How do we differentiate between normal cognitive aging and diseases that affect the brain?
Such is the charge of Dr. Scott A. Small, director of the Alzheimer’s Disease Research Center at Columbia University Irving Medical Center and the Boris and Rose Katz Professor of Neurology. Through the use of cutting-edge neuroimaging technology, Dr. Small is working to identify the causes of Alzheimer’s and determine precisely how the disease affects the brain. His primary target? The hippocampus, a memory structure that often experiences shrinkage in a patient with Alzheimer’s disease.
“For a while, there was a debate about whether Alzheimer’s and aging are one in the same,” says Dr. Small. “Through a decade of work, we were able to dissociate regions of the hippocampus that were most linked to aging versus those that were most linked to Alzheimer’s.”
Using a method known as high-resolution functional magnetic resonance imaging (fMRI), Dr. Small and his fellow researchers learned critical information about the structure of the hippocampus. Within the hippocampus, there are several regions and a circuit of nodes. Both aging and early-stage Alzheimer’s can impact the circuit of nodes, which initially made it difficult for scientists to distinguish between the two.
By comparing the fMRI scans of mice and humans, Dr. Small’s team has come to better understand how the hippocampus functions during normal associative memory, as well as how it fails during aging and during Alzheimer’s. The team determined that there are regions of the hippocampus that are more likely to be linked with either age-related memory loss or early Alzheimer’s, respectively.
With this in mind, Dr. Small and his team are trying to better understand the molecular mechanisms behind both age-related memory loss, together with Dr. Eric Kandel, and in Alzheimer’s, together with Dr. Richard Mayeux.
“More and more of our patients are simply healthy elders who say, ‘I’ve noticed some memory loss. Is it early Alzheimer’s or normal aging?’” Dr. Small says.