Figure 5.
Volumetric measurements of cortical gray matter, cortical white matter, cortical CSF and ventricular CSF from 73 healthy men, aged 21 to 70 years old plotted as a function of age.  The regression line is a weighted constrained quadratic function.  Weighting was used to take into account the heteroscedasticity (increased variance in older age) of the data.  Brain measures (expressed in cc) were first regressed against an estimate of head size volume.  Residual values were then calculated for each subject by subtracting their predicted score for each ROI, based on head size, from the observed score.  Cortical gray matter volume showed an average decrease of 0.7 cc per year, whereas cortical white matter remained stable oacross the five decades.  Cortical CSF increased 0.6 cc per year, and ventricular CSF 0.3 cc per year.

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published 2000