Understanding of Placebo Controls Among Older People With Schizophrenia

摘要

Research protocols frequently necessitate procedures or design elements that differ from those used in routine clinical care. An example is the inclusion of a placebo arm in many randomized clinical trials. Because there are risks to taking a placebo when one has a chronic disorder such as schizophrenia, ascertaining how well people with severe mental illness understand placebos is an important task for empirical research ethics. We investigated whether schizophrenia patients' understanding of placebo controls could be improved with a brief educational intervention. We randomized 49 middle-aged and older patients with schizophrenia or schizoaffective disorder to receive either (1) a routine explanation of placebos in the context of consent for a hypothetical double-blind placebo-controlled clinical trial, or (2) the consent for the hypothetical trial plus a brief educational module explaining placebos in more depth. Understanding of placebos was assessed with a 12-item questionnaire, and we examined demographic, clinical, neurocognitive, and decision-making correlates of understanding of placebos. Those participants who received the intervention obtained higher scores on the placebo post-test compared to those who received the standard information alone. Performance on the placebo post-test was positively correlated with measures of decisional capacity and neurocognitive abilities and negatively correlated with severity of negative symptoms, but it showed no relationship with positive or general symptoms. Some participants interpreted the common phrase “sugar pill” as relating somehow to diabetes. We conclude that the level of understanding of important research design–related information is not static but may be influenced by how investigators approach the consent process.