Mild sadness provokes depressive thinking in some recovered patients

Some individuals with a history of depression may sink back into thinking patterns associated with the condition when faced with mild stresses or sadness, increasing their risk for relapse, according to a report in the July issue of Archives of General Psychiatry.

Many patients who recover from depression eventually relapse, according to background information in the article. Management of depression usually focuses on alleviating symptoms rather than reducing the risk for recurrence or identifying patients who might relapse after successful treatment. Previous studies have found that some patients who have recovered from depression still show cognitive processes - patterns in thinking, learning and memory - commonly associated with the condition, while others in remission do not. Such cognitive processes include certain ways of explaining events or particular assumptions about self-worth.

Zindel V. Segal, Ph.D., University of Toronto and Centre for Addiction and Mental Health, Ontario, and colleagues randomly assigned 301 patients with major depressive disorder to receive either antidepressant medications or cognitive behavioral therapy (a kind of psychotherapy designed to modify the cognitive processes that are typically associated with depression). Ninety-nine of those whose depression went into remission participated in a second phase of the trial. These 99 participants rated their current mood on a visual scale from sad to happy and underwent an assessment of their dysfunctional attitudes, signs of the cognitive processes that are associated with depression. The researchers then provoked a sad mood by asking participants to listen to a piece of music and try to recall a time in their lives when they felt sad. After this exercise, the participants rated their mood and underwent the dysfunctional attitude assessment a second time and were observed bimonthly for the next 18 months.

Seventy-eight patients completed the full 18 months of follow-up; 47.5 percent of those who had recovered through antidepressant medication use and 39 percent of those who received cognitive behavioral therapy relapsed during that time period. Regardless of the type of treatment, those who had greater cognitive reactivity - that is, they displayed significantly more dysfunctional beliefs after the sad mood provocation than before it - were more likely to relapse during the 18-month follow-up. This association held true even when researchers considered the number of past episodes of depression each patient had experienced, previously the best known way to predict relapse. In addition, those who took antidepressants were more likely to have greater cognitive reactivity than those in the cognitive behavioral therapy group.

"Our study indicates that even a mild negative mood, when experienced by someone with a history of depression, can reinstate some of the cognitive features observed in depression itself," the authors write. "The presence of such reactivity in recovered patients signals a residual but heightened risk for episode relapse that has not been fully addressed by treatment."

Future depression management approaches might aim to help prevent relapse by teaching patients to reflect on the factors that influence their thinking, the authors suggest. "Such treatments may include components that first help patients deliberately monitor and observe their thinking patterns when they feel sad, and then help patients respond to these thoughts and feelings in a way that allows them to inhibit the cognitive elaboration of their content," they write.