A Longitudinal SPECT Study of Different Patterns of Regional Cerebral Blood Flow in Alzheimer's Disease with or without Diabetes

AIMS To determine the effect of diabetes mellitus (DM) on regional cerebral blood flow (rCBF) patterns in patients with Alzheimer's disease (AD). METHODS We investigated the initial rCBF of 71 AD patients (36 without DM and 35 with DM) and the final rCBF of 23 AD patients (12 without DM and 11 with DM) after an average of 32 months. Single-photon emission computed tomography (SPECT) data were analyzed by statistical brain imaging. RESULTS The initial SPECT showed that AD patients without DM had lower rCBF in the left and right inferior temporal gyri than AD patients with DM. A follow-up SPECT demonstrated that rCBF decreased in more widespread regions, including the parietal, temporal, frontal, and limbic lobes, in AD patients without than with DM. CONCLUSION This study suggests that functional brain abnormalities in AD differ depending on the DM status at baseline and during follow-up, reflecting neuropathologic differences.