AbstractThe characteristics of the31P MR spectra from a large central volume in the brain of 47 healthy adults (aged 25–85 years) were assessed. Spectral parameters were estimated by means of a time‐domain fitting technique. Statistical uncertainties of the estimates were determined by means of the Cramer‐Rao theory and minimized by introducinga prioriknowledge into the fitting procedure. Age‐dependency of the spectral parameters was assessed by means of linear regression. Significant differences between individuals were established for some parameters. A significant age‐dependency (p⩽0.001) of ca 20% over the age range considered was found for the intensity of the phosphocreatine res