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1H Magnetic Resonance Spectroscopy Assessment of the Effects of Rivastigmine on Patients with moderate Alzheimer Disease
Alvarado Arturo, Figueroa Yelena, Mendoza Alberto, Ortíz Hodalitz, Itriago Valentina, Alvarado Mariangela
Abstract
This study was designed to perform MRS of the Temporal Lobe (TL) and Frontal Lobe (FL) to assess brain metabolic changes that result from treating moderate-AD (AD) patients with Rivastigmine. Twenty AD patients were studied after obtaining both their informed consent and their caregivers'. They were divided into two groups of ten patients each one: Rivastigmine Group (RG) and Control Group (CG), and matched by age and sex. RG took Rivastigmine during 16 weeks (1.5 mg/day the first two weeks, 3 mg/day the following six weeks, and 4.5 mg/day the last eight weeks). CG took placebo during 16 weeks. Mini-Mental State Examination (MMSE), Magnetic Resonance Imaging (MRI), and MRS were performed before and after the 16-week study. MRI and MRS were carried out on a 1.5 Tesla system (Sonata, Siemens Erlangen®). Single Voxel Spectroscopy (1.8 cm x 1.8 cm x 1.8 cm = 5.83 cm3) were acquired with a 90°-180°-180° Spin-Echo Sequence (TR=1500 msec, TE=30 msec,192 averaged acquisitions). N-Acetylaspartate (NAA), Creatine (Cr), Choline (Cho), and myo-inositol (mI) intensity signals were detected and NAA/Cr, mI/Cr, Cho/Cr and NAA/mI ratios were calculated. Analysis of Variance was applied to the results. Tukey test was used for comparisons among ratio means with Bonferroni correction for small samples. Spearman rank correlation coefficients were calculated for both MMSE scores and measured metabolite ratios. A significant increase (p<0.05) in the NAA/Cr ratio for the Right FL and a significant increase (p<0.05) in the NAA/mI ratio for the Left TL were found in the RG after 16 weeks of Rivastigmine treatment. These changes were correlated to the RG patients' improvement in cognitive mental status that was uncovered through the MMSE's AD Assessment Scale Scores. No significant changes were found in the CG after 16 weeks of placebo treatment. MRS may provide a useful tool for monitoring the therapeutic response of AD patients to Rivastigmine. The link between MRS-based Rivastigmine monitoring and the MMSE's AD Assessment Scale Scores may also provide a fertile ground for developing a Rivastigmine-based therapy and predicting its efficacy to improve AD patients' cognitive status.
Keywords
1H Magnetic Resonance Spectroscopy (MRS), Alzheimer's Disease (AD), Mini Mental State Examination (MMSE), Rivastigmine
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