Abstract
Knowledge of age-related physiological changes in the human brain is a prerequisite to identify neurodegenerative diseases. Therefore, in this study whole-brain (1)H-MRS was used in combination with quantitative MR imaging to study the effects of normal aging on healthy human brain metabolites and microstructure. Sixty healthy volunteers, 21-70 years of age, were studied. Brain maps of the metabolites NAA, creatine and phosphocreatine, and Cho and the tissue irreversible and reversible transverse relaxation times T2 and T2' were derived from the datasets. The relative metabolite concentrations and the values of relaxation times were measured with ROIs placed within the frontal and parietal WM, centrum semiovale, splenium of the corpus callosum, hand motor area, occipital GM, putamen, thalamus, pons ventral/dorsal, and cerebellar white matter and posterior lobe. Linear regression analysis and Pearson correlation tests were used to analyze the data. Aging resulted in decreased NAA concentrations in the occipital GM, putamen, splenium of the corpus callosum, and pons ventral and decreased creatine and phosphocreatine concentrations in the pons dorsal and putamen. Cho concentrations did not change significantly in selected brain regions. T2 increased in the cerebellar white matter and decreased in the splenium of the corpus callosum with aging, while the T2' decreased in the occipital GM, hand motor area, and putamen, and increased in the splenium of the corpus callosum. Correlations were found between NAA concentrations and T2' in the occipital GM and putamen and between creatine and phosphocreatine concentrations and T2' in the putamen. The effects of normal aging on brain metabolites and microstructure are region-dependent. Correlations between both processes are evident in the gray matter. The obtained data could be used as references for future studies on patients.
Highlights
BACKGROUND AND PURPOSEKnowledge of age-related physiological changes in the human brain is a prerequisite to identify neurodegenerative diseases
Aging resulted in decreased non-subscribers at www.ajnr.org http://dx.doi.org/10.3174/ajnr.A4557 integrity (NAA) concentrations in the occipital GM, putamen, splenium of the corpus callosum, and pons ventral and decreased creatine and phosphocreatine concentrations in the pons dorsal and putamen
T2 increased in the cerebellar white matter and decreased in the splenium of the corpus callosum with aging, while the T2Ј decreased in the occipital GM, hand motor area, and putamen, and increased in the splenium of the corpus callosum
Summary
Brain maps of the metabolites NAA, creatine and phosphocreatine, and Cho and the tissue irreversible and reversible transverse relaxation times T2 and T2Ј were derived from the datasets. Subjects Sixty-eight healthy volunteers were recruited from the local population. Each subject received 2 screening tests (DemTect and the Beck Depression Inventory II) to exclude cognitive or psychiatric impairments.[9,10] Sixty subjects 21–70 years of age (mean age, 44 Ϯ 14 years; 6 men and 6 women in each age group—ie, 21–30 years, group 1; 31– 40 years, group 2; 41–50 years, group 3; 51– 60 years, group 4; and 61–70 years, group 5) were included in the study. Eight subjects were excluded after the screening tests or due to incomplete MR imaging examination findings. The study was approved by local institution review board, and written consent was obtained from all subjects before the examinations
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