Purpose: To detect regional differences in accompanying metabolic changes, 1H-Magnetic Resonance Spectroscopic Imaging (MRSI) was performed in 16 patients with Alzheimer's disease (AD); the clinical diagnosis was based upon DSM-III-R and NINCDS-ADRDA guidelines.
Methods: In the hippocampal region metabolic maps of the local distribution of N-acetylaspartate (NAA), choline (Cho), creatine compounds (P(Cr)) and lactate were determined. Ratios of Cho/NAA, (P)Cr/NAA and Cho/(P)Cr calculated from selected hippocampal spectra were compared to those from healthy volunteers (n = 17).
Results: AD patients demonstrated an increase of Cho/NAA and (P)Cr/NAA ratios caused by increased choline compounds and decreased NAA. These alterations were observed in 11/12 cases in the hippocampal and in 7/12 in the temporo-occipital region. Hippocampal Cho/NAA ratios (0.56 +/- 0.19) were significantly elevated compared with controls (0.33 +/- 0.04; p < 0.0001).
Conclusion: The observed elevation of choline compounds in the hippocampus supports the hypothesis that alterations in the cholinergic system play an important role in Alzheimer's disease. The observed reduction of NAA is due to neuronal degeneration.