ANN ARBOR—New research by a team of researchers from the University of Michigan School of Nursing confirms what health-care professionals suspected about depression: it inhibits short-term memory and directed attention, or concentration.

Up until now, researchers who study depression, and therapists and physicians who treat people with depression, did not have a sensitive measure to assess the subtle changes in memory or attention in the early stages of depression in patients. Yet patients regularly complain of having memory problems and having difficulty concentrating. U-M researchers were interested in learning more about memory and attention impairments in depressed patients. When do the symptoms strike? What are the early signs?

“Prior to this study, my colleague Bonnie Hagerty and I conducted a study that examined the early signs of depression. We were struck by the number of people who said that one of their earliest symptoms was lack of concentration. One of the clients said that she knew she was getting into trouble with another episode of depression when she began to make a lot of errors in her checkbook,” said Reg. A. Williams, a U-M associate professor of nursing who is senior author of the study that appears in the May issue of the Journal of Psychiatric Research. The study is co-authored by Hagerty, a U-M associate professor of nursing who specializes in depression.

The research is based on a series of computer-based and written tests. The tests measured directed attention—which is the ability to focus on the task at hand—and short-term memory, the ability to recall an event that happened within two minutes.

The researchers studied 52 people over a 10-week period. There were 25 people in the group diagnosed with depression and 27 in a comparison group of people without depression. They took five written tests and six computerized tests that were given three times over the course of the study.

Of the 25 in the depressed group, 12 were receiving drug therapy and counseling, while 13 managed their symptoms by relying on self-administered stress reduction techniques, such as yoga or an herbal remedy.

Some of the test results clearly showed memory and attention impairments.

In a computer-based test that measured ability to balance a checkbook, 67 percent of the depression group made errors at the start of the study compared with 48 percent in the comparison group. By the end of the study, both groups made the same number of errors, which, Williams said, clearly indicated progress.

All test scores for those in the depression group improved over time, which Williams attributes to the lifting of depression under drug therapy and counseling. However, he also noted that depressed clients worked harder to compensate for memory and attention impairments. Their desire to succeed—even under the cloud of depression—didn’t affect their desire to perform well.

In scientific terms, having difficulty with short-term memory and concentration are often considered prodromal signs of depression, or early signs of depression. The symptoms can suddenly creep up on people, most of whom don’t recognize them as precursors of depression.

“Our findings reinforce the fact that depression is an illness and not a character flaw or a weakness. It affects your ability to think. When you suffer from depression, people think it just affects your mood. Our study clearly shows it does more than that: It affects your cognitive ability,” said Williams.

The study was funded by the U-M’s Center for Enhancement and Restoration of Cognitive Function and the U-M School of Nursing.

Other co-authors include:

•Bernadine Cimprich, Ph.D., R.N., associate professor of nursing who specializes in directed attention.

•Barbara Therrien, Ph.D., R.N., associate professor of nursing specializing in neuroscience.

•Research assistants Esther Bay, M.S.N., R.N., and Hiroaki Oe, M.S.

School of NursingBonnie HagertyCenter for Enhancement and Restoration of Cognitive FunctionBernadine CimprichBarbara Therrien