Error behaviors associated with loss of competency in Alzheimer's disease.
OBJECTIVE
To investigate qualitative behavioral changes associated with declining medical decision-making capacity (competency) in patients with AD.


BACKGROUND
Qualitative measures can yield clinical information about functional changes in neurologic disease not available through quantitative measures.


METHODS
Normal older controls (n = 21) and patients with mild and moderate probable AD (n = 72) were compared using a standardized competency measure and neuropsychological measures. A system of 16 qualitative error scores representing conceptual domains of language, executive dysfunction, affective dysfunction, and compensatory responses was used to analyze errors produced on the competency measure. Patterns of errors were examined across groups. Relationships between error behaviors and competency performance were determined, and neurocognitive correlates of specific error behaviors were identified.


RESULTS
AD patients demonstrated more miscomprehension, factual confusion, intrusions, incoherent responses, nonresponsive answers, loss of task, and delegation than controls. Errors in the executive domain (loss of task, nonresponsive answer, and loss of detachment) were key predictors of declining competency performance by AD patients. Neuropsychological analyses in the AD group generally confirmed the conceptual domain assignments of the qualitative scores.


CONCLUSIONS
Loss of task, nonresponsive answers, and loss of detachment were key behavioral changes associated with declining competency of AD patients and with neurocognitive measures of executive dysfunction. These findings support the growing linkage between executive dysfunction and competency loss.
Marson
D C
DC
Department of Neurology, Alzheimer's Disease Research Center, University of Alabama at Birmingham, 35233-7243, USA.
Annis
S M
SM
McInturff
B
B
Bartolucci
A
A
Harrell
L E
LE
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D016743:Mental Competency / Q000331:legislation & jurisprudence*; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics; D015203:Reproducibility of Results