To assess sensory processing anomalies in neurotypical children, children with autism spectrum disorder, and attention-deficit hyperactivity disorder, particularly within the vibrotactile and auditory sensory modalities.

Neurodevelopmental disorders, such as attention-deficit-hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), have been associated with a high prevalence of sensory processing anomalies. With the update of the diagnostic manuals International Classification of Diseases eleventh revision (ICD-11) and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V), more emphasis has been given to the sensory symptoms of both these disorders. The demand of reliable and valid quantitative measurements of sensory processing anomalies are therefore increasing as such metrics has the potential to assist clinical decision-making e.g., in (differential) diagnostics and treatment response evaluation and prediction. The present observational study focuses on auditory and tactile processing. Hearing and touch are two of the most frequency reported modalities in which individuals with ASD experience sensory anomalies. In addition, adequate auditory and tactile processing are presumed fundamental in the emergence of various social and cognitive functions such as the development of language. Elucidating the sensory symptoms by means of psychophysics, neuroimaging, and quantitative measures of peripheral sensory organs could elucidate the underlying (neuro)physiology of sensory anomalies in ASD and ADHD.

The present project aims to elucidate the physiological substrates of abnormal sensory processing by conducting a battery of tests in children with ASD, ADHD, and neurotypical children. First, a series of questionnaires will be administered to acquire a (clinical) description of the participants (Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V); Autism Quotient (AQ, child version); Childhood Behavioral Checklist (CBCL 6-16); ADHD-Ration Scale (ADHD-RS); Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2); Use of pharmacotherapy). A standardized caregiver-reported sensory profile questionnaire will serve as the primary outcome (Sensory Profile 2, Child version). Second, transiently evoked otoacoustic emissions will be measured in order to account for peripheral mechanisms of hearing as well as their contralateral suppression to measure efferent auditory system functioning. Third, a psychophysic task will be conducted for the purpose of estimating the just-noticeable difference to auditory loudness and vibrotactile displacement intensities followed by a subjective categorical loudness scale experiment. Finally, two electroencephalographic experiments will be performed: a frequency tagging paradigm with interspersed pitch oddballs and a classical sensory gating paradigm using vibrotactile stimuli and auditory clicks.

Inclusion Criteria:

• Clinically diagnosed with either ADHD, ASD, or no diagnosis (typical development)
• Between 8-15 years old

Exclusion Criteria:

• Familiar history of schizophrenia and depression.
• Epilepsy, cerebral palsy, traumatic brain injury
• Musculoskeletal illnesses
• Hearing or visual impairment that cannot be corrected
• Lack of ability to cooperate
• Parents cannot read Danish

The study population include three well-defined groups of subjects:

1. Children with a diagnosis of ASD from the local Child and Adolescent Psychiatry clinic.
2. Children with a diagnosis of ADHD from the local Child and Adolescent Psychiatry clinic.
3. Neurotypical children without any psychiatric or neurologic diagnosis.