April 18, 2019
A 20-year study of women with lupus has found strong evidence that depression increases a person’s risk of developing lupus. That insight casts doubt on the generally accepted belief that depression is simply a by-product of having lupus. If depression is the chicken and lupus is the egg, the researchers found that the chicken could come first.
Earlier studies made progress in untangling the lupus-depression relationship. They confirmed that many autoimmune diseases often go hand-in-hand with depression. They also found that if a patient already has an autoimmune disease, depression tends to increase its severity.
What makes the current study different is that its authors measured the sequence of events in close to 200,000 women over a 20-year period. They found that the risk of developing lupus was more than double for women with a history of depression than for women with no history of the mood disorder. That number remained the same when a patient’s depressive episode started four years before a lupus diagnosis or if it began closer to the time when the first clear symptoms of lupus appeared.
The number also held steady when the researchers factored in the effects of lifestyle behaviors known to increase inflammation such as smoking and obesity, as well as the effects of race, socioeconomic status, and age at the start of menstruation. None of these potential risk factors changed the data supporting a strong causal relationship between depression and lupus.
The authors hope their findings will help them, and other researchers, clarify whether women who develop lupus have different blood markers than women without the disease. They’re also looking at whether these markers are related to depression.
They also hope that the study’s results will encourage doctors to screen their high-risk patients—women with depression who also have a family history of lupus—as a way of detecting the disease early. With early detection, doctors can help to reduce inflammation in these patients by urging them to make lifestyle changes such as quitting smoking and losing weight. That may help to reduce their risk of developing lupus, as well as other negative health consequences of depression.