A comparative study in Alzheimer's and normal brains of trace element distribution using PIXE and INA analyses and glucose metabolism by positron emission tomography

The onset of Alzheimer's disease has been shown to affect trace element con centrations in the brain when compared to "normal" subjects in ex vivo samp les. The techniques used to determine trace element concentrations were pro ton-induced X-ray emission and instrumental neutron activation analysis. Wi th these methods, significant differences are seen between lobes within a h emisphere and between the same lobes of opposing hemispheres for "normal" b rains. The change observed in trace element concentrations may indicate a p ossible alteration in the function of the blood-brain barrier, the effect o f which can be investigated in vivo using the imaging technique of positron emission tomography (PET). A PET study was performed on nine female and ni ne male subjects to determine whether the regional metabolic rate of glucos e (rCMRGlu) varied between hemispheres and sex in the Alzheimer diseased br ain as was seen in the trace element study. Glucose metabolism was measured using [F-18]-fluorodeoxyglucose (F-18-FDG). Hemispherical differences were observed for the frontal, occipital, parietal lobes, and the temporolatera l region in both males and females for rCMRGlu. Variation was also seen bet ween sexes, where the frontal lobe had a lower rCMRGlu in females compared to that of males.