My mother and her siblings experienced high levels of abusive-type stress growing up. They all suffer from depression. She has little observable stress now, but she is still depressed. What’s the deal?The “deal” may be that studies at the Icahn School of Medicine at Mount Sinai have shown that stress early in life increases one’s susceptibility to additional stress in adulthood. Stress, is of course, an epigenetic factor involving lifestyle—as opposed to genetics involving genes and chromosomes. The epigenetic modification, triggered by early-life stress, apparently impacts an important part of the Brain Reward System known as the nucleus accumbens, an essential component of the brain's reward system. It appears a specific enzyme associated with medium spiny neurons of the nucleus accumbens bidirectionally controls stress susceptibility. More enzyme equates with increased stress susceptibility. Less enzyme is linked with decreased stress susceptibility. More tomorrow.