Stress Test is a series about the science behind our busy lives and how stress affects our bodies. The biweekly column uncovers the latest research and explains how to put it to use in a practical way. Look for the science behind epigenetic markers of stress, mindfulness, meditation and deep brain stimulation.
We know stress is bad for us and that is affects our minds and bodies. But how exactly does that happen? Researchers are looking at a new angle of genetics, called epigenetics, which essentially shows how our environments change our genes. Specifically, chemical changes tell our DNA to switch genes on and off in response to stress to better regulate body functions. But studies are showing that chronic stress can lead to harmful changes such as depression, obesity and cancer.
“If you think of the stress system as preparing you for fight or flight, you might imagine that these epigenetic changes might prepare you to fight harder or flee faster the next time you encounter something stressful,” said James B. Potash of the Johns Hopkins University School of Medicine, who was one of the first U.S. scientists to begin researching the effect of stress hormones on epigenetics more than a decade ago. Potash and colleagues are now delving into the latest promising epigenetic research regarding depression, bipolar disorder and post-traumatic stress disorder.
In February 2017 alone, several studies pointed to the growing knowledge about stress and epigenetic changes that we didn’t realize before. For one, can you believe that fetuses know when their moms experience toxic stress related to domestic violence, homelessness or depression? And in men, epigenetic changes can affect sperm, even 10 years down the road. Stress can also impact tumor growth and how cancer cells spread throughout the body.
At the same time, scientists are finding ways to play an active role in epigenetics by learning how to turn genes on and off in the brain. The most recent wave of research is doing this through optogenetics, or using light-sensitive proteins and enzymes with a blue light to tell stem cells in the brain what to do. Though it only works with a few specific genes right now, optogenetics could mean new therapies for cancer or genetic diseases in the future.
The latest research tells us a few other findings about our epigenetics and what happens when stress changes our genes:
Epigenetic studies show—now more than ever—our brains (and the neurons, dendrites and synapses inside) adapt to our experiences. This applies to both acute and chronic stress and can mold the way we see and react to the world. Several studies say that mood and psychiatric disorders can stem from prolonged stress that creates permanent alterations in neural circuits. Scientists have noted links to depression, anxiety, PTSD and possibly even addiction and schizophrenia.
Although nutrition and exercise play a big role, genes and environment also influence obesity, and the increasing incidence of it in Western society. Stress puts the body on alert and produces cortisol as a hormone to combat anxiety, but we often have too much of it, which leads to major inflammation. We’re also soothing hectic schedules and busy minds by consuming carbs, sweets and treats associated with chronic inflammation. Last year, a group of researchers found that mindfulness meditation was linked to reduced expression of three genes that control inflammatory pathways, decreased expression of two pro-inflammatory genes, and prompted faster cortisol recovery.
Since stress signals to our genes to toggle certain body processes off and on, it makes sense that cells malfunction and sometimes mutate. Tumors form, and certain epigenetic changes can make them spread even faster. Stress also affects telomeres, which are genetic particles that cap off the ends of chromosomes. Shorter telomeres have been connected to the development of bladder, bone, lung and kidney cancer, as well as diabetes, heart disease and high psychological stress. Small studies with cancer patients at the University of California in San Francisco have begun to show that cancer patients who take up daily meditation, breathing, walking and yoga exercises have decreased gene expression associated with cancer.
At Emory University in Atlanta, scientists exposed mice to the smell of cherry blossoms when they shocked them. Soon enough, the smell triggered shuddering without the shock. The surprising part was that offspring also shuddered at the smell, even though they were never shocked. Due to previous studies, researchers thought that epigenetic changes were “scrubbed” when DNA was passed from parents to kids, but that only happens sometimes. Researchers are now finding that stress, especially psychological disorders, can pass through and affect kids.
Since the mice study, scientists have seen epigenetic changes pass through humans, too. In a study of Holocaust survivors, New York researchers found that survivors had gene changes related to the traumatic events they experienced and witnessed during World War II. These changes aren’t seen in any Jewish people who lived outside of Europe during that time. The shocking revelation, the scientists found, was that the survivors’ children had these same epigenetic changes. In fact, they were known to have even higher rates of stress disorders.
Although epigenetic studies seem negative and upsetting, especially when it comes to the effects of stress, the good news is that many epigenetic changes are seen as reversible. Teams of researchers around the country are looking at ways to stop or roll back epigenetic markers that lead to cancer, Alzheimer’s disease or diabetes. In fact, a couple of drugs are being tested that help the genes to go back to their original state.
And no surprise here — other new studies are showing that a healthy diet, regular exercise, meditation and plenty of sleep help stress and epigenetic changes as well.
Images: Andy Leppard, Flickr, CC-BY and Caroline Davis, Flickr, CC-BY
Carolyn Crist is a freelance health and science journalist for regional and national publications. She writes the Escape Artist column for Paste Travel, On the Mind column for Paste Science and Stress Test column for Paste Health.