Mental calculation in mild Alzheimer's disease: A pilot study

The purpose of this study was to determine whether dyscalculia is present in the early stages of Alzheimer's disease (AD) and if it is associated with a characteristic neuropsychological pattern. We examined 28 probable AD patients with scores of 18 or greater on the Mini‐Mental State Examination (MMS) and with an educational level of 12 or more years. The ability to perform mental calculation was assessed by two tests: the Stamp Test (ST) and the Serial Seven Subtraction Test (SSST). The other cognitive domains were evaluated with an extensive neuropsychological battery. We found significant differences in performances on the calculation tests between patients and controls. The ST was correlated with attention and visuospatial skills, whereas the SSST was correlated with both receptive language and the MMS; both test were similarly correlated with productive language. This study suggests that impairment in mental calculation can be an early sign of AD. The ST seems to represent a more complex task dependent on attentional resources, whereas the SSST would be a purer measure of anarithmetia.