Also: Can digital fitness trackers get you moving; Which medications are best for depression?

Depression and illness: Chicken or egg? When depression strikes, doctors usually probe what's going on in the mind and brain first. But it's also important to check what's going on in the body, since certain medical problems are linked to mood disturbances. In fact, medical illnesses — and medication side effects — may be behind nearly 10% to 15% of all cases of depression. It's not uncommon for a physical illness to trigger depression. Up to half of heart attack survivors and those with cancer report feeling blue, and many are diagnosed with depression. Many people who have diabetes, Parkinson's, or other chronic conditions become depressed. Get your copy of Understanding Depression Depression is more than a passing bout of sadness or dejection, or feeling down in the dumps. It can leave you feeling continuously burdened and can sap the joy out of once-pleasurable activities. Effective treatment can lighten your mood, strengthen your connections with loved ones, allow you to find satisfaction in interests and hobbies, and make you feel more like yourself again. It works in the other direction, too. Depression can affect the course of a physical disease. Take heart disease — depression has been linked with slower recovery from a heart attack and an increased risk for future heart trouble. Here's another chicken-or-egg example. Two common thyroid disorders are well known to affect mood. If the thyroid makes too much hormone (hyperthyroidism), manic symptoms can result. If the gland makes too little thyroid hormone (hypothyroidism), exhaustion and depression can appear. Treating thyroid disease can often relieve the mood problems. The list doesn't stop there. Other medical conditions associated with mood disorders include certain neurological conditions (multiple sclerosis, Parkinson's disease, Alzheimer's), other hormonal imbalances, and some nutritional deficiencies, such as a lack of vitamin B12. The take-home message is that if you have depression, or think you might, a thorough physical exam and careful medical history could help pinpoint a physical source of the problem — and the most appropriate treatment. For more on diagnosing and finding the right treatment on the different types of depression, buy Understanding Depression, a Special Health Report from Harvard Medical School. Share this story: News and Views from the Harvard Health Blog Can digital fitness trackers get you moving? Study after study has shown that Americans don't get enough activity. In fact, many of us don't even get our recommended 10,000 steps a day. In a small study published in the American Journal of Preventive Medicine, researchers gave either a standard pedometer or a Fitbit brand digital fitness tracker to 51 overweight postmenopausal women who had been getting about 33 minutes per week of moderate to vigorous physical activity. The Fitbit group increased their physical activity by 38 minutes per week. Medications for depression: Which is best? One day, a detailed knowledge of the biology of depression may help us to predict which antidepressant will work best for each person. Right now, though, psychiatrists and other doctors who prescribe antidepressants choose a particular drug and dosage based on many factors, including the following: Diagnosis. Certain drugs work better for specific symptoms and types of depression. For example, some antidepressants may be better than others when insomnia is an issue. Side effects. Ask your doctor about the side effects of the recommended antidepressant. If common side effects are things you want to avoid, see if there is another option. Age. As you age, your body tends to break down drugs more slowly. Thus, older patients may need a lower dosage. Only a few depression medications have been studied carefully for use in children. Health. Your doctor will consider factors such as heart disease or neurological illnesses when recommending a particular antidepressant. Be sure to discuss any medical problems thoroughly with your primary care doctor or psychiatrist before starting an antidepressant. Medications, supplements, and diet. When combined with certain drugs or substances, antidepressants may not work as well or may even have worrisome or dangerous side effects. People taking an antidepressant known as a monoamine oxidase inhibitor (MAOI) need to take particular care. Alcohol or drugs. Alcohol and other substances can cause depression and make antidepressants less effective. Doctors often treat alcohol or drug addiction first if they believe either is causing the depression. In many instances, simultaneous treatment for addiction and depression is warranted. Once you have learned as much as you can about the treatment options, talk to your doctor about the approach that seems best for you given your lifestyle, your interests, and your judgment. For additional information on medications and their effectiveness, buy Understanding Depression, a Special Health Report from Harvard Medical School. Share this story: Featured in this issue Understanding Depression Featured content: • What is depression? • Causes of depression • Diagnosing depression • Seeking treatment • Finding the right medication •  ... and more! Click here to read more » Harvard Medical School offers special reports on over 50 health topics. Visit our website at http://www.health.harvard.edu to find reports of interest to you and your family. 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