Everyday numerical abilities in Alzheimer's disease.

The present study investigated everyday numerical abilities in a group of 21 patients affected by mild to moderate dementia of Alzheimer's type (DAT). Though patients did not differ from a control group in standard laboratory tests tapping transcoding, number comparison, simple calculation, and estimation, they showed significant difficulties in numerical tasks embedded in an everyday context, such as handling money, a bus schedule, or a television program. Patients' difficulties were attributed to those multiple cognitive demands which are inherent to real situations as compared to well-structured abstract paper-and-pencil tasks. Overall, the study suggests that the examination of numerical abilities in DAT patients should go beyond abstract paper-and-pencil tasks which can only partially reflect the actual numerical skills in DAT and should therefore include also tasks simulating everyday life situations. Assessment of everyday numerical skills may be crucial in planning adequate support for patients, for example in handling money, but also in designing targeted training programs.