The Sensitivity Gene – Donna Jackson Nakazawa.

Roughly 15 percent of the general population possesses a variant of a behavioral gene called 5-HTTLPR, which regulates the neurotransmitter serotonin. Serotonin influences our ability to rebound from emotional trauma and distress. This Sensitivity Gene exists in three variants. People with the short/short variant tend to be highly sensitive to whatever they meet up with in their day-to-day life.

People with this Sensitivity Gene variant who experience adversity when growing up face the greatest likelihood of suffering from depression in adulthood.

Having supportive, responsive relationships with caring adults as early in life as possible makes a profound difference.

A particular characteristic that is typical of centenarians, is that they manage life stress very well. Even those centenarians who have had really very difficult, and even traumatic lives of extreme adversity, including holocaust survivors, seem to be able to “roll with the punches . . . accept their losses, grieve them and then move on. They bounce back.

Most kids who experience chronic stress and trauma don’t have the tools or maturity to regain their equilibrium. They’re just kids caught up in circumstances over which they have little control, trying to make sense of their own confusion and the emotional chaos of the adults around them. Generally speaking, the higher a child’s Adverse Childhood Experiences Score, the higher her allostatic load, and the more likely she will have a high degree of physical and neural inflammation, and that her body and brain may eventually pay a steep physical cost for that early emotional suffering.

Yet some people who’ve faced a lot of adversity fare better than others. Not every single person with an Adverse Childhood Experience ends up with heart disease, an autoimmune condition, or an anxiety disorder. The correlation is high, but it is not a given.

Most kids who have suffered from toxic stress and adverse experiences do not recover without help. And as adults they are all too often still swimming unaware against the hard and invisible current of those emotional forces from long ago, as they try to make their way toward a happy and fulfilling life. It doesn’t matter what type of Adverse Childhood Experience a child faces: all ten categories of ACEs can cause very similar biophysical changes and inflammation. Yet the effect of childhood stress on body, brain, and mind differs for each of us, but not always for the reasons we think it will.

When stressors are strong, frequent, and prolonged, such as chronic neglect, physical or emotional abuse, living with a caregiver who has an addiction or mental illness, or coming of age in a violent environment, and this happens without adequate adult support, stress becomes toxic.

Having supportive, responsive relationships with caring adults as early in life as possible makes a profound difference.

Brain development from birth to eighteen is shaped by experiences, but our genetic makeup also influences the way our body and mind perceive and respond to stress. Some people are genetically primed to be more sensitive to what’s going on around them in their environment, including any family trauma or hardship they encounter when very young. Others aren’t as deeply affected by early adversity; things don’t hit them quite so hard.

One of the reasons for this difference exists deep within our genetic code.

The Sensitivity Hypothesis explains how and why some people are predisposed to stress reactivity. Roughly 15 percent of the general population possesses a variant of a behavioral gene called 5HTTLPR, which regulates the neurotransmitter serotonin. Serotonin influences our ability to rebound from emotional trauma and distress.

This Sensitivity Gene exists in three variants. People with the short/short variant tend to be highly sensitive to whatever they meet up with in their day-to-day life. When something stressful happens, they may be less able to recover quickly, but they’re also more deeply affected by positive influences; when they receive the right kind of nurturance, they do better in life. A mentor who has faith in them or recognizes that they have a gift or skill will profoundly shape them for the better. They soak in the good.

5-HTTLPR, the seratonin transporter.

The short/long expression of the serotonin gene doesn’t seem to affect people either way very much. However, the long/long expression of this gene is associated with having a greater ability to bounce back from adversity and more easily regain one’s footing after stressful events. When bad things happen, those with the long/long variant don’t fret or feel it quite so much. What might overwhelm other people in life is the proverbial water off the duck’s back. So, they don’t end up carrying around such a heavy allostatic load as they go forward in life.

But what’s most intriguing about the Sensitivity Hypothesis gene is that it plays a far more profound role in the more vulnerable years of childhood, when the brain is still developing, than it does in how affected we are by stress once we become adults.

People with this Sensitivity Gene variant who experience adversity when growing up face the greatest likelihood of suffering from depression in adulthood.

The reason is this; the Sensitivity Gene influences the developing stress response in such a way that, when “sensitive kids” are faced with adversity, their HPA stress axis pumps out even more stress hormones. They get a double dose of inflammatory drip from early on, and for a very long time.

In one fascinating study researchers asked several groups of adolescents to perform tasks in a lab setting while receiving ambiguous or negative feedback from observers. One group of teens possessed the short form of the Sensitivity Gene, and had also experienced some type of childhood adversity before the age of six; a second group of teens had the Sensitivity Gene, but hadn’t experienced early adversity. Both groups performed tasks such as discriminating between two images on a computer screen that matched or didn’t match or playing memory games. They couldn’t tell if researchers thought they were doing a good job or not because researchers were intentionally giving them mixed feedback.

The adolescents who carried the Sensitivity Gene and had faced childhood adversity showed more anxiety and made more mistakes while performing the tasks. They assumed that the sometimes discouraging, nonverbal feedback they were getting from evaluators meant they’d done something wrong. These same kids also showed signs of cognitive and emotional difficulties that are associated with later anxiety and depression.

Kids with the Sensitivity Gene who didn’t experience childhood adversity didn’t show the same reactivity to ambiguous feedback or have trouble regulating emotions. Because they hadn’t experienced Adverse Childhood Experiences, the Sensitivity Gene hadn’t kicked in.

There are other gene variants that contribute to children’s biophysical vulnerability to early stress. Duke researchers found that kids from high-adversity backgrounds who also carried a common gene variant, NR3C1, which, like 5-HTTLPR, makes some children more sensitive to their environment, were much more likely to develop serious problems as adults. This NR3C1 gene, or what we might call the Stress Vulnerability Gene, influences the body’s output of cortisol during stress. Seventy-five percent of kids with the stress-reactive variant of this gene developed psychological challenges or addictive behaviors by age twenty-five.

However, when kids with this Stress Vulnerability Gene also received intervention through programs that offered them support, only 18 percent developed psychological disorders and addictions as adults. In other words, the children with the vulnerability gene variant were highly susceptible to stress, but they were also very remarkably responsive to adult help, it made all the difference in their lives.

If you have the Sensitivity Gene or the Stress Vulnerability Gene and faced your share of adverse experiences in childhood, you may find that you are emotionally wired with a hair-trigger stress response. The trajectory of your life may be fraught with more difficulty. For instance, you may be more likely to feel anxiety and fear when a car veers in front of you or someone criticizes your idea at the office or something goes bump in the night. You may have a low-simmering, interior sense that you are not safe. You may pick up on other people’s discomfort and anxieties and absorb their stress without even realizing how much it is affecting you and your biology.

Georgia, raised by her cold, controlling mother and a dad with a temper, recalls that she picked up on tension in her home “before arguments even happened,” but her sisters were “more oblivious, and a lot tougher.” They didn’t seem to have the emotional antennae Georgia did. As her sisters neared adolescence, they stood up to her mother and started to “give it right back,” Georgia says. “They weren’t afraid, sometimes they even went head to head with my mom; they were sassy and exerted their power.”

By then, Georgia had already been dubbed by her family as “too sensitive” or “the sensitive one.” Labeling her in this way allowed her parents to pretend the tensions in their family were normal, that Georgia was the problem.

“I took in every negative vibe in the family. Eventually, to protect myself, I learned to shut myself down, even if I couldn’t shut down my sensors,” Georgia says. “By the time I was ten, I’d learned to do what I was told; I made a daily, conscious effort to be as invisible as a human being could possibly be.”

When Georgia was thirteen, her mom went to a therapist. Her husband was drinking heavily, and sometimes driving while drunk. Georgia says, “My mother had had a very abusive mother herself, and she’d lost her father whom she’d adored. She was well educated and more or less stuck at home with three small girls. My father told her, ‘I’m not paying for therapy, no wife of mine is going to a shrink.’ ”

Her mom took on a part-time job at a local library to pay for her therapy. She didn’t change very much toward Georgia, but, looking back, Georgia appreciates how hard it must have been for her mother to take those steps.

Georgia threw herself into her schoolwork. “I repressed everything except for my intellect.” It paid off, her desire to succeed in her own right might even have saved her life. When she was eighteen, Georgia went off to Columbia, where she eventually got her PhD.

Today, at age forty-nine, Georgia wonders a lot “about the multigenerational piece,” she says. “My mother’s mother was abandoned when she was a baby; my grandmother was very damaged. She was abusive to my mother, who, in turn, was a deeply injured person. The same was true on my father’s side, he’d had no real parents who looked out for him. My father’s father was depressed and an alcoholic. So was my father.” Georgia pauses. “It’s as if all those generations of pain landed on my back.”

“I have a very sensitive system that picks up on what other people can’t always sense,” she says. “Being able to sense and see what was going on beyond the superficial helped to protect me in a way, I knew when to retreat. But I was also a pain sponge. l absorbed my father’s pain, my mother’s pain, the pain of their damaged marriage.”

As an adult, in addition to degenerative disc disease, depression, and fibromyalgia, Georgia has also faced trouble in her relationships. She married in her early twenties, hoping to rewrite her own family’s unhappy story by creating a more loving and supportive home of her own, a safe haven.

But the marriage didn’t last. Georgia found it difficult to communicate and voice her feelings and needs honestly, as did her husband. Over time, lack of communication broke down their relationship. After she divorced, Georgia came to have this “strong inner vision” that there had to be a very different way of loving and living than what my parents had demonstrated for me. If I couldn’t find that road, I didn’t know if life was really worth it. I knew I either had to get on a journey toward physical and emotional healing or fold it all up and pack it in.”

Despite everything Georgia knows about her childhood, she finds it “daunting” to answer yes to several ACE questions but relieved to know that she “wasn’t ‘too sensitive’ all those years,” after all.

Georgia’s descriptions of her childhood illustrate the Sensitivity Hypothesis and the Vulnerability Hypothesis at work: some children see more, perceive more, know more, feel more. These are the same children who may carry even deeper psychic wounds from their adversity-laden childhood, and who may grow up to face more pressing physical and emotional symptoms in the future. This doesn’t mean that what happened was less traumatic than they think it was; it means that they felt the pain of it more deeply.

Still, the Sensitivity Gene brings with it distinct neurobiological pluses. The same plasticity of the brain that makes sensitive children highly reactive to stress also makes them more intuitive and receptive, more easily shaped by what is good and healthy in their environment, too: the support they’re shown, the loving relationships they experience, the caring mentor who sees something special in them and takes them under his or her wing. Even later efforts in adulthood to reshape and rehabilitate their own brains may bring them greater healing results.

When “sensitive” children experience a supportive, nurturing childhood, they actually show the fewest signs of depression in later life, even compared to those with the long/long version of the gene. They become even more likely than other people to develop positive and beneficial psychological characteristics, and to thrive. Even after suffering as children, their adult behaviors are still malleable, which translates into a profound ability to change after they become adults, despite their history.

Regardless of what happened when you were young, regardless of your sensitivity, if you set out to rehabilitate your brain and downshift your stress reactivity, you have a very good chance of doing so.

Georgia is sensitive; her intuitive makeup made her childhood more painful; but that same inner, creative sensitivity is what gave Georgia her “strong inner vision” that life could be different. And that inner vision would later propel Georgia on a transformative healing journey as an adult.

The Sensitivity Gene can make you more adept at learning how to deal with life’s inevitable suffering, and help you to learn to turn the fallout of childhood adversity into grist for remarkable self-growth.


Childhood Disrupted. How Your Biography Becomes Your Biology, and How You Can Heal

by Donna Jackson Nakazawa

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