Depression increases in some patients with multiple sclerosis over time, according to neuropsychologists, and this research finding could help reduce depression in patients and aid in better treatment strategies.
"Depressed mood in patients with multiple sclerosis changes more significantly over time than other stable depression symptoms such as a negative view of oneself or problems in sleep, fatigue, concentration, and appetite," said Peter Arnett, associate professor of psychology at Penn State.
In addition, data from the tests show that a larger number of patients in the increased depressed mood group were also using interferon beta drugs to slow down progression of the disease, but researchers say it is too early to say whether the drugs might be causing the depression.
"At this point we can only make an inference, but not a causal connection," said Arnett, a faculty member in the College of the Liberal Arts. He published his findings in the current (May) issue of the Journal of Neurology, Neurosurgery and Psychiatry.
Statistical analyses suggest that while symptoms such as negative outlook, sleep problems and concentration remained stable over time, depressed mood changed significantly.
Depression is very common in multiple sclerosis. Around half of all MS patients are diagnosed with clinically significant depression at some time during the course of the disease. This may not only affect patients' cognitive ability but also their daily functions and quality of life, Arnett explained. However, the way in which depression progresses is still unclear because previous studies focused on a single measure of depression, rather than several symptoms such as mood, a negative outlook, and problems with sleep, fatigue, concentration, and appetite.
"We have to understand the characteristics of how depression changes and evolves over time," said Arnett. "A better understanding of the natural history of these changes might help inform better treatment strategies. This is the first study to have done this."
Working with John Randolph of Dartmouth Medical School, Arnett chose 53 patients who were diagnosed with definite or probable multiple sclerosis. Patients were tested twice over a gap of three years to see what effect changes in coping strategies had on the patients' depression, and whether an increase in depression symptoms was linked to interferon beta treatments.
"We found that patients whose depressed mood increased over time also showed a decreased use of actively coping with stress, while patients whose depression decreased were using significantly more active ways of coping," said the Penn State researcher. "We could make an inference that reduced use of active coping causes people to become more depressed, however, we cannot make that connection with certainty, given the methodology we used."
Data from his study indicate that 43 percent of patients with an increased depressed mood were taking interferon beta drugs at both test points, compared to just 13 percent of patients with a decreased depressed mood. In other words, people who increased in their depressed mood were much more likely to be taking interferon beta drugs.
"Once again we cannot prove anything causally, but it warrants some comment that maybe these interferon drugs represent some kind of a risk factor for increased depression," said Arnett.
One implication of the results is that people who have depressed mood might benefit from learning some active coping strategies while in therapy, and thus become less susceptible to increased depression, he added. Second, since negative evaluative symptoms of depression were found to be quite stable over time and unlikely to change easily, targeting them through cognitive-behavioral therapy might prove beneficial.
Physicians, psychologists, and neurologists who are involved in prescribing interferon beta drugs need to be careful about following up and seeing how the patients are doing in terms of their depressed mood, according to the Penn State researcher.
"Suicide is a big risk in MS patients. You certainly wouldn't want to prescribe somebody a drug that might increase that risk without monitoring that person very carefully," he noted.