In a recent study on individuals with schizophrenia it was found that errors due to cognitive difficulties were uncommon and significantly impair decision making capacity. For example, 65.5 percent of individuals undergoing the MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR) made errors resulting from difficulty recalling study information and 22.6 percent overemphasized the potential for personal gain from study participation.
Individuals' "responses were also notable for the errors they did not make," the researchers noted. "Ethical concerns have been raised surrounding the notion that psychotic symptoms per se (e.g., delusional thinking) might impede the capacity for decision-making. However, in the present analyses, no evidence supports detrimental effects of psychosis on decisional capacity for research participation among this outpatient sample."
Additionally, 90.5 percent of participants understood that the study was voluntary after hearing the study information only once. When the information was repeated, all but one participant understood the voluntary nature. "Despite concerns regarding the potential for coercion, the fact that the vast majority of participants in the present study recognized the voluntary nature of participation suggests that perceived coercion is uncommon," the researchers commented.
Based on their findings, the researchers identified ways to increase the likelihood that individuals with schizophrenia will make informed decisions about participating in research. Though 55 of the 84 participants made errors in recalling study information, repetition of relevant information led to perfect or nearly perfect recall in 36.4 percent of them; 47.3 percent had improvements in recall, though they continued to miss important details. The researchers concluded that "given difficulties some individuals have with recalling information conveyed during the consent process, key study information should be highlighted and repeated to them."
As this study was limited to stable outpatients with mild to moderate psychiatric symptoms, the results cannot be extrapolated to inpatient or acutely ill populations.