Functional connectivity and neuronal variability of resting state activity in bipolar disorder--reduction and decoupling in anterior cortical midline structures.

INTRODUCTION: The cortical midline structures seem to be involved in the modulation of different resting state networks, such as the default mode network (DMN) and salience network (SN). Alterations in these systems, in particular in the perigenual anterior cingulate cortex (PACC), seem to play a central role in bipolar disorder (BD). However, the exact role of the PACC, and its functional connections to other midline regions (within and outside DMN) still remains unclear in BD. METHODS: We investigated functional connectivity (FC), standard deviation (SD, as a measure of neuronal variability) and their correlation in bipolar patients (n = 40) versus healthy controls (n = 40), in the PACC and in its connections in different frequency bands (standard: 0.01-0.10 Hz; Slow-5: 0.01-0.027 Hz; Slow-4: 0.027-0.073 Hz). Finally, we studied the correlations between FC alterations and clinical-neuropsychological parameters and we explored whether subgroups of patients in different phases of the illness present different patterns of FC abnormalities. RESULTS: We found in BD decreased FC (especially in Slow-5) from the PACC to other regions located predominantly in the posterior DMN (such as the posterior cingulate cortex (PCC) and inferior temporal gyrus) and in the SN (such as the supragenual anterior cingulate cortex and ventrolateral prefrontal cortex). Second, we found in BD a decoupling between PACC-based FC and variability in the various target regions (without alteration in variability itself). Finally, in our subgroups explorative analysis, we found a decrease in FC between the PACC and supragenual ACC (in depressive phase) and between the PACC and PCC (in manic phase). CONCLUSIONS: These findings suggest that in BD the communication, that is, information transfer, between the different cortical midline regions within the cingulate gyrus does not seem to work properly. This may result in dysbalance between different resting state networks like the DMN and SN. A deficit in the anterior DMN-SN connectivity could lead to an abnormal shifting toward the DMN, while a deficit in the anterior DMN-posterior DMN connectivity could lead to an abnormal shifting toward the SN, resulting in excessive focusing on internal contents and reduced transition from idea to action or in excessive focusing on external contents and increased transition from idea to action, respectively, which could represent central dimensions of depression and mania. If confirmed, they could represent diagnostic markers in BD.

BDNF plasma levels variations in major depressed patients receiving duloxetine.

It has been frequently reported that brain-derived neurotrophic factor (BDNF) plays an important role in the pathophysiology of major depressive disorder (MDD). Objective of the study was to investigate BDNF levels variations in MDD patients during antidepressant treatment with duloxetine. 30 MDD patients and 32 healthy controls were assessed using Hamilton Depression Scale (HAM-D) and monitored for BDNF plasma levels at baseline, week 6 and week 12 of duloxetine treatment (60 mg/day) and at baseline, respectively. According to early clinical response to duloxetine (defined at week 6 by reduction >50 % of baseline HAM-D score), MDD patients were distinguished in early responders (ER) and early non-responders (ENR), who reached clinical response at week 12. Laboratory analysis showed significant lower baseline BDNF levels among patients compared to controls. During duloxetine treatment, in ENR BDNF levels increased, reaching values not significantly different compared to controls, while in ER BDNF levels remained nearly unchanged. Lower baseline BDNF levels observed in patients possibly confirm an impairment of the NEI stress-adaptation system and neuroplasticity in depression, while BDNF increase and normalization observed only in ENR might suggest differential neurobiological backgrounds in ER vs. ENR within the depressive syndrome.

Venlafaxine and risk of upper gastrointestinal bleeding in elderly depression.

In the past 10 years there has been an emphasis on the risk of upper gastrointestinal bleeding in patients taking SSRI antidepressants. Few studies have concurrently examined the possible risk of traditional antidepressants or atypical antidepressants such as venlafaxine, classified as a serotonin-norepinephrine reuptake inhibitor. In order to promote debate about possible risk of upper gastrointestinal bleeding in elderly patients taking antidepressants different from SSRIs, we report a case of venlafaxine-induced upper gastrointestinal bleeding in a 84 years old woman. Discussion about safer drugs and protective factors is provided.