By John Salak –
Depression is not only extremely harmful, but its impact can also linger well after the dampening moods have appeared to pass on. In fact, people who have recovered from a major depressive episode tend to spend more time processing negative information and less time processing positive information than those who have never confronted a significant episode. This negative processing ultimately puts them at risk for a relapse, according to new research.
The findings are significant since depression is a leading mental health issue in the U.S. It is estimated that almost 40 percent of women and about 20 percent of men have suffered from depression at least once during their lives. The National Institute Of Mental Health noted that more than 20 million Americans, about 8 percent of the population, have suffered a major depressive episode, which this new research claims puts them at even greater risk of a relapse.
“Our findings suggest that people who have a history of depression spend more time processing negative information, such as sad faces, than positive information, such as happy faces, and that this difference is greater compared to healthy people with no history,” said Alainna Wen, Ph.D., the study’s lead author and a postdoctoral scholar at the Anxiety and Depression Research Center at the University of California, Los Angeles. “Because more negative thinking and mood and less positive thinking and mood are characteristic of depression, this could mean that these individuals are at a greater risk for having another depressive episode.”
Defined as a period of at least two weeks of a depressed mood or loss of interest or pleasure in daily activities, major depression can interfere with or limit a person’s ability to carry out major life activities.
Treatments are available, but relapse rates for major depressive disorder remain high. Wen notes that more than half of these individuals will experience subsequent episodes, often relapsing within two years of recovery. These relapse rates encouraged Wen and her team to dive more deeply into the causes.
The researchers tackled the challenge by conducting a meta-analysis of 44 studies involving 2,081 participants with a history of major depressive disorder and 2,285 individuals who were deemed as healthy controls. The data examined participants’ response times to negative, positive or neutral stimuli. In some cases, participants were shown either a happy, sad or neutral human face and asked to push a different button for each. In others, participants reacted to positive, negative or neutral words.
Healthy participants as a group responded more quickly to emotional and non-emotional stimuli than participants with a history of depression, regardless of whether those stimuli were positive, neutral or negative. But participants who previously had major depressive disorder spent more time processing negative emotional stimuli over positive stimuli compared with those identified as healthy controls. These “more positive” individuals showed a significant difference in how much time they spent processing positive versus negative emotional stimuli compared with those in remission from major depression. This distinction did not appear when comparing time spent processing negative versus neutral or positive versus neutral stimuli.
The research suggests that individuals with recurrent major depressive disorder not only are less able to control the information they process than healthy individuals, but they also display a greater bias for focusing on negative over positive or neutral information, Wen reported.
“The current findings have implications for the treatment of depression,” she said. “Focusing on reducing the processing of negative information alone may not be sufficient to prevent depression relapse. Instead, patients may also benefit from strategies to increase the processing of positive information.”