Depressive thoughts don't just make you down in the dumps. Apparently they also negatively affect your working memory, new research shows.

It was already known that dysphoric individuals (DIs) and clinically depressed people can pay attention to "mood-congruent" information longer than those who aren't depressed. Dysphoria is defined as a significant and prolonged depressed mood related to clinical depression.

Lead researcher Nicholas A. Hubbard and his colleagues built on this knowledge and carried out three studies to test both working memory and processing speed. The results were published in the journal Cognition and Emotion.

The first experiment involved a recall task with "neutral" interference, while the second was a variation of the first with "depressive" interference - meaning the researchers gave participants negative statements about their mood.

Lastly, the team repeated these experiments and focused on processing speed and recall.

It turns out there was no real difference between DI and non-DI working-memory capacity in the first study. However, when "depressive" interference was thrown into the equation, the results were vastly different.

DIs were unable to repress the negative thoughts they were confronted with, and this consequentially seemed to reduce the amount of working memory they had available for the recall task.

"Results from these studies imply that mood-congruent information evokes controlled attention deficits in individuals with depressed mood," the authors concluded. "If mood-congruent information is not able to be efficiently removed from the focus of attention, we would expect this to result in a relative decrease in working-memory capacity for individuals with depressed mood compared to those without depressed mood."

Difficultly concentrating and remembering day-to-day goings on are symptoms of both clinical depression and dysphoria. By better understanding the link between these two factors, researchers may be able to improve overall wellbeing of these types of patients.

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