Clinical depression is a serious and often complex medical condition, affecting about 16 million people in the United States.

A report from the National Center for Health Statistics shows that from 2011-14, about 13 percent of people 12 years and older reported taking an antidepressant in the previous month — a number that has increased from 11 percent in 2005-08. In 2015, antidepressants were the second-most commonly prescribed medications after drugs to lower cholesterol.

Research on chronic illnesses and depression indicates that depression rates are high among patients with chronic conditions. In fact, depression is approximately two to three times more common in patients with a chronic physical health problem than in otherwise healthy people.

However, there are some risk factors directly related to having another illness. For example, conditions such as Parkinson's disease and stroke cause changes in the brain. In some cases, these changes may have a direct role in depression. Illness-related anxiety and stress can also trigger symptoms of depression.

Research suggests that people who have depression and another medical illness tend to have more severe symptoms of both illnesses. They may have more difficulty adapting to their co-occurring illness than patients who do not also have depression.

The effectiveness of antidepressants in patients with chronic health conditions has been a topic of debate, and many patients have found that antidepressants do not work. In fact, experts with the O'Donnell Brain Institute point to existing evidence that should prompt healthcare professionals to change their approach to treating depression in the millions of patients with chronic medical diseases.

According to the United States Renal Data System, chronic kidney disease (CKD) affected 15 percent — 48.4 million — of the 322.7 million people in the U.S. in 2016. Up to 25 percent of CKD patients also suffer from depression, many of whom routinely received treatment with selective serotonin reuptake inhibitors (SSRIs). The incidence of depression in this patient group is four times that of the healthy adults.

In a recent study, Dr. Madhukar Trivedi, director of the Center for Depression Research and Clinical Care, part of the Peter O'Donnell Jr. Brain Institute at the University of Texas (UT) Southwestern Medical Center, and colleagues found that patients with CKD did not benefit from a common antidepressant, supporting other research of antidepressant ineffectiveness in patients with asthma and congestive heart failure.

The investigation, based at UT Southwestern and two other Dallas healthcare institutions, involved 193 participants with nondialysis-dependent CKD. The randomized, double-blinded, placebo-controlled 12-week trial evaluated sertraline compared with placebo for depression symptoms in patients with CKD who had not yet started dialysis or received a kidney transplant.

Results were not encouraging. Those who took sertraline for 12 weeks did not significantly improve compared to placebo-treated patients. Although chronic diseases and depression have been linked in previous studies, this is the first time that patients with both CKD and depression have participated in a study of this magnitude.

According to Trevedi, physicians and their patients should be prepared to try alternatives when routine monitoring of symptoms and side effects indicate the need for other strategies, including ketamine, electroconvulsive therapy, neuromodulation with magnetic stimulation, psychotherapy and exercise.