Elsevier

Biological Psychiatry

Volume 55, Issue 5, 1 March 2004, Pages 518-523
Biological Psychiatry

Original article
Prepulse facilitation and prepulse inhibition in schizophrenia patients and their unaffected siblings

https://doi.org/10.1016/j.biopsych.2003.10.018Get rights and content

Abstract

Background

Deficits in schizophrenia patients and their first-degree relatives have been reported in prepulse inhibition (PPI), a phenomenon that measures an early stage of information processing (sensorimotor gating). It is less clear whether these information processing deficits extend to prepulse facilitation (PPF), which measures a later stage of generalized alerting or orienting.

Methods

This study examined three separate issues: first, whether schizophrenia patients have deficits in PPI and PPF; second, whether the siblings of patients show deficits in these processes; and third, whether prepulse duration influences the degree of the deficits. These issues were examined in 76 schizophrenia patients, 36 of their siblings, and 41 normal control subjects.

Results

Patients and siblings did not differ from control subjects in PPI, perhaps due to the use of different procedural parameters compared with other laboratories that have consistently found PPI deficits in schizophrenia patients. Patients and their siblings produced significantly less PPF than control subjects. For both PPI and PPF, prepulse duration was not a significant factor.

Conclusions

These results imply that PPF deficits reveal a generalized alerting or orienting deficit that is present in both schizophrenia patients and their siblings, suggesting that this deficit may be tapping an endophenotypic vulnerability factor.

Section snippets

Participants

Participants initially included 90 schizophrenia patients, 48 of their siblings (sharing both biological parents of the schizophrenia proband), and 47 nonpatient control subjects. Subjects were drawn from a larger study of Early Visual Processing in Schizophrenia (principal investigator: M.F. Green); schizophrenia probands were recruited from outpatient clinics at the Greater Los Angeles Veteran's Administration (VA) Healthcare System and through presentations in the community. Nonpatient

Subject exclusions

Before any statistical analysis, subjects with blink amplitudes less than an average of 2.0 μV to startle-alone trials (based on the average of all 15 ITI startle-alone trials) were considered nonresponders and were excluded from further analysis (14 patients, 7 siblings, and 6 control subjects met this criterion). The following number of subjects comprised each group after exclusions: 76 (2 female) patients, 36 (19 female) siblings, and 41 (22 female) normal control subjects.

Demographic data

Descriptive data

Discussion

The three major findings of this paper are the following: 1) deficient PPF was found in schizophrenia patients and their siblings; 2) intact PPI was found in schizophrenia patients and their siblings, a finding contrary to many published studies finding PPI deficits in such groups; and 3) these findings were obtained regardless of the duration of the prepulse (i.e., discrete white noise vs. continuous tone).

The principal new finding of this study was the deficient PPF exhibited by both

Acknowledgements

This research was supported by Grant Nos. MH-46433 (MED) and MH-43292 (MFG) and by the Department of Veterans Affairs, Veterans Integrated Services Network 22 Mental Illness Research, Education, and Clinical Center. JKW was supported by a National Institute of Mental Health National Research Service Award Training Grant No. MH14584 (principal investigator: Keith H. Nuechterlein) during preparation of this article. We thank Bill Troyer for technical assistance and programming.

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