Decades of medical research has shown that childhood adversity changes people in ways that can endure in their bodies for years. We now know that there is a biological connection between adversity and health. As practitioners and therapists it is worth considering a whole-system approach using the Adverse Childhood Experience questionnaire (ACE )as an assessment tool.

Adversity can tip a child’s development trajectory and affect physiology.  It can trigger chronic inflammation and hormonal changes that can last a lifetime. It can alter how cells replicate and it can dramatically increase the risk for heart disease, stroke and cancer, diabetes – even Alzheimer’s. Our biology literally pulls us up short.

Research show that the life expectancy of people living with ACE scores of six or more is twenty years shorter than it is for people with no ACEs (Burke Harris 2019).

1998 saw a pivotal article in the American Journal of Preventative Medicine: “Relationship of Childhood Abuse and Household Dysfunction to many of the Leading Causes of Death in Adults: the Adverse Childhood Experiences (ACE) Study”, by Dr. Vincent Felitti and Dr. Robert Anda et al.

The Human Stress Response

The human stress response can work too well when the response to stimuli goes from adaptive and lifesaving to maladaptive which damages our health.  PTSD is an example of the body remembering too much, the stress response repeatedly confuses present stimuli with the past so our bodies feel the same and in danger.  PTSD is entrenched, held in the past and stuck on repeat.

Coming Face to Face with the Bear

Imagine if you were out walking and were suddenly faced with a wild bear. You would probably be scared, your amgydala (fear centre) would temporarily turn down the rational, thinking part of your brain. The SAM axis (Sympatho-adrenomedullary) that initiates the production of adrenaline and noradrenaline (short acting stress hormones) would prime your body by making what you need to protect yourself or run from the bear.  At the same time your HPA axis (Hypothalmic – pituitary-adrenal) would trigger longer-term stress hormones, most notably cortisol which would raise your blood pressure and blood sugar and totally inhibit clear thinking.

Once safe from the bear, your SAM and HPA axes that are designed to shut themselves down would feedback high levels of adrenaline and cortisol back to the parts of the brain that initiated the stress response in the first place.

Living with the Bear

But sometimes our body’s stress thermostat is broken and this doesn’t happen. For children living with PTSD and complex PTSD their stress responses can be activated dozens and sometimes hundreds of times a day. Bruce and Fisher et al (2009) showed that cortisol has a predictable daily pattern: high in the morning and gradually decreasing reaching its lowest point in the evening before sleep.  Bruce and Fisher found that children who had experienced maltreatment had higher overall cortisol levels as well as a disruption of the normal daily patterning leading to high levels in the evening. They also found that children who had been exposed to some level of adversity did not tip over into dysregulation due to the right support from a loving care giver.

Different types of stress

Positive stress – normal and essential part of development

Tolerable stress – time-limited activation with a buffer of adult relationships to help recovery

Toxic stress – strong, frequent, prolonged or long term adversity

Healthy Development

A healthy development of the stress-response system needs a child to experience both positive and tolerable stress to allow the SAM and HPA axis to be calibrated to react normally to stressors. For every ACE, the risk of tolerable stress tipping into toxic stress increases.  The system responds more frequently and intensely to multiple stressors causing a dysregulated pattern and a biological ripple effect. The important ingredient for toxic stress is a caregiver’s ability to hold psychological space and act as a buffer.

Waving Goodbye to the Bear

Neuro-endocrine-immune system changes. Toxic stress can affect many of the body’s systems. Learning and behavioural problems, pleasure and reward centre of the brain, addiction, overactive amygdala (fear centre) which messes up our fear predictions, Locus Coeruleus aggression, anxiety and hyper-arousal, pre-frontal cortex executive functioning, social control, Hippocampus creation of long and short term memories, learning. Ventral Tegmental Area, rewards, motivation, addiction, risky behaviour,  Hormones – growth, sex hormone, thyroid hormone, obesity, metabolic disruption and insulin.  Immune system – inflammation, suppression, activation, deficiencies, hypersensitivity and immune disease.

The brain, the nervous and the immune systems not fully developed at time of birth and babies immune development occurs in response to its environment during the first few years of life. The production of high doses of adrenalin and cortisol limiting impulse control so anything that limits re-activation from the SAM and HPA axes are beneficial.


Dr. Nadine Burke Harris – The Deepest Well, Healing the Long Term Effects of Childhood Adversity

Gabor Mate – When the Body Says No