One in three adults who have arthritis also have anxiety or depression, according to researchers from the Centers for Disease Control and Prevention.
And anxiety is nearly twice as common as depression among people who suffer from arthritis, which is the leading cause of disability in the United States.
"What we ultimately took away is that we've usually thought of arthritis as a condition that can have such profound disabling consequences," said study author Dr. Louise Murphy of the CDC's arthritis program. "But what came out here is how profound the emotional consequences are. This is a call to action."
In the new study, published Monday in the journal Arthritis Care and Research, Murphy and her co-investigators looked at more than 1,700 adults, age 45 and older, who had been diagnosed with arthritis or other rheumatic conditions; these conditions included osteoarthritis, the most common joint disorder. The study participants were given questionnaires to determine their emotional well-being.
More than one-third said they had at least one of two mental health conditions: anxiety and depression. Anxiety was far more common than depression among the study participants, however. This, according to researchers, was unexpected.
"The proportion of people with anxiety was almost twice as high as [the amount with] depression," Murphy said. "That was a surprise because both in the clinical world and among arthritis researchers, there's so much more attention paid to depression."
Prior research had established a link between chronic pain and depression, although groups like the National Institute of Mental Health caution that the exact, underlying links are not yet fully understood.
The relationship between anxiety, depression and chronic pain is "complex," the authors of the new study agreed, writing that each acts both independently and synergistically as a risk factor for the others.
"When people start living with [arthritis] and the potential limitations it imposes, that can cause distress," Murphy said. The CDC estimates that 21 million of the 50 million adults in the United States currently living with arthritis have some limitation in their activity, including physical or work-related ones, and, in many cases, both.
People with many arthritis may be very hesitant to exercise or simply get out and do things, which can contribute to a general sense of anxiety as well as feelings of depression, Murphy said.
"It makes perfect sense," said Dr. Eric Gall, interim director of the University of Arizona's Arthritis Center.
"These people have chronic pain, and that breeds depression," Gall said. "They're frightened about the disease, they're frightened about being crippled and not being able to do things. They have problems with their marriages and jobs and so forth." Many clinicians and researchers might have focused on the link between arthritis and depression rather than on anxiety, in part, because they often think of anxiety as simply accompanying depression, he said.
Regardless of whether they have depression, anxiety or both, many arthritis sufferers might not be getting help.
More than half of the respondents with anxiety, depression or both had not sought help in the past year, according to the new study. The authors cautioned that the numbers might be underestimated in the current research because they used a conservative definition of depression.
"Health care providers can make an important difference by screening all people with arthritis for anxiety and depression," Murphy said. "We need to be addressing arthritis on a broader basis."