Participants with schizophrenia retain the information necessary for informed consent during clinical trials

Cognitive impairment is a characteristic of schizophrenia. This impairment may affect the retention of information required for ongoing knowledgeable participation in clinical trials. This study monitored retention of study-related knowledge-including assessment of therapeutic misconception-in people with stable, DSM-IV schizophrenia during participation in placebo-controlled clinical trials of adjunctive agents. Stability was defined as being on an antipsychotic with no change in medication or dose over the previous 4 weeks.

This longitudinal study assessed retention of clinical trial-related consent information. Individuals enrolling in 1 of 8 clinical trials were approached for participation. Participants came from research clinics and community mental health centers. At baseline, clinical trial consent forms were reviewed and study knowledge assessed. Participants were randomized to follow-up assessments at weeks 1, 4, and 8; weeks 4 and 8; or at week 8 only. Clinical trial consent forms were not rereviewed at any follow-up visit.

Fifty-nine participants were enrolled; analysis included 52 participants with at least 1 follow-up visit. Study knowledge did not decrease meaningfully in any group. Therapeutic misconception was not observed in participants during the study. The group assessed most frequently demonstrated significant improvement over baseline (t44 = 3.43, P = .001). Retention of study knowledge was not related to symptoms but had a weak correlation with cognitive capacity (R = 0.28, P = .07). Performance did not differ between participants from research clinics and those from community mental health centers.

Clinically stable people with schizophrenia enrolling in a placebo-controlled adjunctive medication study, once determined to have capacity to consent to a clinical trial, retained appropriate study knowledge for at least 8 weeks. In the absence of a specific reason to suspect a loss of decisional capacity, there appears to be no need to routinely reevaluate participants during this type of clinical trial.