Donna Jackson Nakazawa is the author of seven books about what she likes to call “gnarly problems” that span the intersection of science, emotion, and human life, most recently the book Girls on the Brink. One of the gnarly topics she’s done a deep dive on is something called psycho neuroimunology, which is the field that looks at the interplay between our mind and our immune system. As she learned in her research, the relationship between the two is strong — and it all starts in childhood. Read on to learn more about the emerging field of psycho neuroimmunology, what it has to do with adverse childhood experiences (ACE) research, how emotions affect the body physically by way of the brain, and more.
What Exactly Is Psycho Neuroimmunology?
Nakazawa’s interest lies in exploring what’s happening in scientist’s labs and using that research to help people live healthier, happier lives in the real world. This means she’s tackled lots of different topics, but one of the most exciting fields is one that’s only just emerging: psycho neuroimmunology.
She explains that over the past 10 to 15 years, the field of psycho neuroimmunology has expanded exponentially, with more and more research showing the complex and interconnected nature of three factors: our thoughts, our stress response, and our immune system. “The last decade has just been mind-blowing in terms of our understanding of how the body and the brain are talking to each other, what they’re chatting about, and how that affects our health,” Nakazawa says.
While this might seem sort of in the weeds of research labs, Nakazawa says that psycho neuroimmunology actually has huge implications for the general population. “If you can explain neuroimmunology to people in the right way with the right stories, the right images, and with the right depth, it changes their ability to do the work, to be better able to respond to the nonstop stressors that are coming at us in today’s world,” she says.
To understand what she means by that and how that plays out, we need to take a few steps back and start at the beginning.
Getting Sick and Looking for Answers
When Nakazawa was writing her book The Autoimmune Epidemic, she began to get very sick. She already knew that she had thyroiditis, an autoimmune disease, as well as small fiber sensory neuropathy, which is a neurological immune disease, but she soon added another diagnosis to the list: Guillain-Barré syndrome (GBS). GBS is a very rare autoimmune disease that has similarities to multiple sclerosis, with symptoms including weakness, fatigue, and numbness or tingling of body parts. She recovered, then relapsed, and spent weeks at a time at the hospital whenever the symptoms would flare up.
She was also raising two young children, and knew that living this kind of life, at the mercy of her autoimmune disease, was just not acceptable. “It really left me at a disadvantage raising my beautiful son and daughter,” she remembers. “I spent six months in a wheelchair the second time I had Guillain-Barre, and it changed their lives dramatically. I couldn’t walk up the stairs, I had extreme exhaustion. I just wanted to be healthy for my kids. During that time, as I was actually writing the book about autoimmune disease, I thought, ‘Okay, I really have to double down here.’”
In her research and writing, she’d also developed a growing understanding of the fact that autoimmune diseases primarily affected women, and that these women were not being taken seriously by their physicians. “The gaslighting that was going on around autoimmune disease a little more than a decade ago would totally floor someone listening today,” she says. “So we know medical gaslighting is still all the rage. But at that time, the average woman that I was interviewing with autoimmune disease had been written off by so many doctors that her fight to find answers and validation and healing in the medical community was enraging to witness.”
For her part, Nakazawa was lucky to have a good neurologist who listened to her and helped her get the treatment she needed (but she still had to deal with esteemed researchers and doctors in the field asking questions and making statements that cast doubt on the reality of her diagnosis and symptoms).
Once she’d fully recovered and finished her book, she set out to learn everything she could about autoimmune disease and the different ways it affected men and women — and exploring that meant diving headfirst into the field of psycho neuroimmunology. “I went on this year-long journey to try to figure out everything I could about psycho neuroimmunology to bring down my own stress response and shift my brain, so that I could be the parent and the human and live the life that I felt was there if I could figure out a way to do it,” she says.
Finding Answers in ACE Research
During her year-long quest, Nakazawa came across a landmark study from 1998 that changed how she thought about everything: The Adverse Childhood Experiences (ACE) Study. “It had already been out for a while, but nobody was reporting on it, and I just couldn’t wrap my head around how such a major trend was not known to the average person,” she says. She explains that since that study came out, there have been more than 2,000 studies based on it reaffirming what the original study found: adverse experiences during childhood have an impact on your mental and physical health in adult life.
As she explains, the ACE research shows that there is a “dose-dependent relationship” between the number of categories of adversity someone experiences before they turn 18 and their chance of physical or psychological disease later in life. What that means in layman’s terms is that the more types of negative experiences people have as a child, the greater their odds of developing autoimmune and other diseases. Reflecting on her own childhood and autoimmune diagnoses, Nakazawa can pinpoint the ACE that affected her life: her father died from a medical accident when she was very young, changing her family life dramatically. (To see if you have any Adverse Childhood Experiences that may be impacting your health, you can take the ACE test.)
And while ACE’s negatively impact people of all genders, of particular interest to Nakazwa was the disproportionate impact that ACE’s seemed to have on females. “For women in particular, we generally find that for every category of ACEs you experience growing up, your chance of later being hospitalized with an autoimmune disease rises by 20%,” she explains. “When I saw this research, again, I was like, ‘Okay, why aren’t we talking about this and why aren’t we doing something about it?’” she remembers.
Nakazawa explains that the reason for this link between ACE and autoimmune disease later in life is the fact that a person’s stress response — aka their fight-or-flight response — is determined during their childhood. For people with a heightened stress response, they spend more time with their sympathetic (fight-or-flight) nervous system turned on rather than their parasympathetic (rest and digest) nervous system, which sends their immune system into overdrive. “The stress response should turn on and off, like a faucet. It’s on when it’s appropriate, and turns off when you no longer need it,” she says. “But in people with ACEs, particularly three or more, the stress response in childhood gets turned on like a garden hose. Epigenetic shifts happen so that your stress response stays geared on high, because as a child, that’s what you needed. You needed to keep in that state of constant vigilance. Over time, it shifts the genes that oversee your stress response, setting it on high across the lifespan. And so it makes sense that we see more disease, more mental health issues, in relationship to ACEs.”
How Emotions Affect the Body via the Brain
So how, exactly, do negative experiences during childhood alter a person’s stress response? The answer lies in the interplay between the immune system and the brain (again returning to that word, neuroimmunology, where “neuro” refers to our brain and “immunology” refers to our immune system).
In 2011, researchers at Harvard discovered that the brain has its own fully functioning immune system, Nakazawa explains. The researchers were looking into the function of brain cells called microglia, which had been overlooked for a hundred years, but which they soon discovered were actually much more powerful than previously thought. The researchers found that while a baby is in utero, its microglia, which are white blood cells, break off from the other white blood cells and rise to the brain. From there, they become the brain’s resident immune cells that oversee how healthy a person’s synaptic neural connections (aka the connections between their neurons, the nerve cells responsible for sending messages throughout your body and allowing you to talk, walk, eat, etc) will be for life.
Just like the immune system in your body, your brain’s immune system is in constant conversation with the environment, scanning for threats and responding to them. Both immune systems have one job: to ensure that you’re safe. And while the body’s immune system responds to physical threats, the brain’s immune system is also responding to social and emotional threats.
To understand why this is the case, you need to look at it from an evolutionary perspective, Nakazawa says. “The reason your immune system starts to rev up in the face of social threats is because across evolutionary time, if you were not in social harmony, as part of your tribe, you would be set to the outside of the tribe,” she explains. “You would be the last person to get the meat or fresh fruit. You would be the first person to get picked off by marauding tribes or predators. If you’re fully ostracized, guess what? It’s over.”
Because of this, our brain’s immune system is conditioned to scan for social threats. It looks for any small sign of social harm — an insult, an eye roll — and these social or emotional threats cause a person’s immune system to rev up just as if it were a physical harm. “To our bodies, social and emotional threats actually have a higher, more long-lasting expense to our immune systems than do physical threats,” says Nakazawa. “I know it’s hard to wrap your head around.”
When a social or emotional threat is detected, the microglia in the brain transform from what Nakazawa describes as “lovely, little angel dancers” that help support the connections between neurons into “big, hairy, Pacman-like cells.” From there, they make the same mistakes as an overactive immune system in the body, acting as if they are under constant threat. “They over-respond and they start eating up neural synapses and later, we can see this on brain scans,” she says. “It looks like depression, anxiety, cognitive decline, Alzheimer’s disease.”
What’s more, the mind and the body are not separate, so the immune cells in your brain are talking all the time to the immune cells in the rest of your body. For people whose microglia have been conditioned to be constantly stressed in the brain, this can cause an overactive immune system in the rest of the body, which leads to — you guessed it — autoimmune disease.
How You Can Rewire Your Stress Response
For parents, seeing the impact of ACEs on a child’s lifelong health can be quite sobering. How can you ensure that you protect your child from ACEs and set them up for a healthy brain and immune system? The number one factor, Nakazawa says, is a strong parent-child connection and strong parent-child attunement. In fact, she explains, kids are 12 times more likely to thrive if they grew up with parents who could answer yes to one question: can your child talk to you about anything?
If a child feels safe telling their parent anything, they have a good chance of developing a healthy stress response. So what impacts that? “We’ve got to look at ourselves,” Nakazawa says. “We’ve got to look at how we manage our own stress, how we manage our own trauma, so that in those moments that are high stakes, high-octane parenting moments, we’re able to regulate ourselves.
The good news is that, even for those who experienced many ACEs, the stress response you developed in childhood is not a life sentence. There are things they can do to, as Nakazawa puts it, “bring down their stress machinery.” And while bringing down your stress response is certainly essential for parents, it’s also incredibly important for anyone with ACEs who is experiencing the negative effects of a heightened stress response, whether that be anxiety and depression, autoimmune disease, or something else.
Nakazawa runs several courses on rewiring your nervous system and shifting your stress response, many of which center around narrative writing exercises. Narrative writing, she explains, has been shown to reduce stress and anxiety for parents and help reduce chronic stress levels. “Especially during the pandemic, the research on narrative writing really grew, and we understand that it brings down our neurobiological, easily measurable, biomarkers for stress and inflammation,” she says.
Narrative writing differs from straight-up journaling in that it uses specific, science-based prompts developed from the field of neuroscience. The prompts, Nakazawa explains, are designed to help you get past your own resistance to answer questions about yourself and begin to understand and change your stress response.
“If you love your child, you must develop the skills to manage your own stress, your own trauma, your own history, so that you can be regulated,” she says. “Because every single thing that’s happening in your body will be mirrored in your child’s body and brain. If they’re coming to you with hard things, they have to know that you are that safe, attuned, listening parent who can hear them without your own emotional reactivity getting in the way.”
Watch our full interview with Donna Jackson Nakazawa to learn which childhood experiences are most associated with disease later in life (you’ll probably be surprised!), the specific ways neuroimmunology manifests in adolescent girls (and how this might explain the rising rates of depression and anxiety and the increase in early puberty among this group), how traumatic events affect gut health, the connection between all of this and long Covid, and much more.
Do you see any ways that ACEs impact your physical or mental health today? If you feel comfortable sharing, we’d love to hear your story in the comments below.
- Felitti, V J et al. “Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults. The Adverse Childhood Experiences (ACE) Study.” American journal of preventive medicine vol. 14,4 (1998): 245-58. doi:10.1016/s0749-3797(98)00017-8
- Dube, Shanta R et al. “Cumulative childhood stress and autoimmune diseases in adults.” Psychosomatic medicine vol. 71,2 (2009): 243-50. doi:10.1097/PSY.0b013e3181907888
- Schafer, Dorothy P et al. “Microglia sculpt postnatal neural circuits in an activity and complement-dependent manner.” Neuron vol. 74,4 (2012): 691-705. doi:10.1016/j.neuron.2012.03.026
The information contained in this article comes from our interview with science writer Donna Jackson Nakazawa. Nakazawa is the author of seven books, including, most recently, Girls on the Brink, which was named one of the best health books of 2022 by The Washington Post and Mashable. Her writing has been published in numerous publications, including The Boston Globe, The Washington Post, Parenting, Health Affairs, and she has appeared on The Today Show, NPR, NBC News, and ABC News. Her reporting has earned her many accolades, including the AESKU lifetime achievement award and the National Health Information Award, and she has spoken at numerous universities, conferences, and medical centers, including the Harvard Division of Science Library Series, the Andrew Weil Center for Integrative Medicine, Rutgers University Behavioral Health, Johns Hopkins Medical Institutions, the International Congress on Autoimmunity, and the Peace & Justice Institute. She received her B.A. from Duke University and is a graduate of the Radcliffe Publishing Procedures Program. You can learn more about Donna Jackson Nakazawa here.