Discovery and replication of cerebral blood flow differences in major depressive disorder.

Major depressive disorder (MDD) is a serious, heterogeneous disorder accompanied by brain-related changes, many of which are still to be discovered or refined. Arterial spin labeling (ASL) is a neuroimaging technique used to measure cerebral blood flow (CBF; perfusion) to understand brain function and detect differences among groups. CBF differences have been detected in MDD, and may reveal biosignatures of disease-state. The current work aimed to discover and replicate differences in CBF between MDD participants and healthy controls (HC) as part of the EMBARC study. Participants underwent neuroimaging at baseline, prior to starting study medication, to investigate biosignatures in MDD. Relative CBF (rCBF) was calculated and compared between 106 MDD and 36 HC EMBARC participants (whole-brain Discovery); and 58 MDD EMBARC participants and 58 HC from the DLBS study (region-of-interest Replication). Both analyses revealed reduced rCBF in the right parahippocampus, thalamus, fusiform and middle temporal gyri, as well as the left and right insula, for those with MDD relative to HC. Both samples also revealed increased rCBF in MDD relative to HC in both the left and right inferior parietal lobule, including the supramarginal and angular gyri. Cingulate and prefrontal regions did not fully replicate. Lastly, significant associations were detected between rCBF in replicated regions and clinical measures of MDD chronicity. These results (1) provide reliable evidence for ASL in detecting differences in perfusion for multiple brain regions thought to be important in MDD, and (2) highlight the potential role of using perfusion as a biosignature of MDD.

Do baseline sub-threshold hypomanic symptoms affect acute-phase antidepressant outcome in outpatients with major depressive disorder? Preliminary findings from the randomized CO-MED trial.

Sub-threshold hypomanic symptoms are common in major depressive disorder. This study evaluated the prevalence, the clinical and sociodemographic correlates, and the overall and differential effects of the presence/absence of sub-threshold hypomanic symptoms at baseline on acute-phase treatment outcomes with bupropion-plus-escitalopram combination, escitalopram monotherapy, and venlafaxine-plus-mirtazapine combination. Combining medications to enhance depression outcomes (CO-MED) trial participants (n = 665) were designated as sub-threshold hypomanic symptoms present (Altman Self-Rating Mania Scale score (ASRM) ≥ 1) or absent (ASRM = 0) and compared on clinical and sociodemographic features and remission rates. Participants with sub-threshold hypomanic symptoms (n = 335/665, 50.4%) were more likely to be black and non-Hispanic, have comorbid medical and psychiatric disorders, experience longer index episodes, and report lower depression severity and psychosocial impairment. Intent-to-treat remission rates were lower overall (absent = 42.7%, present = 34.0%, p = 0.02), with escitalopram monotherapy (absent = 45.8%, present = 31.6%, p = 0.03), and with venlafaxine-XR-plus-mirtazapine combination (absent = 44.4%, present = 30.1%, p = 0.03) but not with bupropion-plus-escitalopram combination (absent = 37.7%, present = 40.0%, p = 0.73). Participants without sub-threshold hypomanic symptoms were more likely to remit than those with such symptoms overall [odds ratio (OR) = 1.49], with escitalopram monotherapy (OR = 1.71), and with venlafaxine-plus-mirtazapine combination (OR = 1.97) but not with bupropion-plus-escitalopram combination (OR = 0.96), even after controlling for baseline depression severity, psychosocial impairment, and number of comorbid psychiatric disorders. Sub-threshold hypomanic symptoms (found in about 50% of patients in this report) were associated with lower remission rates with escitalopram monotherapy and with venlafaxine-plus-mirtazapine combination but not with the bupropion-plus-escitalopram combination.

Characterizing anxiety subtypes and the relationship to behavioral phenotyping in major depression: Results from the EMBARC study.

The current study aimed to characterize the multifaceted nature of anxiety in patients with major depression by evaluating distinct anxiety factors. We then related these derived anxiety factors to performance on a Flanker Task of cognitive control, in order to further validate these factors. Data were collected from 195 patients with nonpsychotic chronic or recurrent major depression or dysthymic disorder. At baseline, participants completed self-report measures of anxiety, depression, and other related symptoms (mania, suicidality) and clinicians administered a structured diagnostic interview and the Hamilton Rating Scale for Depression, including anxiety/somatization items. Four discrete factors (State Anxiety, Panic, Neuroticism/Worry, and Restlessness/Agitation) emerged, with high degrees of internal consistency. Discriminant and convergent validity analyses also yielded findings in the expected direction. Furthermore, the neuroticism/worry factor was associated with Flanker Task interference, such that individuals higher on neuroticism/worry responded more incorrectly (yet faster) to incongruent vs. congruent trials whereas individuals higher on the fear/panic factor responded more slowly, with no accuracy effect, to the Flanker Task stimuli. These results parse anxiety into four distinct factors that encompass physiological, psychological, and cognitive components of anxiety. While state anxiety, panic and neuroticism/worry are related to existing measures of anxiety, the Restlessness/Agitation factor appears to be a unique measure of general anxious arousal. Furthermore, two factors were independently validated through the Flanker Task. These results suggest that these anxiety domains have distinct behavioral profiles and could have differential responses to distinct treatments.