The Aging Brain

Muddle in the Middle
The Aging Brain
by Katharine Dunn

Neuroscientists have long used damaged brains as a way to understand normal brain functions. But doing the opposite also works. A group of researchers at Harvard recently looked at the effects of aging on healthy people’s brains and found that as we get older, communication between different brain regions breaks down. This discovery could eventually help scientists better characterize and detect neurodegenerative diseases, including Alzheimer’s, which affects more than 5 million Americans.


The younger brain, below, shows more synchronized activity than the older brain, above.

Until recently, most scientists looking at the aging brain focused on individual regions, especially those in the frontal lobe, which may shrink or lose activity even in the absence of disease, says Jessica Andrews-Hanna, a doctoral student in psychology at Harvard’s Center for Brain Science and the lead author on the group’s paper (published last December in the journal Neuron). Though other investigators had hypothesized that disconnections might occur in the ebb and flow of signals between regions, it wasn’t easy to measure this until the introduction in the early 1990s of functional magnetic resonance imaging (fMRI), a scanning technique that measures blood flow.

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