Cell Density Remains Constant as Brain Shrinks with Age

New, ultra-high-field magnetic resonance images (MRI) of the brain provide the most detailed images to date to show that while the brain shrinks with age, brain cell density remains constant. The study of cognitively normal young and old adults, published in the journal NMR in Biomedicine, presents the first evidence that in normal aging, cell density is preserved throughout the brain, not just in specific regions. The findings also suggest that the maintenance of brain cell density may protect against cognitive impairment as the brain gradually shrinks in normal aging. The study’s images were made by a powerful 9.4-Tesla MRI, the first of its kind for human imaging and currently approved only for research. Researchers scanned the brains of 49 cognitively normal adults ranging in age from 21 to 80; all were without major medical, neurological or psychiatric disease and scored within the normal range for mental status. The 9.4 Tesla MRI measures sodium ions, which are less concentrated by several orders of magnitude than the fat and water molecules detected with standard MRI. With sodium concentrations in the brain reflecting neuron density, areas of low sodium concentration indicate lots of neurons packed tightly together, while higher sodium concentration can indicate more space between cells — or the loss of cells, as in the case of neurodegenerative diseases. “We can use the 9.4 T to look at brain cell loss in real time in patients experiencing stroke, or to see whether chemotherapy for brain tumors is working in higher resolution that is just not available using the current 3 T clinical scanners,” said the lead author. To learn more about this study, click here.