Dissociative identity disorder and prepulse inhibition of the acoustic startle reflex

Karl Yngvar Dale1, Magne Arve Flaten1, Åke Elden1, Arne Holte21Department of Psychology, University of Tromsø, Norway; 2The Norwegian Institute of Public Health, Department of Mental Health, Oslo, Norway and University of Oslo, NorwayAbstract: A group of persons with dissociative identity disorder (DID) was compared with a group of persons with other dissociative disorders, and a group of nondiagnosed controls with regard to prepulse inhibition (PPI) of the acoustic startle reflex. The findings suggest maladaptive attentional processes at a controlled level, but not at a preattentive automatic level, in persons with DID. The prepulse occupied more controlled attentional resources in the DID group compared with the other two groups. Preattentive automatic processing, on the other hand, was normal in the DID group. Moreover, startle reflexes did not habituate in the DID group. In conclusion, increased PPI and delayed habituation is consistent with increased vigilance in individuals with DID. The present findings of reduced habituation of startle reflexes and increased PPI in persons with DID suggest the operation of a voluntary process that directs attention away from unpleasant or threatening stimuli. Aberrant voluntary attentional processes may thus be a defining characteristic in DID.Keywords: dissociation, DID, PPI, startle, habituatio