Stress Reveals Connections Between the Brain and the Blood

It is well known that chronic stress, especially if it is unpredictable, promotes inflammation. To learn more, researchers conducted a series of experiments in mice and 29 medical residents.

The residents self-reported higher stress levels and had higher peripheral neutrophil, monocyte, and lymphocyte counts during their intensive care rotation than at baseline.

Compared with nonstressed controls, mice stressed for 3 weeks had similar blood-count findings as humans; these increases were associated with increased proliferation of bone-marrow stem cells that were differentiating into white cells. Stem cell proliferation was linked to norepinephrine activity in sympathetic nerves innervating blood vessels in bone marrow, apparently via a β3-adre…