Oct. 28, 2009
Study: depression can lead to inflated reports of physical symptoms
New research shows people who feel depressed tend to recall having more physical symptoms than they actually experienced. The study indicates that depression -- not neuroticism -- is the cause of such over-reporting.
Psychologist Jerry Suls, professor and collegiate fellow in the University of Iowa College of Liberal Arts and Sciences, attributes the findings to depressed individuals recalling experiences differently, tending to ruminate over and exaggerate the bad.
Published electronically this month in the journal Psychosomatic Medicine, the study was conducted by investigators in the UI Department of Psychology, the Center for Research in the Implementation of Innovative Strategies in Practice (CRIISP) at the Iowa City VA Medical Center, and the UI College of Nursing.
The 109 study participants, all female, completed baseline surveys to assess their levels of neuroticism and depression. Each day for three weeks, they reported whether they felt 15 common physical symptoms including aches and pains, gastrointestinal and upper-respiratory issues. On the 22nd day, they were asked to remember how often they had experienced each physical symptom in the preceding three weeks. People who scored higher in depression were more likely to overstate the frequency of their past symptoms.
"People who felt depressed made the most errors when asked to remember their physical symptoms," Suls said. "They tended to exaggerate their experience."
Past research has indicated that people high in neuroticism, a general disposition that includes negative affects like irritability, sadness, anxiety and fear, are more likely to exaggerate their physical symptom experience. This new study indicates that depression -- which can be one component of neuroticism -- is more likely the reason.
"For 30 years, the hypothesis has been that neuroticism is behind inflated reports of symptoms. We're saying no -- depression appears to be the big player," Suls said. "We discovered that people high in neuroticism but low in depression are not likely to misremember symptoms."
Knowing depression has physical symptoms of its own, researchers employed a key control in the study. When looking at the accuracy of symptom recall, they factored out the physical symptoms associated with depression, like changes in sleep and appetite. They also classified participants as depressed or non-depressed based only on the cognitive symptoms of depression, such as sadness and anhedonia, a lack of interest in normally pleasurable activities. Depressed individuals still over-reported physical symptoms.
The topic is important, Suls said, because inflated symptom reports skew the information healthcare providers need to determine the best course of action. Perception of symptoms can also affect the patients' decisions -- such as whether they take time off work, use over-the-counter medications, or see a doctor.
"Depressed individuals and their physicians shouldn't discount common symptoms because they can indicate serious problems," Suls said. "However, since we now know that depressed individuals tend to over-remember the frequency of symptoms, it wouldn't hurt to encourage patients to write down their symptoms as they're happening. That way the patient and doctor have an accurate record of what has been going on, rather than relying on memory."
This particular study focused on women, but Suls and colleagues are examining results for a mixed group of men and women. Participants in the studies were in good health overall. In the future, Suls would like to investigate how depression affects symptom reporting in individuals with chronic illnesses.
The research was supported by a grant to Suls from the National Institute on Aging. Co-Authors of the paper are M. Bryant Howren, now a post-doctoral fellow with CRIISP at the VA Medical Center in Iowa City, and René Martin, a research health science specialist at CRIISP and an associate professor in the UI College of Nursing. CRIISP is funded through the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development.
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