NEUROPSYCHOLOGIC PREDICTORS OF COMPETENCE IN ALZHEIMERS-DISEASE USINGA RATIONAL REASONS LEGAL STANDARD

Objective: To identify neuropsychologic predictors of competency perfo rmance and status in Alzheimer's disease (AD) using a specific legal s tandard (LS). This study is a follow-up to the competency assessment r esearch reported in this issue of the ARCHIVES. Design: Univariate and multivariate analyses of independent neuropsychologic test measures w ith a dependent measure of competency to consent to treatment. Setting : University medical center. Subjects: Fifteen normal older control su bjects and 29 patients with probable AD. Main Outcome Measures: Subjec ts were administered a battery of neuropsychologic measures theoretica lly linked to competency function, as well as two clinical vignettes t esting their capacity to consent to medical treatment under five diffe rent LSs. The present study focused on one specific LS: the capacity t o provide ''rational reasons'' for a treatment choice (LS4). Neuropsyc hologic test scores were correlated with scores on LS4 for the normal control group and the AD group. The resulting univariate predictors we re then analyzed using step-wise regression and discriminant function to identify the key multivariate predictors of competency performance and status under LS4. Results: Measures of word fluency predicted the LS4 scores of controls (R(2) = .33) and the AD group (R(2) = .36). A w ord fluency measure also emerged as the best single predictor of compe tency status for the full subject sample (n = 44), correctly classifyi ng 82% of cases. Dementia severity (Mini-Mental State Examination scor e) did not emerge as a multivariate predictor of competency performanc e or status. Interestingly, measures of verbal reasoning and memory we re not strongly associated with LS4. Conclusions: Word fluency measure s predicted the normative performance and intact competency status of older control subjects and the declining performance and compromised c ompetency status of patients with AD on a ''rational reasons'' standar d of competency to consent to treatment. Cognitive capacities related to frontal lobe function appear to underlie the capacity to formulate rational reasons for a treatment choice. Neuropsychologic studies of c ompetency function have important theoretical and clinical value.