A path-analytical approach to differentiate between direct and indirect drug effects on negative symptoms in schizophrenic patients

A re-evaluation of the North American risperidone study
  • Hans-Jürgen Möller
  • Horst Müller
  • Richard L. Borison
  • Nina R. Schooler
  • Guy Chouinard
Original Paper


The hypothesis that differences in drug effects of risperidone and haloperidol on negative symptoms in schizophrenia are secondary to effects on positive, extrapyramidal, and depressive symptoms was investigated by means of an analysis of the data from the USA-Canada risperidone double-blind randomized clinical trial of 523 chronic schizophrenic patients. Regression analyses in the total sample and within treatment groups confirmed a strong relationship between changes in negative symptoms and the other variables studied (R2=0.50−0.51,p<0.001). Only depressive symptoms did not contribute significantly to these results (p>0.10). Path analysis showed that the greater mean change (p<0.05) of negative symptoms with risperidone compared to haloperidol could not be fully explained by correlations with favourable effects on positive and extrapyramidal symptoms. The relationship between shift in extrapyramidal symptoms and shift in negative symptoms failed to reach statistical significance; however, there was a clear tendency in the expected direction in both treatment groups.

Key words

Neuroleptics Negative symptoms Risperidone Schizophrenia Haloperidol 


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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Hans-Jürgen Möller
    • 1
  • Horst Müller
    • 2
  • Richard L. Borison
    • 4
  • Nina R. Schooler
    • 5
  • Guy Chouinard
    • 3
  1. 1.Department of PsychiatryLudwig Maximilian University of MunichMunichGermany
  2. 2.Department of PsychiatryUniversity of BonnBonnGermany
  3. 3.Louis-H Lafontaine HospitalUniversity of Montreal and McGill UniversityMontrealCanada
  4. 4.Department of Psychiatry and Health BehaviorMedical College of GeorgiaAugustaUSA
  5. 5.School of Medicine, Western Psychiatric Institute and ClinicUniversity of PittsburghPittsburghUSA

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