Proton magnetic resonance spectroscopy in frontotemporal dementia

This study of frontotemporal dementia (FTD) was carried out to determine whether MR spectroscopy can provide an in vivo marker for the neuronal loss and gliosis that occur in this condition. We compared spectra in frontal and temporal regions known to be affected early in the course of the disease with spectra in the parietal lobe that is spared until late stages of FTD. We were interested in the relative concentrations of two compounds, NAA (a marker of neuronal integrity) and mI (a marker of gliosis), expressed as ratios to creatine (a relatively stable brain constituent). MR spectroscopy was performed on the temporal, parietal, and anterior cingulate cortices of five patients with the established semantic dementia form of FTD, two patients with the frontal form of FTD and 13 age matched controls. Structural MRI and neuropsychometry were also performed. Patients with FTD had reduced NAA/Cr in frontal and temporal, but not parietal lobes. The two patients with the frontal form of FTD had increased mI/Cr in their cingulate cortices. These data show for the first time that MR spectroscopy can reveal regionally selective abnormalities in patients with FTD. This opens up the possibility of using MR spectroscopy as a clinical tool to identify earlier presentations of the condition.