Chronic Stress Disrupts the Brain’s Ability to Shift Attention
February 10, 2009
"Ordinary chronic stress can impair our ability to shift attention flexibly, according to a recent study of stressed-out medical students. The study found that stress achieves this temporary remodeling of the brain by reducing the connectivity of an attention-regulating area of the prefrontal cortex.
“It’s reassuring that this attention-shifting deficit seems to go away after stress is reduced, but such deficits are similar to what we see in a number of stress-related psychiatric disorders, so we need to know more about it,” says the study’s first author, Conor Liston, a neuroscientist and a psychiatry resident at New York-Presbyterian Hospital. The study was released Jan. 12 on the Proceedings of the National Academy of Science Web site.
“This study is the first to show how this common behavioral experience in people may relate to weaker brain network connections,” says Amy Arnsten, a neuroscientist at Yale University who has done work in this area. “Importantly, the effects of stress were fully reversible, similar to those seen in animals.”
The article goes on to say:
"This loss of flexibility is a symptom of anxiety disorders and depression; people with these disorders typically find it hard to shift their focus away from fearful or otherwise negative thoughts. Evidence suggests that drug addiction, too, empowers limbic craving activity and at the same time weakens the inhibitory influence of the dorsolateral prefrontal cortex.
Stress is known to play a role in all of these conditions. Although the mechanisms by which it boosts some regions and impairs others are not yet clear, Arnsten and colleagues have shown in animal experiments that, for example, stressful conditions can raise levels of the neurotransmitters norepinephrine and dopamine in prefrontal regions. These raised levels in turn may alter the sensitivity of the neurons in those regions, effectively reducing their influence over behavior.
Whether chronic-stress-induced changes in prefrontal neurotransmitter levels eventually lead to actual dendritic shrinkage remains to be seen. “This is still a new area that we don’t know much about,” says Liston. “But the ultimate goal is to design targeted interventions aimed at exploiting the finding that a stress effect like this is reversible.”
To read the full Article from "The Dana Foundation" Click here