Age-related differences in metabolites in the posterior cingulate cortex and hippocampus of normal ageing brain: A 1H-MRS study

ObjectiveTo study age-related metabolic changes in N-acetylaspartate (NAA), total creatine (tCr), choline (Cho) and myo-inositol (Ins).Materials and methodsProton magnetic resonance spectroscopy (1H-MRS) was performed in the posterior cingulate cortex (PCC) and the left hippocampus (HC) of 90 healthy subjects (42 women and 48 men aged 18–76 years, mean ± SD, 48.4 ± 16.8 years). Both metabolite ratios and absolute metabolite concentrations were evaluated. Analysis of covariance (ANCOVA) and linear regression were used for statistical analysis.ResultsMetabolite ratios Ins/tCr and Ins/H2O were found significantly increased with age in the PCC (P < 0.05 and P ≤ 0.001, respectively), and in the HC (P < 0.01 for both). An increased tCr/H2O was only observed in the PCC (P < 0.01). Following absolute quantification based on the internal water signal, significantly increased concentrations of Ins and tCr in the PCC confirmed the relative findings (P < 0.01 for both).ConclusionAge-related increases of tCr and Ins are found in the PCC, whereas this holds only true for Ins in the HC, indicating possible gliosis in the ageing brain. No age-dependent NAA decreases were observed in the PCC nor the HC. The 1H-MRS results in these specific brain regions can be important to differentiate normal ageing from age-related pathologies such as mild cognitive impairment (MCI) and Alzheimer's disease.