Cognitive predictors of medical decision-making capacity in traumatic brain injury.

OBJECTIVE: To identify cognitive predictors of medical decision-making capacity (MDC) in participants with traumatic brain injury (TBI) at time of acute injury (baseline) and at six-month follow-up. PARTICIPANTS: At baseline, participants were 34 adults with moderate to severe TBI and 20 healthy adults. At six-month follow-up, participants were 24 adults with moderate to severe TBI and 20 normal adults. MAIN OUTCOME MEASURES: Participants were administered a consent capacity instrument (Capacity to Consent to Treatment Instrument: CCTI) and neuropsychological test measures. In the TBI group, univariate and multivariate cognitive predictor models were developed at baseline and six-month follow-up for clinically relevant CCTI consent abilities/standards (S) of understanding (S5); reasoning (S4); and appreciation (S3). RESULTS: At baseline, measures of short-term verbal memory and semantic fluency predicted TBI group performance on understanding (S5); short-term verbal memory and attention predicted performance on reasoning (S4); and working memory predicted performance on appreciation (S3). Regarding six-month follow-up models, measures of basic executive function, verbal processing speed, and working memory predicted TBI performance on understanding (S5); working memory and short-term memory predicted reasoning (S4); and basic executive functioning predicted appreciation (S3). CONCLUSIONS: Multiple cognitive functions are associated with acute impairment and partial recovery of MDC in patients with moderate to severe TBI. Short-term verbal memory was strongly associated with impairments in consent capacity in TBI participants at the time of acute inpatient hospitalization. As patients experience cognitive and functional recovery post-hospitalization, executive functioning and working memory abilities were associated with improved capacity at six-month follow-up. The results offer insight into the relationship between different standards of competency and cognitive changes and recovery following acute TBI.