Decisional capacity in young people with first episode psychosis, major depressive disorder and no mental disorder.

We aimed to (1) examine decisional capacity for treatment in young people (aged 15 to 25 years) with first-episode psychosis (FEP), Major Depressive Disorder (MDD) and no mental disorder, and (2) determine which theoretically relevant factors are associated with, and predict decisional capacity. We assessed decisional capacity (using MacArthur Competence Assessment Tool-Treatment; MacCAT-T), cognitive abilities, insight and symptom severity in young people with no mental disorder (n = 38), MDD (n = 38) and FEP (n = 18) from inpatient and outpatient services. Most young people with MDD (84.2%) or no mental disorder (86.8%) had adequate decisional capacity to consent to treatment based on recommended cut-off scores, compared with fewer than half of the those with FEP (44.4%). Levels of capacity were not significantly different between young people with MDD and those with no mental disorder (p = .861). However, young people with FEP demonstrated significantly poorer decisional capacity than those with no mental disorder (p = .006) and MDD (p = .009). A hierarchical regression analysis suggested that differences may be better explained by variation in cognitive ability, especially thematic verbal recall. Greater symptom severity and poorer insight were associated with poorer decisional capacity for FEP (p = .008 and p < .001, respectively), but not MDD (p = .050 and p = .805, respectively). Cognitive performance (i.e., predicted IQ, processing speed, mental flexibility and thematic verbal memory) collectively explained 36.6% of the variance in decisional capacity (p < .001). Thematic verbal memory was the strongest predictor of decisional capacity (p < .001). Supports for memory should be implemented to facilitate involvement in treatment decisions during the early course of illness.