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The Stress Response System

The human brain reflexively responds to intensely stressful situations by initiating a protective hormonal cascade that regulates many of the body’s major organs. The acute stress response, also known as the “fight-or-flight” response, prepares the body to fight a threat or to flee to safety. Hormones, such as cortisol and adrenaline, stimulate essential functions and suppress nonessential functions. Some effects of triggering the stress response system include: increased heart rate (heart), blood pressure (blood vessels), increased respiratory rate (lungs), increased glucose (liver), decreased digestion (stomach), tunnel vision (eyes), and sweating (skin).

Acute Stress Response / Fight or Flight / Childhood Stress / Childhood Trauma / Adverse Childhood Experience / ACE / Toxic Stress / KidsMates / Dr. Rosemary Martoma

 The Acute Stress Response. A KidsMates Graphic.

The same stress hormones that are protective during the acute stress response can cause damage during chronic (excessive or prolonged) activation, such as during an adverse childhood experience (ACE). In 2004, Radley, et al. demonstrated that chronic stress resulted in significant decreases in the total length and number of branches in the neurons (brain cells) of rats. Chronic stress caused shrinkage in areas of the brain responsible for mood and impulse control and caused expansion in areas of the brain responsible for fear and anxiety. 

Chronic Stress Alters Brain Architecture
Chronic Stress / Prolonged Stress / Excessice Stress / Adverse Childhood Experience / ACE / Toxic Stress / KidsMates / Dr. Rosemary Martoma

 Chronic Stress Alters Brain Architecture (Rat Neurons). (Top) Decreased neuronal length and branching in rats exposed to chronic stress (right). (Bottom) Chronic stress results in fewer dendritic spines (or “neuron connectors”), which impairs communication between brain cells. [Text and arrows added for clarity]

In 2005, the National Scientific Council on the Developing Child coined the term “toxic stress” to describe how chronic stress leads to long-term wear and tear on the brain and body. They analogized the damage to the effects of revving a car for days or weeks at a time.

They also divided the spectrum of childhood stress responses into three distinct categories:

  • Positive Stress: A mild, acute stressor triggers a brief stress response. Physiological changes spontaneously return to baseline after the threat is resolved. Positive stress results in healthy childhood development. Examples of positive stress include getting a shot or stubbing your toe.

  • Tolerable Stress: A severe stressor triggers a vigorous stress response. Supportive relationships with adults can restore the physiological changes back to baseline. In the absence of these protective relationships, tolerable stress can become toxic stress. This unbuffered stress can lead to developmental damage. Examples of tolerable stress include the death of a loved one or a frightening injury.

  • Toxic Stress: Severe, chronic, and unbuffered stress causes excessive or prolonged activation of the stress response system. Toxic stress causes damage to a child’s developing brain and immune, metabolic, and cardiovascular systems. Examples of toxic stress include adverse childhood experiences such as childhood abuse, household dysfunction, or childhood neglect.

3 Types of Stress Response
Positive Stress / Tolerable Stress / Toxic Stress / Stress Response / KidsMates / Dr. Rosemary Martoma

Three Types of Stress Response. A KidsMates Graphic.

Childhood stress in moderation is a normal part of healthy development. Childhood stressors can range from mild (such as a disrupted routine) to severe (such as physical abuse). Similarly, different children can respond to the same stressor with a wide range of responses. While one child may be excited about the first day of school, another child may be fearful and anxious.

When stress is excessive or prolonged, it can become harmful. Many children aren’t able to recognize or communicate stress overload. In these situations, it is common for children to express their stress through behavioral or physical signs. 

Some signs of childhood stress include:

  • Behavioral changes: Sadness, Frequent Tearfulness, Irritability, Anger, Aggression, Defiance, Withdrawal, Clinginess, new or recurring Fears (of being alone, being in the dark, being with strangers, or becoming sick), School Refusal, or Difficulty Concentrating.

  • Regressive Behaviors: Temper Tantrums, Thumb-Sucking, Baby-Talk (in older children).

  • Nervous Habits: Nail-Biting, Hair Twirling, Lip Licking.

  • Physical Complaints: Headaches and Abdominal Pain are common. 

  • Appetite Changes: Undereating, Bingeing.

  • Bowel Motion Changes: Constipation and Diarrhea.

  • Sleep Disturbance: Nightmares, Insomnia, and Bedwetting (new-onset).

  • Self-harm: Cutting, Burning, Eating Disorders, Risky Sexual Behavior, and Drug and Alcohol Use.

Signs of stress are analogous to levels on a volume controller. At low volumes, these signs, like the daily “buzz” of life, are background noise indicating that a child is experiencing stress. This stress often can be managed with supportive care. At higher volumes, signs of stress interfere with a child’s daily functioning, and caregivers should consider consulting a health care professional to discuss optimal management. Signs of self-harm are always dangerous and require immediate medical attention.

Signs of Childhood Stress Overload
Stress Overload
Toxic Stress
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