Multiple prior studies have found higher levels of inflammation in older individuals with depression. Now, a new Penn Medicine study has found that clinically depressed older individuals, on average, don’t have elevated levels of inflammation if they don’t already have other inflammatory conditions such as arthritis.
The study, published in Nature Translational Psychiatry, suggests that depression occurs independently of inflammation for many older adults. Furthermore, depression-inflammation links are due to the greater incidence of inflammatory conditions, which in general are common in older people.
“It is still true that inflammatory illnesses can contribute to depression, but our findings suggest that there is a subset of individuals with late-life depression who do not have elevated levels of inflammation,” says study senior author Yvette Sheline, McLure Professor of Psychiatry and Behavioral Research in the Perelman School of Medicine.
National surveys in the United States suggest that, although depression is diagnosed more often among younger adults, about 5% of people who are at least 50 years old have had a major depressive episode in the past year. Researchers suspect that many of these cases of late-life depression are caused by inflammation—in part because studies have found higher levels of inflammatory immune proteins in the blood of older people with depression, compared to non-depressed people of the same age.
Prior research also has shown that levels of inflammation markers generally tend to rise with increased age, as chronic illnesses set in and the body’s immune-regulating systems weaken. Based on such findings, doctors have tested anti-inflammatory drugs in patients with depression, and have found that they can improve outcomes when added to standard anti-depressant therapy.
The new study reveals, however, that the link between depression and inflammation is not as clear-cut as the prior literature suggests.
Read more at Penn Medicine News.