Neuropsychological tests and [99mTc]-HM PAO SPECT in the diagnosis of Alzheimer's dementia

Twenty-three patients with Alzheimer's dementia (AD) in relatively early stages and 40 patients with other cognitive disorders of vascular or degenerative aetiology underwent neuropsychological examination and [^99mTc]-HM PAO single photon emission computed tomography (SPECT). In contrast to the commonly accepted notion of a posterior temporoparietal reduction of tracer uptake as the typical SPECT pattern of AD, the most consistent feature found in the SPECT images of our AD patients was a hippocampal uptake deficit, associated with a variable degree of temporal, parietal and frontal deficit (extending from the posterior to the anterior regions), according to the severity of the disease. These results support the theory of AD as a "hippocampal dementia", at least in the early stages. Neuropsychological tests were found to be somewhat more specific and more accurate than SPECT in distinguishing AD from non-AD cases.