Posterior cingulate metabolic changes in frontotemporal lobar degeneration detected by magnetic resonance spectroscopy.

Differences in prognosis and symptomatic treatment have highlighted the importance of the differential diagnosis of frontotemporal lobar degeneration (FTLD) and other dementias, but the variable clinical features make diagnosis difficult. We studied metabolic changes using multivoxel proton magnetic resonance spectroscopy (MRS) in regions of FTLD, including the posterior cingulate gyrus, which is also the area most affected by Alzheimer's disease (AD) in the early stages. We examined six patients with FTLD, six with presumed AD, and five healthy volunteers using repetition and echo times of 2000 and 135 ms. We analysed peak ratios of choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) from frontal and temporoparietal regions, basal ganglia, and posterior cingulate gyrus in both hemispheres. A decreased NAA/Cr ratio was observed in the posterior cingulate gyri in presumed AD (right: 1.56+/-0.44, P =0.011; left: 1.46+/-0.25, P =0.008) and FTD (right: 1.47+/-0.40, P =0.005; left: 1.36+/-0.32, P =0.002). No statistically significant changes in Cho/Cr were identified in the posterior cingulate gyri in presumed AD or FTLD, and no differences were observed in peak ratios in other regions. Decreased NAA may reflect neuronal activity in the posterior cingulate gyrus, and this study may contribute to insights into the pathophysiology of FTLD.