Elevated unanticipated acoustic startle reactivity in dyslexia

People with dyslexia, a neurodevelopmental disorder of reading, are highly attuned to the emotional world. Compared to their typically developing peers, children with dyslexia exhibit greater autonomic nervous system reactivity and facial behavior to emotion- and empathy-inducing film clips. Affective symptoms, such as anxiety, are also more common in children with dyslexia than in those without. Here, we investigated whether the startle response, an automatic reaction that lies at the interface of emotion and reflex, is elevated in dyslexia. We measured facial behavior, electrodermal reactivity (a sympathetic nervous system measure), and emotional experience in response to a 100 ms, 105 dB unanticipated acoustic startle task in 30 children with dyslexia and 20 comparison children without dyslexia (aged 7-13) who were matched on age, sex, and nonverbal reasoning. Our results indicated that the children with dyslexia had greater total facial behavior and electrodermal reactivity to the acoustic startle task than the children without dyslexia. Across the sample, greater electrodermal reactivity during the startle predicted greater parent-reported anxiety symptoms. These findings contribute to an emerging picture of heightened emotional reactivity in dyslexia and suggest accentuated sympathetic nervous system reactivity may contribute to the elevated anxiety that is often seen in this population.