Another limitation was that, because of the limited sample size,
we had to limit the number of variables included as predictors in
the regression models. Therefore, we could not explore the pre-
dictive value of different psychopathic traits (e.g. Factor 1 and 2)
and of the different substances. Future research may test the
predictive value of different aspects of psychopathy, and of dif-
ferent substances. A third limitation was that the time frame of
aggression on the ward was very short. That is, we only included
data on aggression on the ward following one week after inclu-
sion. This limits the predictive value for future aggression on the
ward that one can assign to the current results. A last limitation of
this study was that the patients were not medication free. The
psychotropic effect of the medicine may have influenced their
aggressive responding, on the self-report measures as well as on
the PSAP task, and on the ward. But note that all patients received
prescribed antipsychotic medication. But note that all patients
received prescribed antipsychotic medication.
One of the strengths of this study is that, to our knowledge, this
is the first study that examined the predictive value of multiple
factors in different measures of aggressive behavior in persons
with schizophrenia. This has led to more insight in why some
results regarding the association between schizophrenia and ag-
gressive behavior are inconsistent. Also, the present results point
to the importance of acknowledging different motives for ag-
gressive behavior in patients with a schizophrenia disorder.