Stress is your way of life, you’re juggling tasks like a circus act and you think you’re operating at peak capacity? Think again, says another study on the effect of stress on the brain — this one from New York’s Weill Medical College at Cornell and Rockefeller University and published in the journal Proceedings of the National Academy of Sciences.

For the study, 20 medical students about to take board exams — all of them stressed — were examined via functional MRI, which measures flow of blood in the brain, as they performed different tasks. Researchers compared the performance and brain function of the medical students with a group of similarly aged subjects who were not stressed. When put to two tasks that measured the ability to shift attention and then shift back, the medical students performed far worse than the relaxed group.

The brains of the stressed gave the inside story: During the attention-shifting task, activity in their prefrontal cortices — the seat of such functions as attention, task-planning and judgment — was far lower than that of the nonstressed. And connectivity between that area and other regions of the brain with which it works to translate thought into action was diminished, too.

A month after the exams were over, the med students repeated the tasks. Their ordeal and a period of relaxation behind them, their brain scans looked similar to those of the control group.