Abnormalities of the acoustic startle reflex and reaction time in Gilles de la Tourette syndrome

Objective: To study the startle reflex and the effect of the startle reflex stimulus over reaction time (start-react effect) in Gilles de la Tourette syndrome (GTS). Method: Ten GTS patients and ten matched healthy volunteers underwent a sim ple RT paradigm (4 blocks of 50 trials). Forty acoustic startle reflex stim uli (110 dB) were randomly delivered with a 20% occurrence probability and presented unexpectedly at the same time as the imperative stimuli of the RT . Variables of interest were: amplitude, onset latency, degree of spread an d rate of habituation of the startle response, and RT and the start-react e ffect caused by the startle stimuli. Results: GTS patients showed a significantly higher amplitude, a major degr ee of spread and fewer habituation phenomena of the startle reflex. GTS pat ients showed poorer non statistically significant RT performance compared t o controls, with a significant correlation between RT and severity of the d isease. The start-react effect was significantly less pronounced in GTS pat ients. Conclusions: The present study confirms that GTS has an exaggerated startle reflex response and extend the spectrum of abnormalities to the start-reac t effect. A state of dopaminergic hyperactivity may have contributed to the se results. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.