Sensory Processing in Adult ADHD – A Systematic Review

Abstract BackgroundThe way we perceive our environment is driven by our sensory nervous system and our attentional resources. Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, impulsivity, and hyperactivity. While cognitive and behavior dysfunctions have broadly been investigated, sensory processing has received less scientific attention. It has been shown, that children with ADHD show processing and modulatory deficits in multiple sensory domains, but very few studies examine to what extent these deficits persist in adult life. We conducted a systematic review of studies investigating sensory processing in adult ADHD.Main BodyUsing the keywords ‘ADHD’ and ‘sensory processing’, Web of Science and MEDLINE database were systematically searched for all articles published up to March 2020. 53 studies were included. Mostly, visual and auditory processing are studied, few investigated multisensory audiovisual and somatosensory processing. In summary, adult ADHD is marked by increased sensory gaining and deficient sensory inhibition. These disturbed gaining and inhibitory mechanisms were most prominent in the auditory modality but also visual modality impairment in terms of stimuli modulation were evident. Electrophysiological studies show alterations across all event-related potential (ERP) components associated with distractibility at early components (bottom-up) and inhibition and stimulus discrimination at later components (top-down). Brain imaging studies on sensory processing in ADHD are scarce, few pointing to higher resting state functional connectivity in visual areas and visual crossmodal activation for auditory stimuli. ConclusionSensory processing deficits extent from childhood to adult ADHD. These deficits are mainly driven by higher distractibility by irrelevant stimuli and modulatory impairment for relevant stimuli. In future studies, the relation of impaired bottom-up and top-down attentional mechanisms should be investigated and how they contribute to sensory processing deficits and clinical symptomatology in adult ADHD. This could help to gather more information about the underling processing deficits, so that specific adjusted training can be provided, that helps to overcome deficits in daily life functioning in e.g., not producing appropriate adaptive responses in social settings.Trial registrationN/A