title: Neuropsychologic predictors of competency in Alzheimer's disease using a rational reasons legal standard.
abstract: OBJECTIVE
  To identify neuropsychologic predictors of competency performance and status in Alzheimer's disease (AD) using a specific legal standard (LS). This study is a follow-up to the competency assessment research reported in this issue of the archives.
  
  
  METHODS
  Univariate and multivariate analyses of independent neuropsychologic test measures with a dependent measure of competency to consent to treatment.
  
  
  METHODS
  University medical center.
  
  
  METHODS
  Fifteen normal older control subjects and 29 patients with probable AD.
  
  
  METHODS
  Subjects were administered a battery of neuropsychologic measures theoretically linked to competency function, as well as two clinical vignettes testing their capacity to consent to medical treatment under five different LSs. The present study focused on one specific LS: the capacity to provide "rational reasons" for a treatment choice (LS4). Neuropsychologic test scores were correlated with scores on LS4 for the normal control group and the AD group. The resulting univariate predictors were then analyzed using stepwise 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 (R2 = .33) and the AD group (R2 = .36). A word fluency measure also emerged as the best single predictor of competency status for the full subject sample (n = 44), correctly classifying 82% of cases. Dementia severity (Mini-Mental State Examination score) did not emerge as a multivariate predictor of competency performance or status. Interestingly, measures of verbal reasoning and memory were not strongly associated with LS4.
  
  
  CONCLUSIONS
  Word fluency measures predicted the normative performance and intact competency status of older control subjects and the declining performance and compromised competency status of patients with AD on a "rational reasons" standard 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 competency function have important theoretical and clinical value.
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Marson
authors.forename: H A
authors.initials: HA
authors.lastname: Cody
authors.forename: K K
authors.initials: KK
authors.lastname: Ingram
authors.forename: L E
authors.initials: LE
authors.lastname: Harrell
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000523:psychology* / Q000628:therapy; D006801:Humans; D007258:Informed Consent; D016743:Mental Competency; D009483:Neuropsychological Tests / Q000592:standards*; D011237:Predictive Value of Tests