CHAPTER 13

The Depression Cascade

PART 1 Cascading Illness

Depression isn’t all in your head—it has major physiological effects on all of your body’s major systems and increases the likelihood of developing many major diseases. Having a depressive disorder unleashes a cascade of harmful effects on your body.

PART 2 Depression and the “Stress Hormone”

Being depressed alters your normal levels of cortisol, a hormone produced by your adrenal gland.

Cortisol is sometimes called the “stress hormone.” When your body is under stress or a threat is perceived, cortisol helps you to mobilize for action—the “fight or flight” reaction. One of cortisol’s functions is to suppress your immune system (healing is not a big priority when facing an immediate danger). Cortisol also increases blood sugar for quick energy, raises blood pressure, and decreases bone formation. READ MORE

All these effects are normal, and necessary, when you are in a perilous situation. Problems start when the effects of cortisol become chronic instead of temporary. Cortisol levels tend to be erratic, but normally they peak in the morning and decrease as the day progresses. However, in people with depression, cortisol levels peak earlier in the morning and don’t level off or decrease in the afternoon or evening. LESS

PART 3 The Damage Cortisol Does

Researchers think that altered cortisol levels may have many damaging effects. Chronically high cortisol levels may affect levels of serotonin, bringing on or worsening depression. Suppression of bone formation may lead to osteoporosis. Hypertension (chronically heightened blood pressure) and high blood glucose levels can lead to abnormal cholesterol and triglyceride levels, diabetes, atherosclerosis, heart disease, stroke, and kidney disease.

PART 4 Depression and Heart Disease

Research Report

Can smiling protect your heart?

It’s long been known that there is a strong connection between heart disease and depression. Even healthy individuals who suffer from depression are at significantly increased risk of developing heart attacks and strokes later in life. Between 17% and 27% of patients hospitalized with coronary artery disease (CAD) have major depression. READ MORE

It’s not clear exactly what the connection between depression and heart disease is, but Dr. Philip Gold, chief of clinical neuroendocrinology at the National Institute of Mental Health, thinks he has a clue. One effect of having chronically high blood glucose levels is craving carbohydrates and starches. According to Gold, these high-glycemic-index foods are key players in altering normal blood lipid levels, creating inflammation, damaging arteries and capillaries, and leading to heart disease. LESS

PART 5 Depressing the Immune System

Cortisol’s continued suppression of the immune system puts you at risk for a number of diseases because your weakened immune system may not be able to successfully rid your body of pathogens. Just a 20-minute episode of stress has been shown to reduce natural killer cell activity for up to 3 days. Even vaccinations are less effective in people with depression. Other physical changes caused by depression, such as lack of restful sleep, further weaken your immune system.

PART 6 Not Taking Care

Another important factor in the association between depression and other diseases is lack of self-care. People who become depressed often stop taking care of themselves. They may stop taking prescribed medications for conditions like high blood pressure or diabetes, they may eat poorly, and they often become physically inactive. New disorders can develop because of this and existing conditions can get worse. Lack of self-care may explain in part why people with depression have a higher risk of death following a heart attack.

PART 7 Harder to Treat Down the Line

As the downward cascade of illness continues, it becomes harder and harder to treat conditions. For instance, if you catch hypertension early on, you may prevent damage to the kidneys. Once the damage is done, however, the kidneys can’t repair themselves. As another example, if you eat well and exercise, you may prevent damage to your cardiovascular system. But further down the cascade, when you have developed heart disease, heightened levels of cortisol may keep your tissues from repairing themselves.

PART 8 Other Disorders

Numerous other disorders are associated with depression, but there may be no clearcut cause-and-effect relationship. Associated disorders include Parkinson's disease, autoimmune diseases such as multiple sclerosis and lupus, HIV/AIDS, cancer, and arthritis.