Stress breeds depression. Anecdotally, we all know that's the case, but scientifically speaking it's been a hypothesis that has until now remained unproven. A new study, however, reveals that chronic stress affects us at the genetic level, in turn creating very real brain changes associated with depression.
A team of researchers from Yale University has been studying how rats react to chronic, unpredictable stress. To do that, they subjected a group of rats to food and play deprivation, isolated them from other rodents, and switched around their day-night cyles for three weeks. Eventually, the rats were left with little interest in food or enjoying a sweetened drink, and didn't swim when placed in water—all signs of rodent depressions.
Then, the researchers focused on their gene activity. In particular, the team found that the neuritin gene—also present in humans—was much less active compared to the control population. Part of the depressed group of rodents responded well to anti-depressants, quickly recovering. The same, however, was also true if the researchers stimulated production of neuritin by injecting the rats with a virus that triggered the gene's expression.
Perhaps most interesting is the fact that stimulating the production of neuritin also protected the rats from structural brain changes seen in mood disorders—which can't be said of all anti-depressants. Previous research has shown that depression causes shrinking of the hippocampus and general decline in neuron health, both of which were prevented by the promotion of neuritin production. The findings are published in PNAS.
The results add serious weight to the idea that stress can directly bring about depression. Perhaps most importantly, it offers hope for the production of future anti-depressants. Currently, only 30 per cent of people with stress-related mood disorders achieve full recovery when using existing anti-depressants—and a neuritin-based approach could help boost that figure significantly. [PNAS via Science]
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