Young adults with recurrent depression experience processing speed deficits that are not affected by symptom severity, and the interaction between recurring episodes of depression and aging appears to exacerbate cognitive performance deficits with each recurrence, according to a study published in Depression and Anxiety.
The study included 196 participants between the ages of 20 and 50 who were enrolled at Vanderbilt University Medical Center and Duke University Medical Center, with 91 adults in the antidepressant-free depressed group and 105 in the never-depressed control group.
The study’s objective was to examine the impact of early onset recurrent depression untreated by antidepressants on cognitive performance, including executive function, episodic memory, working memory, and processing speed. The interactive effects of age and duration of depression on cognitive performance were also examined.
Comparisons between the 2 study groups showed that the depressed adults scored significantly poorer in processing speed (F1,189= 4.82, P =.0294) compared with non-depressed adults. There were no group differences observed for working memory (F1,189= .18, P =.6753), episodic memory (F1,189=3.78, P =.0533), or executive function (F1,189=2.96, P =.0522). Analysis of the effect of age and depression duration on cognitive performance found significant interaction between these factors on executive function (F8,64=4.98, P =.0291) and processing speed (F8,64=10.96, P =.0021), but not on episodic or working memory.
Study investigators conclude that the study’s findings suggest that the cognitive domain most negatively affected by depression is processing speed, but the degree of impact is not related to the severity of depressive symptoms. This suggests that slowed processing speed may be a consequence of depressive disorder or related to increased risk for depression but is not an indicator of present mood dysregulation. “Future work should include neuroimaging methods that may reveal alterations in brain activity or functional connectivity that may maintain cognitive performance in depressed younger adults as well as assessments in remitted or at risk depressed individuals to further define the role of processing speed reduction as a risk factor or trait consequence of depression.”
Albert KM, Potter GG, McQuoid DR, Taylor WD. Cognitive performance in antidepressant‐free recurrent major depressive disorder [published online April 10, 2018]. Depress Anxiety. doi: 10.1002/da.22747