14.3 Stress and Illness

Stress, Emotions and Physical Health

Stress doesn't just feel bad mentally. When it becomes chronic, it actively damages your body by weakening the immune system, straining the cardiovascular system, and worsening conditions like asthma and headaches. Understanding these connections is a core part of health psychology.

Chronic Stress and the Immune System

Your body's stress response is designed for short-term threats. When stress becomes chronic, the system stays activated in ways that backfire.

Cortisol is the main stress hormone to know here. In short bursts, it's helpful. But when cortisol stays elevated over weeks or months, it suppresses the immune system by:

• Decreasing production of white blood cells (leukocytes) that fight infection
• Reducing the inflammation response your body uses to heal injuries and fight pathogens like bacteria and viruses
• Diverting energy and resources away from immune function toward dealing with the perceived threat

This weakened immune state makes you more vulnerable to illness in several ways:

• Higher rates of viral infections like the flu and common cold. A well-known study by Sheldon Cohen found that people under chronic stress were significantly more likely to develop a cold after being exposed to the virus.
• Slower wound healing and recovery from injury or surgery
• Increased risk of autoimmune disorders, where the immune system malfunctions and attacks healthy tissue (e.g., rheumatoid arthritis, lupus)

The field that studies these connections is called psychoneuroimmunology (PNI), which examines how psychological processes, the nervous system, and the immune system interact.

Depression, Anger, and Cardiovascular Disease

Depression and cardiovascular disease have a bidirectional relationship, meaning each one can cause or worsen the other.

Depression → Heart Disease:

• Depressed individuals have higher rates of heart attacks (myocardial infarction) and strokes
• Depression reduces motivation for healthy behaviors like exercise and balanced eating, which compounds the risk

Heart Disease → Depression:

• Physical limitations and decreased quality of life contribute to depressive symptoms
• Inflammatory processes involved in heart disease (such as atherosclerosis) may also play a role in depression itself

Anger and hostility are separate but equally important risk factors for cardiovascular disease:

• Outbursts of anger trigger acute stress responses that strain the heart. Anger causes sudden spikes in heart rate, blood pressure, and stress hormones like adrenaline and cortisol. In vulnerable individuals (elderly people, those with pre-existing heart disease), these spikes can actually trigger a heart attack or stroke.
• Chronically angry and hostile people tend to have higher resting blood pressure and heart rate, putting them at greater long-term risk for hypertension and heart disease.
• Hostility also tends to erode social relationships, leading to more isolation and less emotional support, which further increases disease risk.

Psychological Factors in Asthma and Headaches

Stress and Asthma:

Stress is a well-documented trigger for asthma attacks. Here's the mechanism:

1. Stress activates the sympathetic nervous system and triggers release of hormones like cortisol and epinephrine.
2. These stress responses cause airways to constrict and become inflamed.
3. The constriction and inflammation make it harder to breathe, producing wheezing and shortness of breath.

On top of that, chronic stress suppresses the immune system, which increases susceptibility to respiratory infections (bronchitis, pneumonia) that worsen asthma symptoms further.

Stress and Headaches:

Tension headaches and migraines are both triggered or worsened by stress, but through somewhat different pathways:

• Tension headaches result from sustained muscle tightness, especially in the head, neck, and shoulders. They're typically described as a tight band of pressure around the head. Stress directly causes this muscle tension.
• Migraines involve severe throbbing pain, often with nausea and sensitivity to light and sound. Negative emotions like anxiety and depression are common triggers. The exact mechanism isn't fully understood, but it likely involves neurotransmitter imbalances (particularly serotonin).

For both types, stress management techniques can help with prevention:

• Relaxation techniques like deep breathing and progressive muscle relaxation
• Behavioral strategies like better time management and assertiveness training
• These approaches work because they reduce the chronic muscle tension and physiological arousal that trigger headache episodes