Neurobiological and Systemic Effects of Chronic Stress

Summary & key facts

This paper reviews how ongoing stress changes the brain and the rest of the body. It explains that the brain decides what is dangerous and then triggers body responses that can help in the short term. But if those responses happen too often or for too long, they can harm brain circuits for thinking, mood and anxiety, and then cause lasting problems. The good news is the brain can rewire itself, so prevention and treatments that combine medicine and behavior can help, and public policies that reduce stress can protect health.

Key facts:

• The brain detects threats and then starts body responses that help people adapt. This process is called allostasis, which means keeping balance by changing how the body works.
• If the brain’s stress responses are used too much or become disorganized, they create 'allostatic load' or overload. That means the very systems meant to protect you can start to cause harm.
• Stress changes brain structure and function. These changes include making new neurons, reshaping nerve cell branches, and changing connections between cells.
• Stress can unbalance brain circuits that control thinking, decision making, anxiety and mood. That can make a person feel more anxious or low, or have trouble concentrating.
• Short-term stress responses can be helpful. But if the stressful state continues after the danger is gone, the ongoing changes may become maladaptive and often need treatment that combines drugs and behavioral therapy.
• Men and women can show different brain responses to stress. Also, bad experiences early in life can interact with a person’s genes to create long-lasting effects through epigenetic changes, which are chemical tags that alter gene activity.
• Because the brain can change (plasticity), there is hope for treatments that use both brain and body effects. Still, prevention and public policies that lower stress are important to protect long-term health.

Abstract

The brain is the central organ of stress and adaptation to stress because it perceives and determines what is threatening, as well as the behavioral and physiological responses to the stressor, which promote adaptation ("allostasis") but also contribute to pathophysiology ("allostatic load/overload") when overused and dysregulated. The adult as well as developing brain possesses a remarkable ability to show structural and functional plasticity in response to stressful and other experiences, including neuronal replacement, dendritic remodeling and synapse turnover. Stress can cause an imbalance of neural circuitry subserving cognition, decision making, anxiety and mood that can increase or decrease expression of those behaviors and behavioral states. This imbalance, in turn, affects systemic physiology via neuroendocrine, autonomic, immune and metabolic mediators. In the short term, these changes may be adaptive; but, if the threat passes and the behavioral state persists along with the changes in neural circuitry, such maladaptation requires intervention with a combination of pharmacological and behavioral therapies. There are important sex differences in how the brain responds to stressors. Moreover, adverse early life experience, interacting with alleles of certain genes, produces lasting effects on brain and body via epigenetic mechanisms. While prevention is key, the plasticity of the brain gives hope for therapies that utilize brain-body interactions. Policies of government and the private sector are important to promote health and increase "healthspan."

Topics

Birth, Development, and Health Child and Adolescent Psychosocial and Emotional Development Stress Responses and Cortisol

Categories

Behavioral Neuroscience Life Sciences Neuroscience

Tags

Allostasis Allostatic load Anxiety Chronic stress Clinical psychology Cognition Maladaptation Mood Neuroplasticity Neuroscience Psychiatry Psychology Stressor

Conditions & symptoms

Anxiety Burnout Depression PTSD Sleep disorder Anxiety or worry Difficulty focusing Lack of energy or motivation Poor sleep Sadness or low mood