title: Cognitive predictors of medical decision-making capacity in mild cognitive impairment and Alzheimer's disease.
abstract: OBJECTIVE
  Impaired capacity to make decisions in everyday life and situations of medical treatment is an inevitable consequence of the cognitive decline in Alzheimer's disease (AD). The objective of this study was to identify the most powerful cognitive component(s) that best predicted medical decision-making capacity (MDMC) in patients with AD and mild cognitive impairment.
  
  
  METHODS
  Three groups of subjects participated in the study: patients with AD (n = 20), mild cognitive impairment (n = 21), and healthy control subjects (n = 33). MDMC was assessed by the linguistic instrument for medical decision-making (LIMD) and related to demographics and 27 cognitive test measures.
  
  
  RESULTS
  The cognitive tests were found to aggregate into four components using a principle component analysis. The four components, which correspond to verbal knowledge, episodic memory, cognitive speed, and working memory, accounted for 73% of the variance in LIMD according to a stepwise regression analysis. Verbal knowledge was the most powerful predictor of LIMD (beta = 0.66) followed by episodic memory (beta = 0.43), cognitive speed (beta = 0.32), and working memory (beta = 0.23). The best single test as shown by the highest correlation with LIMD was Reading speed (R = 0.77).
  
  
  CONCLUSIONS
  Multiple factors are involved in MDMC in subjects with cognitive impairment. The component of verbal knowledge was the best predictor of MDMC and Reading speed was the most important single cognitive test measurement, which assessed both rapid Reading and understanding of text.
authors.affiliation: Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden; Department of Speech and Language Pathology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Sara
authors.initials: S
authors.lastname: Stormoen
authors.forename: Ove
authors.initials: O
authors.lastname: Almkvist
authors.forename: Maria
authors.initials: M
authors.lastname: Eriksdotter
authors.forename: Erik
authors.initials: E
authors.lastname: Sundström
authors.forename: Ing-Mari
authors.initials: IM
authors.lastname: Tallberg
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000523:psychology*; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000523:psychology*; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D016743:Mental Competency / Q000523:psychology*; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D012044:Regression Analysis
keywords: Alzheimer's disease; cognitive predictors; medical decision-making capacity; text reading; verbal knowledge