RELATIVELY PRESERVED HIPPOCAMPAL GLUCOSE-METABOLISM IN MILD ALZHEIMERS-DISEASE

The purpose of this study was to clarify the changes in hippocampal gl ucose metabolism in mild Alzheimer's disease (AD) using positron emiss ion tomography (PET) and 2-(F-18)fluoro-2-deoxy-D-glucose (FDG). Forty -one patients with probable mild AD (age: 69.0 +/- 8.0 years; MMSE: 22 .6 +/- 2.1) and 22 normal volunteers (age: 67.7 +/- 7.1 years) were st udied. The regional cerebral metabolic rate for glucose (CMRglc) was m easured using FDG and PET, Although the mean CMRglc in the parietal re gion was significantly lower in the AD group (right: 6.35 +/- 1.26 mg/ 100 g/min; left: 6.37 +/- 1.21 mg/100 gl min) than in the control grou p (right: 7.73 +/- 1.02 mg/100 g/min; left: 7.63 +/- 0.95 mg/100 g/min ), the mean CMRglc in the hippocampus did not show a significant diffe rence between the AD group (right: 4.58 +/- 0.70 mg/100 g/min; left: 4 .63 +/- 0.67 mg/100 g/min) and the control group (right: 5.22 +/- 0.65 mg/100 g/min; left: 5.22 +/- 0.67 mg/100 g/min) by analysis of varian ce and post-hoc Tukey's test. The magnitude of the hippocampal CMRglc reduction was not as large as that of parietal CMRglc reduction. Stati stical parametric maps (SPM) analysis also did not significantly demon strate reduced hippocampal CMRglc in AD patients, although it did show a significant reduction in parietal CMRglc in AD patients. Hippocampa l CMRglc was not significantly decreased in mild AD. This was unexpect ed in view of previous studies that have shown atrophy and clinical dy sfunction concerning hippocampus in AD, and suggests that the pathophy siology of the hippocampus in AD may be more complex than was previous ly thought.