"The relationship between cognition – thinking, attention and memory – and depression remains poorly understood from a neuroscientific standpoint," said Dr. Munro Cullum, chief of psychology at UT Southwestern and senior author of the review appearing in the January issue of Neuropsychology, a journal published by the American Psychological Association. "This paper represents an important review of the literature that challenges some of the clinical myths about the effects of depression on cognitive functioning."
Part of what contributes to the clinical lore is that difficulties in concentrating can be a symptom of depression, and this may masquerade as other cognitive problems such as variability in memory performance.
"The presentation of depression can vary between people," said Dr. Shawn McClintock, assistant professor of psychiatry at UT Southwestern and lead author of the study. "Many symptoms can be used to diagnose depression, so we tried to dissect and better understand how specific factors in depression might contribute to cognitive difficulties."
Just as a higher fever can indicate more-severe illness, researchers wanted to determine if more-severe depressive episodes led to a greater impairment of cognitive abilities. The reviewers examined 35 studies published between 1991 and 2007 that investigated links between depression severity in patients and specific impairments in their cognition. The areas of cognition included processing speed, attention, memory, language abilities and executive functioning.
"We found a lot of variability between studies that were conducted," Dr. McClintock said. "Some suggested cognitive difficulties; others said there were none."
In the research, processing speed was found to be the cognitive function most often affected by depression. Processing speed refers to an individual's ability to quickly take in information, process and act upon it. The capability slows when some individuals are depressed, the reviewers found. The link wasn't as clear for other types of cognitive abilities, including attention, concentration, memory and executive function.
Researchers found that part of the variability in the literature may be due to inconsistent measurement and diagnosis of depression among studies. Some studies diagnose depression using clinical research criteria, while others use depression severity scales.
"The research has not been the most rigorously controlled," Dr. McClintock said.
The review suggests that researchers need to collect more comprehensive neurocognitive assessment data in patients diagnosed with depression to minimize confounding factors such as age and education. The researchers also recommend that more detailed information be collected about each depressive episode, such as its duration and intensity.
"If we do this, clinicians can help a depressed patient with processing speed deficits by decreasing the amount of information a patient has to process at one time, while researchers could work out nuances to discover if we can target cognitive deficits and improve them," Dr. McClintock said.
"Research for the past few decades has been very beneficial, but it has actually provided more questions than answers. We need to take the heterogeneous, nuanced concept of depression and better characterize it, so we can refine future investigations and guide clinical practice."
Other UT Southwestern researchers involved in the study were Dr. Mustafa Husain, professor of psychiatry and internal medicine, and Dr. Tracy Greer, assistant professor of psychiatry.
Visit www.utsouthwestern.org/neurosciences to learn more about UT Southwestern's clinical services in neurosciences, including psychiatry.
This news release is available on our World Wide Web home page at www.utsouthwestern.edu/home/news/index.html
To automatically receive news releases from UT Southwestern via e-mail, subscribe at www.utsouthwestern.edu/receivenews
LaKisha Ladson | EurekAlert!
Biofilm discovery suggests new way to prevent dangerous infections
23.05.2017 | University of Texas at Austin
Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy