Małgorzata Marjańska

Purpose To understand how macromolecular content varies in the human brain with age in a large cohort of healthy subjects. Methods In‐vivo 1 H‐MR spectra were acquired using ultra‐short TE STEAM at 7T in the posterior cingulate cortex. Macromolecular content was studied in 147 datasets from a cohort ranging in age from 19 to 89 y. Three fitting approaches were used to evaluate the macromolecular content: (1) a macromolecular resonances model developed for this study; (2) LCModel‐simulated macromolecules; and (3) a combination of measured and LCModel‐simulated macromolecules. The effect of age on the macromolecular content was investigated by considering age both as a continuous variable (i.e., linear regressions) and as a categorical variable (i.e., multiple comparisons among sub‐groups obtained by stratifying data according to age by decade). Results While weak age‐related effects were observed for macromolecular peaks at ˜0.9 (MM09), ˜1.2 (MM12), and ˜1.4 (MM14) ppm, moderate to strong effects were observed for peaks at ˜1.7 (MM17), and ˜2.0 (MM20) ppm. Significantly higher MM17 and MM20 content started from 30 to 40 y of age, while for MM09, MM12, and MM14, significantly higher content started from 60 to 70 y of age. Conclusions Our findings provide insights into age‐related differences in macromolecular contents and strengthen the necessity of using age‐matched measured macromolecules during quantification.