Depression Health Center

How Depression Affects Your Body

Depression is a brain disorder that can lead to much emotional anguish. Changes in your brain chemistry also can have a big effect on your body. Is it any wonder, then, that depression contributes to a wide array of physical problems that affect everything from your heart to your immune system? 

Depression doesn't just cause physical symptoms; it can also increase your risk for -- or may worsen -- certain physical illnesses or conditions. In turn, illness can also trigger depression.

Depression Causes Physical Symptoms

Depression affects much more than moods. These are a few of the most common physical symptoms of depression:

• Increased aches and pains, which occur in about two out of three people with depression
• Chronic fatigue
• Decreased interest in sex
• Decreased appetite
• Insomnia, lack of deep sleep, or oversleeping

What causes these symptoms of depression? Changes in the brain have an effect on many of the body's systems. For example, low levels of brain messengers (neurotransmitters) such as serotonin can alter your pain threshold. This means you become more sensitive to pain, especially back pain. Serotonin also affects sleep and lowers sex drive -- nearly half of everybody with depression has problems with sex.

Unfortunately, individuals with depression, as well as their families and health care professionals, often overlook the physical signs and symptoms of depression. In one case, researchers found that sleep troubles, fatigue, and worries about health are reliable indicators of depression in older adults. But, they found, these signs are routinely dismissed as simply a natural part of aging.

Depression Increases Your Risk of Physical Illness

Depression increases your risk of disease and other conditions by, for example, increasing levels of stress hormones such as cortisol or adrenaline.

Depression can affect the immune system, making it harder for your body to fight infection. Vaccinations are even less effective in people with depression.

Depression has also been linked to heart disease and increased risk for substance abuse.

Depression and Medical Illnesses: A Vicious Cycle

Many of the physical changes caused by depression, such as insomnia or a lack of deep sleep, are thought to weaken your immune system. This can make existing illnesses worse. In turn, physical changes caused either by depression or chronic disease can trigger or worsen depression. All these changes can lead to a vicious cycle that's tough to break without treatment for both depression and any other diseases.

Many serious illnesses or conditions coexist with depression. They include:

• Heart attack
• Coronary artery disease (without heart attack)
• Parkinson's disease
• Autoimmune diseases such as multiple sclerosis or lupus
• HIV/AIDS
• Stroke
• Cancer
• Diabetes
• Kidney disease
• Arthritis

Depression increases the risk of some of these diseases, but not always. For example, there is no evidence to support the idea that depression leads to cancer, although the two often coexist. At the same time, it's important to know that depression is not an inevitable result of serious diseases such as cancer and HIV, or that it can't be managed.