What Role Does Early Life Stress Play in Depression?U.S.News & World Report
David Levine September 12, 2017
Among the many risk factors for depression, such as family history, being female and going through unsettling life changes, one that stands out goes by the benign clinical description "adverse childhood experiences." ACE for short, an adverse childhood experience is anything but benign. The Substance Abuse and Mental Health Services Administration defines them as "stressful or traumatic events, including abuse and neglect," and states that they may "include household dysfunction such as witnessing domestic violence or growing up with family members who have substance abuse disorders." SAMHSA adds parental separation or divorce, household mental illness and incarcerated family members to the list of unlucky ACEs.
Such early life stressors are clearly linked to future mental health issues, including depression. (They predict a host of physical problems, as well, including higher risk of chronic medical problems like diabetes and cardiovascular disease, sexually transmitted disease and early death.) The Diagnostic and Statistical Manual of Mental Disorders, or DSM-5, the guide used by health care professionals in the U. S. to diagnose mental disorders, states unequivocally that, "Adverse childhood experiences, particularly when there are multiple experiences of diverse types, constitute a set of potent risk factors for major depressive disorder." And an important 2004 study of almost 10,000 subjects concluded that, "exposure to ACEs is associated with increased risk of depressive disorders up to decades after their occurrence."
Stress Alters Brain Function
While the data are clear that early stress sets up some individuals for later problems, it's less clear why this is so. "It is not known exactly how early or chronic stress affects the brain," says Dr. Gene Beresin, executive director of the Clay Center for Young Healthy Minds at Massachusetts General Hospital and a professor of psychiatry at Harvard Medical School. Some research provides evidence that childhood abuse likely results in dysregulation of the parts of the brain that modulate hormonal balance. "It may be that overstimulation of the brain's signals to the adrenal glands foster greater fight-or-flight responses, and this impairs the proper balance of chemicals in the brain that prepare the individual to react to life-threatening situations," he says. "This imbalance of hormones and neurotransmitters may well result in biochemical, functional and structural changes in the brain. There is evidence from brain imaging studies that certain regions of the brain are lower in volume following child maltreatment. How these brain regions are affected is not known."
There is other evidence that chronic and prolonged stress causes a "toxic stress response" that may disrupt brain structure and increase risks for post-traumatic stress disorders and information processing, Beresin adds. Many developmental researchers and clinicians have noted that healthy brain structure and function, as indicated by the delicate balance between chemicals in the brain, hormones and developing brain structures, "requires consistency in the environment, and [are] particularly grounded in a secure attachment to parental figures and other important adults in the child's life," he says.
A June 2017 study conducted on mice at the Icahn School of Medicine at Mount Sinai may have found the link between early life stressors and neurobiological changes. The study looked at epigenetics: How changes in the action of genes are in part driven by environmental factors like nutrition, exercise, pollution -- and stress. The research found that early life stress generates a lifelong susceptibility to future stress changes in the programming in a reward region of the brain that is linked to mood and depression.
"Our work identifies a molecular basis for stress during a sensitive developmental window that programs a mouse's response to stress in adulthood," Catherine Peña, lead investigator of the study, said in a release. "We discovered that disrupting maternal care of mice produces changes in levels of hundreds of genes ... that primes this brain region to be in a depression-like state, even before we detect behavioral changes. Essentially, this brain region encodes a lifelong, latent susceptibility to depression that is revealed only after encountering additional stress."
Stress Alone Is Not the Problem
It's hard to find a child who hasn't had some kind of stress. In fact, a landmark ACE study of more than 17,000 adults, conducted by the Centers for Disease Control and Prevention from 1995 to 1997, in partnership with Kaiser Permanente, found that 28 percent of study participants reported physical abuse and 21 percent reported sexual abuse as children. Many also reported experiencing a divorce or parental separation, or having a parent with a mental and/or substance use disorder. Almost 40 percent of the sample reported two or more ACEs, and 12.5 percent experienced four or more.
But not every one of those children developed a mental illness. "If you had a million early, extremely difficult experiences, and you're now 14 and unhappy, you might have clinical depression, or you might be unhappy because your life has been extremely difficult," says Dr. John T. Walkup, director of the Division of Child and Adolescent Psychiatry at Weill Cornell Medicine and New York-Presbyterian Hospital. "When life events have been severe, we often can't differentiate the differences" between clinical depression and general unhappiness.
It's the combination of adverse life experiences with a predisposition to mental health issues that has resulted in an increased prevalence of depression among young people, he says. "About 20 percent of kids will have a mental health problem before they finish high school," Walkup says. But, for those who develop depression, "is that really about adverse events or is it about the general risk of depression?
As Beresin notes, "stress is not itself damaging or results in poor outcomes. Naturally the younger the child, the more important it is that parents and caregivers provide ongoing protection from severe or prolonged stress. However, children need to progressively learn how to cope with stress." And most of them do.
But many do not. Some kids -- and adults -- are simply more prone to reacting badly to stress. "It is imperative to understand that a response to stress is complex and involves the child and her or his innate vulnerabilities, the parents or caregivers and what they provide for the child, and the environment, including neighborhood, school and spiritual community," Beresin says. "All three domains need to be understood to determine a child's acute or chronic reactions to stress."
The best way to prevent future mental health issues is to provide stable, consistent, nurturing relationships for children, Beresin says, and for that, parents must have their own means for stress reduction. "It is much like what we hear from flight attendants -- 'put the life mask on yourself first, and then help the child next to you,'" he says. "In this light, parents need supportive relationships and community, as well as means to control their own stress. A parent cannot provide support for a child if the parent is unable to cope with stress."
The DSM-5 states that, "Early recognition of childhood abuse and appropriate intervention may thus play an important role in the prevention of depressive disorders throughout the life span." Walkup puts it more directly: "In the mental health field we advocate for understanding, appropriate care and nurturing for children so they have the best chance to reach their optimum potential."
https://www.yahoo.com/news/role-does-early-life-stress-play-depression-144654527.html
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