Columbia University Medical Center

How PTSD Impairs Learning and Memory

The highlighted area shows the hippocampus, part of brain’s limbic system – a primitive part of the brain involved in emotions, learning and the formation of memories.

Most people associate post- traumatic stress disorder with anxiety, anger, and, at its worst, suicide. But one of the most pervasive symptoms of PTSD is not directly related to emotions at all: individuals suffering from a stress-related disorder experience cognitive difficulties ranging from memory loss to an impaired ability to learn new things.

One of the most crucial cognitive deficits of PTSD involves how we handle new experiences and fold them into the fabric of memory. It’s called pattern separation—literally, the brain’s way of separating similar experiences, places, and events.

“Even though I may remember 9/11, when I see an airplane over New York City, I am able to recognize that it’s a different situation and process it accordingly. Someone in the same situation who has PTSD may re-experience the traumatic events of 9/11 and have a panic attack,” said Rene Hen, a Columbia University Medical Center researcher. Dr. Hen recently led a study showing that boosting the number of neurons in the adult mouse brain led to improved pattern separation.

The area of the brain that Hen targeted in his study—the hippocampus—may be where the seemingly disparate areas of learning and mood come together. Both Hen’s research and a new study led by Dr. Andrew R Marks may contribute to potential treatment for PTSD and related anxiety disorders.

“This research may also help explain a bit of a mystery in the field, which is how the hippocampus can be involved with both cognition—its classic function—and mood and anxiety-related functions. Perhaps the fact that pattern separation affects both the cognitive and mood domains is the beginning of an answer to that paradox,” said Dr. Hen.

–Michele Hoos

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