A new spatial orientation memory test: Evaluation in patients with mild Alzheimer’s disease and in patients with operated and unoperated mesial temporal lobe epilepsy

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Background and objectives: Spatial orientation and spatial learning depend on the medial temporal lobe. A new test of spatial memory in humans is described, and applied to patients with Alzheimer’s disease (AD), with presumable damage of that region, and to patients with unilateral mesial temporal sclerosis (MTS) submitted or not to treatment by selective surgical amygdala-hippocampectomy (SAH).Methods: Subjects were asked to go to each of four objects hanging from the wall of a room: a cylinder, a square, a ball and a triangle (trial 1). In trial 2 they repeated this blindfolded; all figures except the cylinder were removed; once the subjects reached the cylinder they had to say what figures should be at the left, right and back. In trial 3, all figures were withdrawn and the subjects, again blindfolded, were instructed first to go to the front, right, left and back, and then to go to the former positions occupied by the cylinder, the ball, the square and the triangle. Results: Experiment 1 studied 10 patients with mild AD and 10 controls matched by age, gender and schooling. Performance was 46% lower in AD patients relative to controls (p <0.001). Experiment 2 studied 23 patients with MTS, 20 patients submitted to SAH, and 23 healthy volunteers with similar levels of age, gender and schooling. No differences in performance among these three groups were observed. Conclusions: The test distinguished performance deficits of AD patients relative to controls, but not among MTS and STH patients and controls