What is the impact of stress on development? The answer to that question is complex and depends on several factors, including the number of stressors, the duration of stress, and the individual’s ability to cope with stress.

Children experience different types of stressors that could be manifest in various ways. Everyday stress can provide an opportunity for individuals to build coping skills and poses little risk to development. Even long-lasting stressful events, such as changing schools or losing a loved one, can be managed reasonably well.

Some experts have theorized that there is a point where prolonged or excessive stress becomes harmful and can lead to serious health effects. When stress builds up in childhood, neurobiological factors are affected; in turn, levels of the stress hormone cortisol exceed normal ranges. Due in part to the biological consequences of excessive cortisol, children can develop physical, emotional, and social symptoms. Physical conditions include cardiovascular problems, skin conditions, susceptibility to viruses, headaches, or stomach aches in young children. Emotionally, children may become anxious or depressed, violent, or feel overwhelmed. Socially, they may become withdrawn and act out towards others, or develop new behavioral ticks such as biting nails or picking at skin.

Researchers have proposed three distinct types of responses to stress in young children: positive, tolerable, and toxic. Positive stress (also called eustress) is necessary and promotes resilience, or the ability to function competently under threat. Such stress arises from brief, mild to moderate stressful experiences, buffered by the presence of a caring adult who can help the child cope with the stressor. This type of stress causes minor, temporary physiological and hormonal changes in the young child, such as an increase in heart rate and a change in hormone cortisol levels. The first day of school, a family wedding, or making new friends are all examples of positive stressors. Tolerable stress comes from adverse experiences that are more intense but short-lived and can usually be overcome. Some examples of tolerable stressors are family disruptions, accidents, or the death of a loved one. The body’s stress response is more intensely activated due to severe stressors; however, the response is still adaptive and temporary.

Toxic stress is a term coined by pediatrician Jack P. Shonkoff of the Center on the Developing Child at Harvard University to refer to chronic, excessive stress that exceeds a child’s ability to cope, especially in the absence of supportive caregiving from adults. Extreme, long-lasting stress in the absence of supportive relationships to buffer the effects of a heightened stress response can produce damage and weakening of bodily and brain systems, which can lead to diminished physical and mental health throughout a person’s lifetime. Exposure to such toxic stress can result in the stress response system becoming more highly sensitized to stressful events, producing increased wear and tear on physical systems through over-activation of the body’s stress response. This wear and tear increases the later risk of various physical and mental illnesses.

Video 1. Toxic Stress DerailsHealthy Development explains some of the biological changes that accompany toxic stress.

The toxic stress that children endure can have a significant impact on their later lives. According to Merrick, Ford, Ports, and Guinn (2018), the foundation for lifelong health and well-being is created in childhood, as positive experiences strengthen biological systems while adverse experiences can increase mortality and morbidity Adverse Childhood Experiences, or ACEs, are potentially traumatic events that occur in childhood (0-17 years) such as experiencing violence, abuse, or neglect; witnessing violence in the home; and having a family member attempt or die by suicide. Also included are aspects of the child’s environment that can undermine their sense of safety, stability, and bonding such as growing up in a household with substance misuse, mental health problems, or instability due to parental separation or incarceration of a parent, sibling, or another member of the household. Traumatic events in childhood can be emotionally painful or distressing and can have effects that persist for years.2 Factors such as the nature, frequency, and seriousness of the traumatic event, prior history of trauma, and available family and community supports can shape a child’s response to trauma.

Some groups have been found to be at a greater risk for experiencing ACEs. Merrick et al. (2018) reviewed the results from the 2011-2014 Behavioral Risk Factor Surveillance System, which included an ACE module consisting of questions adapted from the Centers for Disease Control and Prevention. Each question was collapsed into one of the eight ACE categories: physical abuse, emotional abuse, sexual abuse, household mental illness, household substance use, household domestic violence, incarcerated household member, and parental separation or divorce. The results indicated that 25% of the sample had been exposed to three or more ACEs, and although ACEs were found across all demographic groups, those who identified as Black, multiracial, lesbian/gay/bisexual, having less than a high school education, being low income, and unemployed experienced significantly higher ACE exposure. Assisting families and providing children with supportive and responsive adults can help prevent the negative effects of ACEs.

Consequences of ACEs and Toxic Stress

An estimated 62% of adults surveyed across 23 states reported that they had experienced one ACE during childhood and nearly one-quarter reported that they had experienced three or more ACEs. ACEs can have negative, lasting effects on health, wellbeing, and opportunity. These exposures can disrupt healthy brain development, affect social development, compromise immune systems, and can lead to substance misuse and other unhealthy coping behaviors. The evidence confirms that these exposures increase the risks of injury, sexually transmitted infections, including HIV, mental health problems, maternal and child health problems, teen pregnancy, involvement in sex trafficking, a wide range of chronic diseases and the leading causes of death such as cancer, diabetes, heart disease, and suicide. ACEs can also negatively impact education, employment, and earnings potential. The total economic and social costs to families, communities, and society is in the hundreds of billions of dollars each year.

Figure 1. Risk of outcomes due to adverse childhood experiences.

Children who experience toxic stress or who live in extremely stressful situations of abuse over long periods can suffer long-lasting effects. The structures in the midbrain or limbic systems, such as the hippocampus and amygdala, can be vulnerable to prolonged stress (Middlebrooks and Audage, 2008). High levels of the stress hormone cortisol can reduce the size of the hippocampus and affect a child’s memory abilities. Stress hormones can also reduce immunity to disease. If the brain is exposed to long periods of severe stress, it can develop a low threshold, making a child hypersensitive to stress in the future.

With chronic toxic stress, children undergo long-term hyper-arousal of brain stem activity. This activity includes an increase in heart rate, blood pressure, and arousal states. These children may experience a change in brain chemistry, which leads to hyperactivity and anxiety. Therefore, it is evident that chronic stress in a young child’s life can create significant physical, emotional, psychological, social, and behavioral changes; however, the effects of stress can be minimized if the child has the support of caring adults.

Video 2. How Childhood Trauma Affects Health Across a Lifetime discusses the development of an ACE assessment and the research results on outcomes.

Preventing ACEs

The Centers for Disease Control and Prevention (2019) suggests several strategies that can prevent ACEs from happening in the first place as well as strategies to mitigate the harms of ACEs. The evidence tells us that ACEs can be prevented by strengthening economic supports for families, promoting social norms that protect against violence and adversity, ensuring a strong start for children and paving the way for them to reach their full potential, teaching skills to help parents and youth handle stress, manage emotions, and tackle everyday challenges. connecting youth to caring adults and activities, and intervening to lessen immediate and long-term harm.

Figure 2. Strategies for preventing adverse childhood experiences.

Video 3. Preventing ACEs discusses how communities can reduce the risk for adverse childhood experiences.

Stress is encountered in four different stages. In the first stage, stress usually causes alarm. Next, in the second or appraisal stage, the person attempts to find meaning from the event. Stage three consists of the individual seeking out coping strategies. Lastly, in stage four, people execute one or more of the coping strategies. However, individuals with a lower tolerance for stressors are more susceptible to alarm and find a broader array of events to be stressful. These children often experience chronic or toxic stress.

Video 4. The Science of Resilience describes a variety of factors involved in the development of resilience.

Some recommendations to help children manage stressful situations include:

• Preparing children for everyday stressful situations, such as traveling to new places or going to the doctor. For example, talk to children about the experience to help them understand that it is okay to be stressed and scared.
• Keeping communication open. This includes making sure that the child feels comfortable talking to a person. This may include being in a comfortable space, such as their bedroom, where they feel safe. The comfort level of the child is important because if a child is not comfortable, or feels forced to speak, they may not open up at all.
• Spending time together as a family so that no one’s feelings go unseen, ensuring that a child knows that their feelings are valued, and should be expressed in healthy ways.
• Modeling healthy and successful coping mechanisms (such as going for a walk).
• Encouraging children to express themselves creatively (as an outlet or to help others to understand what is stressing the child). Some healthy outlets of stress relief include sports or running, writing, reading, art, as well as playing musical instruments.
• Teaching children to act and think positively when they are faced with a situation to manage the stress before it becomes overwhelming.
• Providing a safe and healthy home and environment for children.
• Providing children with proper nutrition and attention.
• Ensuring children are not exposed to substance abuse or violence. When a healthy environment is provided, children are more likely to be emotionally and physically healthy