Physical and psychological distress play a role in the development of autoimmune disease as Hashimoto’s thyroiditis. Many studies confirm the effect of different stressors on the function of the immune system. In addition, many retrospective studies have shown that up to 80% of patients reported uncommon emotional stress before disease onset.
The immune system plays a role in sensing threats. But what happens when it has been programmed to stay in constant alert? And what are the factors that influence this programming?
A biological embedding model postulates that childhood stress gets ‘programmed’ into macrophages through epigenetic markings, posttranslational modifications, and tissue remodelling. As a result of distress, cells are prone to excessive inflammatory signalling via exaggerated cytokine responses to challenges and decreased sensitivity to inhibitory hormonal signals. In addition to the other exposures and genetic predispositions, the inflammation causes pathogenic mechanisms which lead to chronic disease.
There is evidence that brain-to-immune interactions are highly modulated by psychological factors which influence immunity and autoimmune disease. Early adverse circumstances are shaping the developmental trajectories, particularly in the areas of stress reactivity and physical or mental health.
Early childhood is an extremely delicate period in human development. During this period the brain, specifically the circuitry governing emotion, attention, self-control and stress, is formed by the interplay of the child’s genes and experiences. Childhood ill-treatment modiﬁes the relationship of depression with hippocampal volume. Childhood ill-treatment (emotional neglect, psychological, physical, sexual abuse) decreases hippocampal volume which is related to major depressive disorder.
The childhood adversities, even subtle forms of childhood stress (e.g. having a depressive parent) leads to changes in the brain in size and volume, altering the expression of the genes that control a stress hormone output, triggering an overactive inflammatory stress response and predisposing to adult disease. Early life stress can induce multiple changes across the brain-gut axis that contribute to the susceptibility to develop stress-related disorders.
How the gut functions: digestion of food, presence of food sensitivities and/or allergies, and processing of stress may be a sign of earlier difficult life experiences. Recent study reports that people with altered microbiomes have differently shaped brains. The hypothesis is that it is probable that this relationship isn’t unidirectional. The scientists state that the signals the gut and its microbes get from the brain of someone with an early adverse event history may lead to lifelong changes in the gut microbiome.
The environment in which a person grows up has a considerable impact on the development of hormonal responses to stress. Any imbalance to an organism’s homeostasis produces a complex stress response that involves the coordinated activation of neuroendocrine and autonomic systems. The hypothalamic–pituitary–adrenal (HPA) axis is important. It is triggered by stressors of various sources (physical, emotional, immunological, etc.) to provoke the systemic release of glucocorticoids. And as we know, the hypothalamus is the centre of the brain which controls production of thyroid hormones. It senses low circulating levels of thyroid hormone T3 and T4 and releases thyrotropin-releasing hormone (TRH). Further, TRH stimulates the anterior pituitary to produce thyroid-stimulating hormone (TSH).
HPA axis’s development and maturation, also called the stress axis, is influenced by the safe environment people encounter as kids. Adverse early experience has an continuous impact on the responses to stress, which is marked by an abnormal metabolism of thyroid hormones, which reprograms how the axis responds to stress later in life. Early life trauma is associated with decreased peripheral levels of thyroid-hormone T3 in adolescents. The quality of maternal care is associated with changes in the relationship between the precursor thyroid-hormone T4 and the more active T3. Good maternal care is associated with increased conversion of T4 to T3.
It is presumed that the stress-triggered neuroendocrine hormones lead to immune dysregulation, which ultimately results in autoimmune disease, by altering or amplifying cytokine production.
The autonomic nervous system is shaped by experience. As a result of our experiences we develop a personal neural manner in the way we habitually respond. The autonomic nervous system is regulated by the vagus nerve. The vagus nerve, the wondering nerve, travels from the brain stem to the heart and stomach and upward to the face via the connection with other cranial nerves. The vagus nerve is the longest nerve of the organism and a major component of the parasympathetic nervous system which constitutes the autonomic nervous system (ANS), with the sympathetic nervous system. Vagus nerve is composed of sensory and motor fibers that innervate most organs in the body e.g. gastrointestinal and cardiovascular systems as well as the ears, mouth and voice.The vagus nerve is a major constituent of the inflammatory reflex which controls innate immune responses and inflammation.
The vagal brake allows us to rapidly regulate ourselves by bringing us to calm state. This ability for rapid regulation and smooth transitions is influenced by traumatic experiences. We are wired to search safety in the presence of another. Our physiology is regulated in connection to one another. When we have missed opportunities to co-regulate in childhood, we carry the distress in our nervous system and the vagus brake is not working properly.
What if there is a way to help?
Stress is inevitable part of life and not bad per se. When under stress, healthy individuals quickly respond, come back to the baseline and recover. Stress can influence the immune system, either by stopping it responding to stress or by bringing an overstimulation and an exaggerated reaction, as it generally occurs with autoimmune diseases as Hashimoto’s, where the stress response is not shut off.
While early events shape nervous system, building new experiences can change it. What happened in the past does not need to keep repeating itself in the present. You can embed another definition of stress in your body and re-program your response. A good start is Hashimoto’s heart program: the only worldwide evidence-based program. If you need a more personal help, make an appointment