Shadow Diseases: 5 Health Conditions That Have a Secret Twin

Could itchy skin put you at higher risk for heart disease? Yes--researchers are finding more and more about the connections between seemingly unrelated health conditions. Called “shadow diseases,” these are health problems that go hand-in-hand: If you have one, your risk increases for developing the other.  “The connection may come from your genetic makeup, or as a reaction to your environment and lifestyle, so both nature and nurture play a part,” says Alicia Almeida Ponce, MD, a family doctor at Indiana University Health. “While these studies are very interesting, they don’t prove you will absolutely get one disease if you have another,” she adds. “Think of it as a red flag to talk to your doctor and try to modify other lifestyle factors to lower your risk.”

Migraines and heart attack/stroke: Several studies have found a connection between migraines—debilitating headaches that are accompanied by symptoms such as nausea and light sensitivity—and heart attack or stroke. The more frequently you have migraines, the greater the risk for heart disease, and if you experience aura (flashing lights or dots as the headache comes on), your risk goes up as well. A recent study in the journal Neurology Genetics, however, found no genetic connection between the two diseases, suggesting that lifestyle factors associated with migraines, such as obesity, smoking, and lack of exercise, may be primarily responsible for the higher risk of heart diseases.

Celiac and thyroid disease: People with the autoimmune disease celiac (which causes the body to attack the small intestines any time they eat gluten) are up to four times more likely to develop a thyroid condition such as Hashimoto’s or Graves’ disease, in which the butterfly-shaped organ responsible for metabolism either produces too much or too little hormone. It’s important for those with celiac to have their thyroid-hormone levels checked and get treatment if necessary.

Psoriasis and diabetes/heart disease: Red, itchy, flaky skin would seem to have little to do with your cardiovascular system, but both psoriasis and heart disease and are inflammatory diseases, explains Dr. Almeida Ponce. One large study found that people with severe psoriasis had a 6.2 percent higher chance of having a major cardiac event (stroke or heart attack) within ten years, and another recent study found that children with psoriasis had greater risk factors for both heart disease and diabetes. Obesity is one of the main risks linking all three conditions, so talk to your doctor about a healthy weight-loss plan.

Asthma and depression: Approximately 26 million Americans have chronic asthma, which restricts their airways, causing trouble breathing; those people are as much as twice as likely to suffer from depression, possibly because of the stress of living with a chronic illness. Conversely, one study found that women who were depressed had a higher risk of developing adult-onset asthma. While more research is needed to tell which condition causes which, treating your depression with talk therapy or antidepressants if needed, and managing your asthma so you can do things that lift your mood—like exercising and going out with friends—can help.

Endometriosis and melanoma: It seems logical that women who suffer from endometriosis (a painful condition in which the uterine lining grows in other places, such as the Fallopian tubes and ovaries) would have a higher risk of uterine cancer, but two large studies in France and Sweden also found a strong link between the disease and melanoma, the deadliest form of skin cancer, pointing to a genetic connection between the two diseases. Thankfully, if melanoma is found early (before it spreads to lymph nodes or other organs), it has a 98 percent survival rate. If you have endometriosis—and even if you don’t!—stay out of the sun and see your dermatologist for annual skin checks.

-- By Marisa Cohen