neurodevelopmental disorders.

ABSTRACT

Estimates of the prevalence of speech and motor speech disorders in persons with complex neurodevelopmental disorders (CND) can inform research in the biobehavioural origins and treatment of CND. The goal of this research was to use measures and analytics in a diagnostic classification system to estimate the prevalence of speech and motor speech disorders in convenience samples of speakers with one of eight types of CND. Audio-recorded conversational speech samples from 346 participants with one of eight types of CND were obtained from a database of participants recruited for genetic and behavioural studies of speech sound disorders (i.e., excluding dysfluency) during the past three decades. Data reduction methods for the speech samples included narrow phonetic transcription, prosody-voice coding, and acoustic analyses. Standardized measures were used to cross-classify participants' speech and motor speech status. Compared to the 17.8% prevalence of four types of motor speech disorders reported in a study of 415 participants with idiopathic Speech Delay (SD), 47.7% of the present participants with CND met criteria for one of four motor speech disorders, including Speech Motor Delay (25.1%), Childhood Dysarthria (13.3%), Childhood Apraxia of Speech (4.3%), and concurrent Childhood Dysarthria and Childhood Apraxia of Speech (4.9%). Findings are interpreted to indicate a substantial prevalence of speech disorders, and notably, a substantial prevalence of motor speech disorders in persons with some types of CND. We suggest that diagnostic classification information from standardized motor speech assessment protocols can contribute to research in the pathobiologies of CND. Abbreviations 16p 16p11.2 deletion and duplication syndrome; 22q 22q11.2 deletion syndrome; ASD Autism Spectrum Disorder; CAS Childhood Apraxia of Speech; CD Childhood Dysarthria; CND Complex Neurodevelopmental Disorder; DS Down syndrome; FXS Fragile X syndrome; GAL Galactosemia; IID Idiopathic Intellectual Disability; MSD Motor Speech Disorder; No MSD No Motor Speech Disorder; NSA Normal(ized) Speech Acquisition; PEPPER Programs to Examine Phonetic and Phonologic Evaluation Records; PSD Persistent Speech Delay; PSE Persistent Speech Errors; SD Speech Delay; SDCS Speech Disorders Classification System; SDCSS Speech Disorders Classification System Summary; SE Speech Errors; SMD Speech Motor Delay; SSD Speech Sound Disorders; TBI Traumatic Brain Injury.