After Julia had a minor stroke, she was thankful for receiving rapid treatment and recovering well. But she did notice an unexpected aftereffect as she returned to normal activities. In meetings at work, she was unable to follow the back and forth among attendees. And when she was asked for her own opinions, she found she hadn't grasped well enough what had been discussed to participate. At home, if she was working on a task like cooking dinner, she realized she couldn't easily carry on a conversation with her husband.

So at her next visit with her doctor, she mentioned her symptoms--and found out she was not alone.

Julia is experiencing poststroke acute dysexecutive syndrome (PSADES), a cognitive dysfunction that people commonly experience after even minor strokes. The condition becomes evident soon after the stroke occurs, and while it correlates to having dead tissue lesion(s) in the brain left behind by the stroke, it does not seem to be related to the location of the lesion(s). Fortunately, PSADES gradually improves in the months after recovery. But what has been going on inside the brain during this time?
Stroke patients have reported these cognitive difficulties to their doctors for a long time. Until now, the evidence of this problem has mostly been anecdotal. A new study by University of Maryland, Johns Hopkins University and New York University researchers for the first time provides measurable physical evidence of diminished neural processing within the brain after a stroke. It suggests that PSADES is the result of a global connectivity dysfunction. The paper, "Poststroke acute dysexecutive syndrome, a disorder resulting from minor stroke due to disruption of network dynamics," has just been published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

The paper was written by the University of Maryland's Professor Jonathan Simon (Electrical and Computer Engineering/Biology/Institute for Systems Research), his former postdoctoral researcher Christian Brodbeck, now a visiting assistant professor at the University of Connecticut, and UMD Ph.D. student Joshua Kulasingham; the Johns Hopkins School of Medicine's Associate Professor Elisabeth Marsh, Professor Rafael Llinas and Dania Mallick, all of the Department of Neurology; and NYU Grossman School of Medicine Research Professor Rodolfo Llinas. Marsh is the lead author.

"We tend to think that certain parts of the brain are responsible for specific functions, but in reality you need your entire brain to think clearly and complete tasks," Marsh says. "In this study we show how a small lesion anywhere can disrupt the cognitive network and result in a global dysfunction."

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