Visuospatial planning and problem solving in Alzheimer's disease patients: a study with the Tower of London Test

Background: Executive dysfunction in Alzheimer's disease (AD) has been recently recognized as an early and prominent clinical sign. The Tower of London (ToL), a task specifically devised to test executive functions of visuospatial planning and problem solving, has frequently been used in neuropsychological experiments, but rarely in the clinical ground. Methods: One hundred and sixty-one AD patients and 212 nondemented healthy controls were administered a simplified ToL version. Results: AD patients were significantly impaired (p < 0.0001) in all ToL scores and in the total execution time. The 'accuracy' score of ToL at a cut off of <= 29/36 yielded a sensitivity of 71.2% and a specificity of 76.4% (AUC 0.79) for the diagnosis of AD versus controls. Conclusions: Visuospatial planning and problem solving are significantly impaired in early dementia of the Alzheimer's type. A successful sensitivity/specificity ratio, the independence of education and the simplicity of this version of ToL make it a useful executive functioning screening test for early AD. Copyright (c) 2007 S. Karger AG, Basel.