To study mathematical deficits in the early stages of Alzheimer's disease (AD).
Sixty-eight patients with mild AD and 242 normal controls (NC) received a standardized battery (EC 301-R) assessing number processing and calculation abilities. AD patients also received testing for language, memory, visuo-spatial and executive-attentional domains.
Sixty-four AD patients (94.1%) showed impaired performances on the EC 301-R. Mathematical deficits were evident both on calculation and number processing skills. Performance on the single tasks was related to attentional-executive resources and to impaired number representations. Heterogeneous patterns of preserved/impaired mathematical abilities were also observed in single cases.
Dyscalculia is an early sign of AD. It should be included among the reliable clinical hallmarks for the diagnosis of AD. Identification of dyscalculic symptoms in these patients requires composite assessment procedure.
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