Brain’s Dumped DNA May Lead to Stress, Depression

Brain’s Dumped DNA May Lead to Stress, Depression

Knvul Sheikh

Humans and other mammals react to stressful situations through a series of well-orchestrated evolutionary adaptations. When faced with a predator looking for its next meal, or with worry of losing a job, our bodies release a cascade of stress hormones. Our heart rate spikes, breath quickens, muscles tense up and beads of sweat appear.

This so-called “fight-or-flight” response served our ancestors well, but its continual activation in our modern-day lives comes with a cost. Scientists are starting to realize stress often exacerbates several diseases, including depression, diabetes, cardiovascular disease, HIV/AIDS and asthma. One theory is hoping to explain the link between stress and such widespread havoc by laying the blame on an unexpected source—the microscopic powerhouses inside each cell.

Each of our cells contains hundreds of small bean-shaped mitochondria — subcellular structures, or organelles, that provide the energy needed for normal functioning. Mitochondria have their own circular genome with 37 genes. We inherit this mitochondrial DNA only from our mothers, so the makeup of the DNA’s code stays relatively consistent from one generation to the next.

But our fight-or-flight response places extreme demands on the mitochondria...