Benefits and harms of providing biological causal models in the treatment of psychosis – An experimental study

Background and objectivesAlthough many studies have investigated the impact of causal models on public attitudes toward people with psychosis, the effect of causal models on patients with psychosis is unclear. Clinicians must therefore decide about providing causal information without knowing how it will impact on patient and treatment. This study investigates the effect of causal models on different aspects of treatment motivation.MethodsIn an experimental online study healthy individuals (n = 461) were instructed to imagine experiencing psychotic symptoms and seeking professional help. The imagination was supported by an audio play cover story. Subsequently, participants were randomized to four conditions differing in the content of the causal model given for the occurring symptoms (biological, psychological, combined and no causal explanation).ResultsDifferent causal models impacted on different aspects of treatment motivation: Participants who had received a biological causal model showed high willingness to take medication, whereas participants who had received a psychological model reported high perceived personal control over symptoms. Participants who had received a causal model that combined biological and psychological aspects reported high acceptance of medication and high motivation to undergo treatment by this clinician.ConclusionsThe results underline the impact the content of a causal model may have on patients’ treatment motivation and - as a consequence - on treatment success. Overall, the integration of psychological and biological aspects within a causal model seems most promising in terms of adherence to various types of treatment.

► Healthy individuals imagine experiencing psychotic symptoms.
► We randomly present manipulated causal models for the symptoms.
► We assess different aspects of the participants’ potential treatment motivation.
► The content of causal models determines specific treatment motivation.
► Combining psychological and biological causes in a model appears most beneficial.