Depression with Mixed Features (for DSM-5): Distinguishing Indicators Imaginary Coherence EEG Rest

Background: The neuronal correlates of depression with mixed traits (according to DSM-5) at rest have not been studied. Objective: to determine the indicators of imaginary coherence of EEG-rest, which distinguish patients with depression with mixed features (according to DSM-5) from patients with depression without mixed features and healthy subjects, and also to trace the dependence of the identified neurophysiological characteristics on the diagnostic belonging of the symptom complex to bipolar II type or recurrent depressive disorder. Patients and methods: on a background free from drug therapy, 80 patients with depression with mixed features (XD; n = 40 — with bipolar II disorder (XB) and n = 40 — with recurrent depressive disorder (XR)), 80 patients with depression without mixed traits (TD; n = 40 — for bipolar II type (TB) and n = 40 — for recurrent depressive disorder (TR), as well as 80 healthy subjects (N). The study groups were matched by sex and age. The study used clinical-psychopathological, psychometric, neurophysiological and statistical research methods. According to the Kruskal–Wallis criterion for independent samples the parameters of imaginary coherence (modulo) of standard frequency ranges (delta (δ) — 0.5–4 Hz, theta (θ) — 4–8 Hz, alpha (α) — 8–13 Hz, beta-1 (β1) — 13–20 Hz, beta-2 (β2) — 20–30 Hz, gamma (γ) — 30–45 Hz) between pairs of 14 cutaneous standard EEG derivations (according to the “10–20” system) in three (XD, TD and N), and then in five (XB, XR, TB, TR and N) comparison groups. Post-hoc analysis was performed using the U-test. The significance level was adjusted according to the Bonferroni correction. Results: three indicators were identified: α-ICoh(C3–P4), β1-ICoh(C3–P3) and β2-ICoh(F3–C4). For all three parameters, the H-test values for the “Group” factor (n = 3 and n = 5) were highly significant. In this case, α-ICoh(C3– P4) — XD = TD, XD < N, TD < N; β1-ICoh(C3–P3) — XD < TD, XD < N; TD < N; β2-ICoh(F3–C4) — XD > TD; XD > N, TD > N. The groups of patients with XD within the framework of recurrent depressive and bipolar II disorders significantly differed in terms of β1- ICoh(C3–P3) — XR > XB. At the level of statistical trends, in type II bipolar disorder — XB > TB according to α-ICoh(C3–P4), and in recurrent depressive disorder — XR > TR according to β2-ICoh(F3–C4). Conclusion. Thus, depression with mixed features can be considered in terms of dysfunctional interactions of the left frontal, bilateral central and parietal cortical zones, depending on the diagnostic affiliation of the depressive symptom complex and reflecting violations of automatic and voluntary regulation of affect, cognitive and behavioral changes.

Plasma BDNF and Cytokines Correlated with Protein Biomarkers for Bipolar II Disorder

We have previously identified five candidate proteins (matrix metallopeptidase 9 (MMP9), phenylalanyl-TRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin Type 9 (PCSK9)) as potential biomarkers for bipolar II disorder (BD-II). These candidate proteins have been associated with neuroprotective factors (BDNF) and inflammatory factors (cytokines, C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α)). However, the correlations between these proteins with plasma BDNF and inflammatory factors remain unknown. We recruited a total of 185 patients with BD-II and 186 healthy controls. Plasma levels of candidate proteins, BDNF, cytokines (TNF-α, CRP, and interleukin-8 (IL-8)) were assessed from each participant. The correlations between levels of candidate proteins, BDNF, and cytokines were analyzed. In the BD-II group, we found that the level of FARSB was positively correlated with the BDNF level (r = 0.397, p < 0.001) and IL-8 (r = 0.320, p < 0.001). The CA-1 level positively correlated with IL-8 (r = 0.318, p < 0.001). In the control group, we found that the FARSB level positively correlated with the BDNF level (r = 0.648, p < 0.001). The CA-1 level positively correlated with TNF-α (r = 0.231, p = 0.002), while the MMP-9 level positively correlated with the CRP level (r = 0.227, p = 0.002). Our results may help in clarifying the underlying mechanism of these candidate proteins for BD-II.

Differences in verbal and spatial working memory in patients with bipolar II and unipolar depression: an MSI study

Background Depressive symptoms could be similarly expressed in bipolar and unipolar disorder. However, changes in cognition and brain networks might be quite distinct. We aimed to find out the difference in the neural mechanism of impaired working memory in patients with bipolar and unipolar disorder. Method According to diagnostic criteria of bipolar II disorder of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and assessments, 13 bipolar II depression (BP II), 8 unipolar depression (UD) patients and 15 healthy controls (HC) were recruited in the study. We used 2-back tasks and magnetic source imaging (MSI) to test working memory functions and get the brain reactions of the participants. Results Compared with HC, only spatial working memory tasks accuracy was significantly worse in both UD and BP II (p = 0.001). Pearson correlation showed that the stronger the FCs’ strength of MFG-IPL and IPL-preSMA, the higher accuracy of SWM task within left FPN in patients with UD (r = 0.860, p = 0.006; r = 0.752, p = 0.031). However, the FC strength of IFG-IPL was negatively correlated with the accuracy of SWM task within left FPN in patients with BP II (r = − 0.591, p = 0.033). Conclusions Our study showed that the spatial working memory of patients with whether UD or BP II was impaired. The patterns of FCs within these two groups of patients were different when performing working memory tasks.