From high anxiety trait to depression: a neurocognitive hypothesis
From high anxiety trait to depression…
From high anxiety trait to depression: a neurocognitive ..
Major depressive disorder (MDD) is a devastating psychiatric condition of mood dysregulation characterized by disturbance in positive and negative emotional experiences. Elucidating the nature of such disturbance is a necessary step toward clarifying pathophysiology and improving diagnostic, treatment, and prevention efforts. While dysregulated affect is a hallmark of MDD, the nature of such dysregulation remains to be characterized. It has been suggested that MDD is characterized by blunted emotional response not only to positive stimuli , , but, perhaps more surprisingly, to negative stimuli . Indeed, Rottenberg et al proposed the emotion-context insensitivity (ECI) hypothesis, according to which MDD is associated with diminished reactivity to both rewarding and threatening stimuli. Although the ECI hypothesis has recently been supported in a meta-analysis , the hypothesis that MDD shows reduced defensive response is inconsistent with substantial neurocognitive evidence of hyperactive aversive emotional responding , and with the theoretical conceptualization that depression and anxiety disorders share a common distress factor of heightened affective negativity . Such a distress factor leads to an alternative to the ECI hypothesis, the negative potentiation hypothesis , which predicts exaggerated not blunted response to aversive stimuli. The negative potentiation hypothesis is supported by evidence that the amygdala can be hyper-reactive in MDD , together with findings of enhanced fear conditioning in this condition . In addition, high trait anxiety/neuroticism is a vulnerability marker for depression and depressed individuals exhibit substantially high levels of anxiety/neuroticism, which should also lead to exaggerated aversive responding.
The lack of significant task-related asymmetry in a depressed sample in a prior study may have been related to failure to distinguish between depressed patients with high and low trait anxiety levels. While partialling out the effects of anxiety from depression in a healthy sample did not affect the task-related alpha asymmetry, depressed patients having high anxiety in the current study showed different task-related asymmetries when compared to patients with low anxiety and healthy adults. From the current findings, it may be inferred that depressed individuals with low trait anxiety have a tendency toward greater left-hemisphere activity, which in effect maintained the expected task-related asymmetry in the verbal task but reduced it in the spatial task. In contrast, depressed individuals with high trait anxiety have an opposite tendency, which heightened the right hemisphere advantage on the spatial task and decreased the left hemisphere advantage on the verbal task. These results are in line with previous EEG evidence of greater left than right posterior activity in both currently and previously depressed individuals, and a reduction in the normal right hemisphere superiority for face processing in depressed patients. The opposite pattern observed in the high-anxiety depressed patients in the present study is consistent with evidence of greater right that left hemisphere activity measured by dichotic listening studies in patients with comorbid major depressive and anxiety disorders,– opposite patterns of asymmetry in reaction time to lateralized stimuli in depressed versus anxious patients, chimeric face perception studies in individuals grouped according to levels of trait anxiety and depression,, and resting alpha asymmetry at posterior sites in patients with comorbid major depressive and anxiety disorders., While few studies have examined electro-physiological asymmetries associated with cognitive functions, results from this study are also consistent with an ERP study suggesting opposite effects of anxiety and depression in functional asymmetry.
Course Content - #96180: Anxiety Disorders - NetCE
One way to test the hypothesis that depression and anxiety exhibit opposite functional asymmetries in posterior regions is to compare performance and EEG recorded during cognitive tasks which selectively engage the left or the right posterior regions. EEG alpha in healthy adults recorded during a set of matched verbal (Word Finding) and nonverbal (Dot Localization) tasks confirmed greater activation over the left and right hemispheres, respectively. As would be expected given a right posterior deficit, depressed patients show a selective weakness on the Dot Localization task., Further, depressed patients failed to demonstrate the task-specific posterior asymmetries found in controls, instead showing relative left-sided activation during both tasks. Relative right hemisphere hypoactivation during the spatial task was also associated with higher levels of depression in college students, both before and after partialling out level of anxiety. However, a study of men having a depressive disorder using the Word Finding and Dot Localization tasks reported finding left frontotemporal hypoactivation. Conflicting findings for depressed patients could arise from the failure to take into account comorbid anxiety disorders, or methodological differences across studies, e.g., in the reference electrode.
Studies of regional hemispheric asymmetries point to relatively less activity in left frontal and right posterior regions in depression. Anxiety was associated with increased right posterior activity, which may be related to arousal and, in anxious-depressed individuals, offset the posterior asymmetry typically seen in depression. These asymmetries have been indexed by resting EEG or inferred through the use of lateralized auditory and visual tasks (e.g., dichotic listening and chimeric faces). However, associations between regional EEG activity and neurocognitive function in depression or anxiety remain unclear. The present study used matched verbal (Word Finding) and spatial (Dot Localization) tasks to compare task-related alpha asymmetries in depressed patients grouped according to level of trait anxiety. EEG and behavioral performance were recorded from depressed patients with high anxiety (n=14) or low anxiety (n=14) and 21 age- and education-matched healthy adults during the two tasks, and alpha power was averaged within each task. As predicted, the two patient groups exhibited opposite patterns of regional hemispheric alpha asymmetry. Greater right than left central-parietal activation was seen in the high-anxiety depressed group during the spatial task, whereas greater left than right frontal-central activation was found in the low-anxiety depressed group during the verbal task. Group differences in task performance were in the expected direction but did not reach statistical significance. These results are consistent with Heller’s two-dimensional model of depression and anxiety and highlight the sensitivity of task-related EEG alpha in discriminating among subgroups of depressed patients differing in trait anxiety.
Major Depressive Disorder — NEJM
Self-ratings were obtained from the Beck Depression Inventory (BDI) and the State-Trait Anxiety Inventory-Form Y (STAI-Y). The patients were classified as high-anxiety depressed or low-anxiety depressed via the median split procedure based on level of self-rated trait anxiety. Patients with trait anxiety scores = 82 were classified as high-anxiety depressed (range = 82 – 97) and those with scores
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