The Root of the Root - Part 1
How early life stress reshapes the nervous system, immune response, and gut — long before symptoms appear.
For most of my life, I didn't have a diagnosis. I had symptoms — stubborn weight, brain fog, chronic fatigue, mood swings that felt outsized for my circumstances, and a body that seemed to be working against me no matter how hard I tried. I didn't have a diagnosis, but I did have a story. And it turns out, that story was written in my biology long before I ever understood the language.
It started at thirteen.
The Root of My Gut Issues Wasn’t Food — It Was Trauma
What I experienced between the ages of thirteen and sixteen is something I now understand to have a name: complex developmental trauma. Not a single catastrophic event, but a prolonged period of anticipatory grief, fear, and helplessness — the particular kind of dread that lives in your body when your mom is sick and you don't know how to hold that, because your nervous system is still being built.
The death that eventually came wasn't clean. My mom recovered, and then she had a cancerous return, which she hid, and then a surgery that should have been survivable. And then she was gone. No gradual preparation. No real goodbye. Just absence where there had been presence.
My Nervous System Reorganized
That kind of loss at sixteen doesn't just break your heart. It fundamentally reorganizes your nervous system's threat detection system. And here is what most people don't understand: your nervous system and your immune system are not separate. They are in constant conversation. When one is dysregulated, the other follows. A developing adolescent body that is held in a prolonged state of fear and grief is a body whose immune architecture is being shaped by that stress — at precisely the moment it is most vulnerable to being shaped.
And at the center of that immune architecture is the gut.
The gut is not simply a digestive organ.
It houses approximately 70% of the body's immune cells, produces more than 90% of the body's serotonin, and communicates with the brain through what researchers now call the gut-brain axis — a bidirectional highway of chemical signals, nerve pathways, and immune messengers that runs in both directions, constantly. When the nervous system is under chronic stress, that signal travels directly to the gut. It alters motility, increases intestinal permeability, shifts the microbial balance, and suppresses the local immune defenses that keep opportunistic organisms like Candida in check.
So when I trace the origin of my gut dysfunction, I cannot start with the antibiotics, the Acutane, the incredible loads of stress I grew into, or alchohol consumption — though they matter enormously, and you will read about them in detail. I have to start earlier.
I have to start with a thirteen-year-old girl sitting with anticipatory grief in a body that didn't yet know how to hold it, whose stress response was quietly reshaping the terrain that the all the things mentioned above would later devastate.
The cascade didn't begin in my gut. It began in my nervous system. And the gut was simply the place where it became impossible to ignore - in my 40’s.
Thanks for reading part 1. Below is the science in which this discussion is based. Part 2 will reveal how, when and why my gut became so dysfunctional. Part 3 will deep dive into the science.
I am so glad you are here. If this resonates, I’d love to hear from you. If you’d like to have parts 2 and 3 sent direct to your inbox, please sign up for The Notes below. Each article will land right in your inbox.
Nervous System & Trauma — Supporting References
The brain and immune system are not fully formed at birth — they continue to mature in response to the environment, and psychosocial stressors during childhood can affect immune system development, which in turn affects brain development and long-term functioning: Neuropsychopharmacology — Psychoneuroimmunology of Early-Life Stress: The Hidden Wounds of Childhood Trauma, King's College London / PMC (2016)
Early adversity during sensitive developmental periods results in structural changes to the amygdala, hippocampus, and prefrontal cortex — the regions that respond to threat and regulate the HPA axis — producing a phenotype that is chronically threat-sensitive: ScienceDirect — Childhood Trauma and Hair Cortisol Response (2024)
Hyperarousal of the sympathetic nervous system with sustained allostatic load along the HPA axis is the theorized basis for adult psychopathology following childhood trauma; adverse environmental stimuli become biologically incorporated into the structure and function of the adult brain: Frontiers in Psychiatry — Childhood Trauma, the HPA Axis and Psychiatric Illnesses (2022)
The biological effects of childhood trauma on stress systems — including the immune system, the HPA axis, the serotonin system, and epigenetic factors — and how developmental trauma shapes the body's lifelong ability to regulate its stress response: PMC — The Biological Effects of Childhood Trauma (2014)
Early life stress produces lasting alterations in emotional and autonomic reactivity, immune dysregulation, and gut microbiome disruption — with effects detectable even decades later: Frontiers in Psychiatry — Developmental Trajectories of Early Life Stress: A Narrative Review (2019)
Parental bereavement in children is directly linked to HPA axis dysregulation and elevated cortisol stress responses — including associations with anxiety, depression, posttraumatic stress, and maladaptive grief: PMC — Psychological and Environmental Correlates of HPA Axis Functioning in Parentally Bereaved Children (2018)
Childhood adversity is associated with immune dysregulation across multiple indices — including inflammatory cytokine production, increased illness susceptibility, and epigenetic alterations — with greater emotional reactivity to daily stress in those with early trauma history: Frontiers in Psychology — Immune and Epigenetic Pathways Linking Childhood Adversity and Health Across the Lifespan (2021)
