Persistent decrease in alpha current density in fully remitted subjects with major depressive disorder treated with fluoxetine: A prospective electric tomography study

Resting and TMS-EEG markers of treatment response in major depressive disorder: A systematic review

Electroencephalography (EEG) is a non-invasive method to identify markers of treatment response in major depressive disorder (MDD). In this review, existing literature was assessed to determine how EEG markers change with different modalities of MDD treatments, and to synthesize the breadth of EEG markers used in conjunction with MDD treatments. PubMed and EMBASE were searched from 2000 to 2021 for studies reporting resting EEG (rEEG) and transcranial magnetic stimulation combined with EEG (TMS-EEG) measures in patients undergoing MDD treatments. The search yielded 966 articles, 204 underwent full-text screening, and 51 studies were included for a narrative synthesis of findings along with confidence in the evidence. In rEEG studies, non-linear quantitative algorithms such as theta cordance and theta current density show higher predictive value than traditional linear metrics. Although less abundant, TMS-EEG measures show promise for predictive markers of brain stimulation treatment response. Future focus on TMS-EEG measures may prove fruitful, given its ability to target cortical regions of interest related to MDD.

The long-term effects of institutional rearing, foster care intervention and disruptions in care on brain electrical activity in adolescence

Exposure to early psychosocial deprivation as a result of institutional care disrupts typical brain development. The Bucharest Early Intervention Project (BEIP) is the first longitudinal study to investigate the neurodevelopment of institutionalized infants randomized to a foster care (FCG) intervention versus care as usual (CAUG). Here, we present findings from a follow-up assessment of brain electrical activity as indexed by resting EEG at age 16 years. In addition, we examined the effects of disruption of foster care placement (e.g. the number of moves among foster care placements) on brain electrical activity. Resting-state EEG was collected from 48 CAUG, 46 FCG and 48 never institutionalized (NIG) control participants. Absolute (µV² ) and relative (proportion) power were computed from eyes closed, resting EEG data for theta, alpha and beta frequency bands. The CAUG displayed higher relative theta and lower relative alpha power compared to the FCG at 16 years of age. The FCG showed brain activity comparable to the NIG. The results further showed that disruptions following the original foster care placement had an adverse effect on brain electrical activity. Within the foster care group, there were no effects of age of placement on EEG power. Placement of children who have experienced early institutional rearing into stable foster care settings ensure long-term improvement in brain functioning.

Resting-state mapping of neural signatures of vulnerability to depression relapse

BACKGROUND

Patients with major depressive disorder (MDD) can frequently develop new depressive episodes after remission. However, the neural mechanisms underlying the increased risk for depressive relapse remain unclear. Herein, we aimed to explore whether the specific changes to regional and inter-regional spontaneous brain activities within DMN are associated with the course of episodes in pooled MDD patients.

METHODS

Resting-state functional magnetic resonance imaging was performed on patients with single-episode MDD (SEMDD, n = 30) and multiple-episode MDD (MEMDD, n = 54), and 71 age-, gender-, and educational level-matched healthy controls (HCs). We then accessed the differences in both the fractional amplitude of low-frequency fluctuations (fALFF) and functional connectivity by using the right precuneus as the seed among different groups.

RESULTS

Compared to the MEMDD and HC groups, the SEMDD group exhibited increased fALFF values in the right subgenual anterior cingulate cortex and right middle temporal gyrus. Decreased fALFF values in the right thalamus in the MEMDD group were also identified relative to the SEMDD and HC group. The peak values of fALFF in the right precuneus showed a negative correlation with the number of depressive episodes across the entire pool of MDD patients. No correlation was identified between functional connectivity using the right precuneus as the seed and the number of depressive episodes for the pooled MDD patients.

LIMITATIONS

Medication, a relatively small sample size, and hypothesis driven study.

CONCLUSIONS

Our neuroimaging results identified depression relapse-associated neural signatures and also indicated the role of reduced emotional appraisals in the thalamus. It is now possible to believe that the regional activity not inter-regional connectivity within the DMN may be involved in the pathology of depression relapse.