Depression doesn’t necessarily lead to cognitive difficulties such as lack of concentration and memory loss, according to new research from the University of Texas Southwestern Medical Center in Dallas that was printed in the January issue of Neuropsychology.

For the study, researchers looked at 35 studies published between 1991 and 2007 that examined the relationship between the degree of depression in patients and their cognitive abilities. Specifically, the areas of cognition ability included: processing speed, attention, memory, language abilities and executive functioning.

The widely held belief is that depressed people usually suffer difficulties these areas, but the scientific review found that this wasn’t necessarily true. According to press information from UT Southwestern, the only link the researchers found was between depression and processing speed, which is a person’s ability to quickly take in information, process it and act on it.

“This paper…challenges some of the clinical myths about the effects of depression on cognitive function,” say Munro Cullum, chief of psychology at UT Southwestern and the paper’s senior author.

The research also found that many of the studies used inconsistent measurements in their diagnosis of depression. “We found a lot of variability between studies that were conducted,” said Shawn McClintock, an assistant professor of psychology at UT Southwestern.

“Research for the past few decades has been very beneficial,” McClintock added, “but it has actually provided more questions than answers. We need to take the heterogeneous, nuances concept of depression and better characterize it, so we can refine future investigations and guide clinical practice.”