The Role of Cognitive Deficits in Vulnerability to Depression and Anxiety: An Individual Differences and Neuroimaging Approach

Abstract

Mood and anxiety disorders are heterogenous disorders that display complex symptom presentations. While cognitive deficits have been demonstrated in meta-analyses of currently depressed individuals (Snyder, 2013), a number of questions remain as to the role of cognitive deficits in depression. Given ongoing debates about whether the FDA should approve drugs to treat cognitive deficits associated with depression (Ledford, 2016; Mullard, 2016), it is essential to gain a more complete understanding of the role of cognitive function in the disorder. This dissertation is comprised of three studies that broadly explore the association between cognitive functioning and depressive diagnoses and symptoms. First, I look at the longitudinal relationship between cognitive function and later depression through a systematic review and meta-analysis of the extant literature, “The Association Between Cognitive Function and Subsequent Depression: A Systematic Review and Meta-Analysis.” I find that cognitive function predicts future depressive symptoms and diagnoses, but that this effect is likely driven by depressive symptoms at the time of cognitive testing. The value of a dimensional versus categorical framework for diagnosis is discussed. Next, I investigate this relationship with more precision by studying the association between cognitive function and depression in a well-documented longitudinal dataset. Here, I find that comorbid diagnoses play an important role in moderating the association between cognitive function and depression, “Is Low Cognitive Functioning a Predictor or Consequence of Major Depressive Disorder? A Test in Two Longitudinal Birth Cohorts.” Finally, I look at neural correlates of cognitive function in relation to symptoms of mood and anxiety disorders broadly, “Thinking and Feeling: Individual Differences in Habitual Emotion Regulation and Stress-Related Mood are Associated with Prefrontal Executive Control.” I find that dorsolateral prefrontal activity during a non-emotion-related working memory task is associated with both mood and anxiety symptoms and clinical diagnoses. Additionally, the results suggest that cognitive reappraisal is also associated with this prefrontal activity, indicating a possible mechanism through which cognitive function is related to mood and anxiety symptoms. The results of these studies are discussed in regards to implications for targeting treatments for mood and anxiety disorders.