Random number generation in dementia of the Alzheimer type: A test of frontal executive functions

• Published in: Neuropsychologia 1996-02, Vol.34 (2), p.97-103
• Main Authors: Brugger, P, Monsch, A.U, Salmon, D.P, Butters, N
• Format: Article
• Language: English
• Subjects: Aged; Alzheimer Disease - complications; Alzheimer Disease - physiopathology; Alzheimer type dementia; Cognition Disorders - diagnosis; Cognition Disorders - etiology; Female; Frontal Lobe - physiopathology; frontal lobes; Humans; Male; Neuropsychological Tests; random generation; review; Task Performance and Analysis
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/0028-3932(95)00066-6

The quality of attempts at generating a random sequence of the numbers 1–6 was studied in 30 patients with dementia of the Alzheimer type (DAT) and 30 elderly normal control (NC) subjects. Three main findings emerged: (1) DAT patients' subjective random sequences were more stereotyped (contained fewer digit combinations) than those of NC subjects. (2) This difference in response stereotypy was due to patients' enhanced tendency to arrange consecutive numbers in an ascending series (‘counting bias’). (3) In the patient group, degree of sequential nonrandomness was positively correlated with overall severity of dementia and with the extent to which performance on neuropsychological tests specifically assessing executive functions (fluency, naming, error monitoring) was impaired. These results illustrate a loss of behavioral complexity in the course of dementia and are interpreted as reflecting a frontal dysexecutive syndrome in DAT.