While the brain shrinks with age, cell density remains preserved throughout the brain, not just in specific regions, new ultra-high-field magnetic resonance images (MRI) by researchers at the University of Illinois at Chicago show.
The findings also suggest that the maintenance of brain cell density may protect against cognitive impairment as the brain gradually shrinks in normal aging.
Neuroscientists have long known that the brain shrinks with age, but for a long time they thought the loss in volume was associated with a loss of brain cells. That was disproven by studies that showed it is the neurons themselves that shrink while the number of cells remains the same in normal older adults.
The images were created by a powerful 9.4-Tesla MRI, the first of its kind for human imaging, the study said.
The 9.4 T magnetic field is more than three times stronger than that of a typical MRI machine in a doctor's office and is currently approved only for research.
"The information provided by these 9.4-Tesla scans may be very useful in helping us detect tiny losses of brain cells and the reduction in cell density that characterises the early stages of neurodegenerative diseases that can take decades to develop before symptoms appear, like Alzheimer's disease," said lead author Keith Thulborn, professor at the University of Illinois at Chicago.
"If we can identify when Alzheimer's pathology starts, the efficacy of new drugs or other interventions to slow or prevent Alzheimer's disease can be tested and monitored when the disease starts, instead of after it's developed for 20 or 30 years and becomes clinically apparent," Thulborn noted.
The study that involved scanning the brains of 49 cognitively normal adults ranging in age from 21 to 80 was published in the journal NMR in Biomedicine.
Thulborn thinks the ultra-high-field scanners eventually will be approved for clinical use.
"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," he said.
