Depression is a prevalent disorder whose origins (like those of so many other mental diseases) are nonetheless shrouded in mystery. A new study published in Nature has identified one potential cause of depression. The study involved mice whose hippocampi were unable to generate neurons.
The hippocampus is a portion of the brain that is particularly vulnerable to stress, as a Booster Shots blog entry by Karen Kaplan explains. Mice whose hippocampi couldn't grow new neurons acted like other mice during normal conditions. However, under stressful conditions, these mice were unequipped to handle the stress and became depressed, exhibiting some of the hallmark symptoms of mouse depression (e.g., losing their taste for sugar water). Their stress-hormone levels remained high for much longer than those of normal mice exposed to the same stressors.
These findings are consistent with past research showing that antidepressants trigger neuron growth in the hippocampus, which may be partially responsible for their depression-easing effects. A better understanding of the delicate relationship between stress and depression is an important tool for producing more effective treatments.