Startle magnitude and prepulse inhibition: effects of alcohol and attention

Background: Previous studies of the effects of attention on prepulse inhibition (PPI) have not accounted for the effects of attention on control (i.e. pulse alone) trials. In addition, there have been no studies of the effects of alcohol on the attentional modulation of PPI, even though alcohol putatively influences attentional mechanisms. The objective of the present study was to examine the effects of alcohol on the attentional modulation of PPI, using an experimental paradigm that controlled for the effects of attention on control trials. Methods: Participants completed two experimental sessions spaced 1 week apart and consumed either three alcoholic drinks (target BAL=0.06) or three non-alcoholic drinks. Participants were exposed to a series of prepulse and pulse alone stimuli and were instructed to either listen or ignore prior to each stimulus. Results: Repeated measures ANOVAs suggested that attention increased PPI and startle magnitude on pulse alone control trials. Alcohol decreased both startle magnitude and PPI. There was no significant interaction between attention and alcohol. Conclusions: These findings suggest that both startle magnitude and PPI are increased by attention and that failure to control for the effects of attention on control trials may result in an underestimation of the effect of attention on PPI. Furthermore, the effect of alcohol on attention does not appear to generalize to the voluntary attentional processes involved in the attentional modulation of PPI.