[Usefulness of SPECT in the study of Alzheimer's disease]

Single-photon emission photometry (SPECT) images of the brains of 60 patients with Alzheimer's disease (AD) were compared with the brain scans of 16 healthy controls of the same sex and similar ages. SPECT was repeated one year later in 16 of the AD patients. Perfusion indices for frontal, parietal, temporal and occipital regions of patients and controls were compared (Student's tests). Flow alterations were located and symmetry examined. The correlation between perfusion index for each cortical area and MMSE score was assessed (Pearson's r). Perfusion alterations were present in all except one AD patient, and in 65% of AD patients such alterations were in the parietotemporal cortex. Severity of cognitive impairment in AD patients was related to perfusion changes in the left posterior temporal region. Forty-four AD patients showed asymmetrical distribution of tracer and in 73% perfusion changes were predominantly in the left hemisphere. Altered brain blood flow is common in AD and onset is early. The parietotemporal location of defective perfusion is of great diagnostic value. Asymmetry is common and the left hemisphere is most often affected.