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A Mechanism for Stress Damage Uncovered
> 1/23/2008 2:14:23 PM

Chronic stress has been linked to a bevy of physical and mental problems. While this link is certain, the mechanism through which stress does its damage is not fully understood. Researchers from the Yale School of Medicine just discovered one part of the mechanism, and they offer that part in this month�s Proceedings of the National Academy of Sciences as a stepping stone towards future treatments for the corrosions of stress.

The Yale researchers focused on the cytokine IL-1�, the presence of which increases in animals when stressed. IL-1� was first known as a mediator of the immune response to infection, with its most dramatic effect being fevers. It achieves this effect by resetting the hypothalamus thermoregulatory center, but recent work has suggested that IL-1� has other important effects on the brain.

Stressed mice produce more IL-1� in many regions of the brain, including the hippocampus, pituitary, hypothalamus, and adrenal system. In the hippocampus, neural growth is significantly inhibited, compromising the brain's ability to adapt to new challenges presented by the environment. To confirm that the cytokine is responsible, the Yale researchers found that neural regeneration resumed when they blocked the IL-1� receptor.

Doctors Malberg and Manev, along with a number of other scientists, have suggested that antidepressants aid the recovery process by boosting neurogenesis. This is plausible, as antidepressants have been prevented from working by suppressing neurogenesis with irradiation that kills only newly forming neurons. If this is true, then the Yale researchers have finally uncovered the mechanism by which stress impairs the brain and leads to depression and possible a number of other disorders.

Stress is an emergency tactic, meant to get us through brief challenges by sacrificing long-term health for short-term boosts. If this emergency button is left on for too long, it can cause our bodies and minds to break down. This new study illuminates one way that this breakdown can occur. While it makes sense to save energy during an emergency by temporarily halting neurogenesis, a permanent hold on neurogenesis will deprive the brain of the adaptive ability that it needs in order to handle the ever-changing demands of the world. Now that this balance and the ways that it can be disturbed are understood, scientists may be able to develop more focused medications to protect against damage from stress.

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