Cognitive functioning and adjudicative competence: defendants referred for neuropsychological evaluation in a psychiatric inpatient setting

Objective: A paucity of peer-reviewed research exists regarding the relation between cognitive functioning and adjudicative competence, despite increasing awareness of cognitive deficits associated with serious mental illness. This retrospective study sought to add to and expand upon existing research by considering performance validity and court determinations of competence, when available. Method: We compared demographic and cognitive variables of a group of defendants with presumed valid testing admitted to an inpatient psychiatric facility for evaluation of adjudicative competence and referred for neuropsychological evaluation (n=45) and compared individuals determined by the evaluator and/or the court to be competent (n=30) and incompetent (n=15). Results: Defendants who were incompetent were more likely to be diagnosed with a cognitive disorder, with a medium effect size. There was a difference in tests of immediate and delayed memory as measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), with medium to large effects, and high delayed memory scores were helpful in ruling out incompetence (Negative predictive power=85.71%). Conclusions: These results provide support for the relationship between cognitive functioning and trial competence, particularly at high and low levels of performance.