Revisiting Hemispheric Asymmetry in Mood Regulation: Implications for rTMS for Major Depressive Disorder

Hemispheric differences in emotional processing have been observed for over half a century, leading to multiple theories classifying differing roles for the right and left hemisphere in emotional processing. Conventional acceptance of these theories has had lasting clinical implications for the treatment of mood disorders. The theory that the left hemisphere is broadly associated with positively valenced emotions, while the right hemisphere is broadly associated with negatively valenced emotions, drove the initial application of repetitive transcranial magnetic stimulation (rTMS) for the treatment of major depressive disorder (MDD). Subsequent rTMS research has led to improved response rates while adhering to the same initial paradigm of administering excitatory rTMS to the left prefrontal cortex (PFC) and inhibitory rTMS to the right PFC. However, accumulating evidence points to greater similarities in emotional regulation between the hemispheres than previously theorized, with potential implications for how rTMS for MDD may be delivered and optimized in the near future. This review will catalog the range of measurement modalities that have been used to explore and describe hemispheric differences, and highlight evidence that updates and advances knowledge of TMS targeting and parameter selection. Future directions for research are proposed that may advance precision medicine and improve efficacy of TMS for MDD.

Gender differences in positive screen for depression and diagnosis among older adults in Chile

Background Different factors are associated with late life depression and diagnosis, including gender. It has also been reported that depression among older people is underdiagnosed. As a result, the mental health needs of this group are insufficiently met. The aim of this study was to explore gender differences in the factors associated with positive screens for depression and self-reported diagnosis among older adults in Chile. Methods Data from 3786 older adults who participated in the Social Protection Survey in 2016 were analysed. PHQ-9 was used to identify screen-positive cases. Self-reported diagnosis of depression was used to determine the proportion of people with a screen-positive result who had received a diagnosis of depression. Logistic regression models were used to determine sociodemographic and health factors associated with depression and underdiagnosis in older men and women. Results The prevalence of a screen-positive result was 20.91% (5.83% major depressive disorder) among men, and 36.38% (12.43% major depressive disorder) among women. 18.77% of men and 34.11% of women with a positive depression screening had received a diagnosis. More educated men were more likely to receive a diagnosis. Older age was associated with a lower probability of diagnosis among older women. Conclusions Our results suggest that depressive disorders are undiagnosed in a high proportion of older adults in Chile. Gender is a relevant factor in the underdiagnosis of depression in this group. Further research is needed to understand the factors involved in these gaps, to improve detection and provide timely support and treatment.

Family Conflict Associated With Intrinsic Hippocampal-OFC Connectivity in Adolescent Depressive Disorder

BackgroundFamily environment and life events have long been suggested to be associated with adolescent depression. The hippocampus plays a crucial role in the neural mechanism of major depressive disorder (MDD) through memory during stressful events. However, few studies have explored the exact neural mechanisms underlying these associations. Thus, the current study aimed to explore alterations in hippocampal functional connectivity (FC) in adolescent MDD based on resting-state functional magnetic resonance imaging and further investigate the relationship between hippocampal FC, environmental factors, and clinical symptom severity.MethodsHippocampal FC was calculated using the seed-based approach with the bilateral hippocampus as the seed for 111 adolescents with and without MDD; comparisons were made between participants with MDD and controls. We applied the Chinese version of the Family Environment Scale (FES-CV) and Adolescents Self-Rating Life Events Checklist (ASLEC) to evaluate family environment and life stress. Their relationship with hippocampal FC alterations was also investigated.ResultsWe found that compared to controls, adolescents with MDD showed decreased connectivity between the left hippocampus and bilateral orbital frontal cortex (OFC) and right inferior temporal gyrus. In addition, the hippocampal-OFC connectivity was negatively correlated with conflict scores of the FES-CV in the MDD group and mediated the association between family conflict and depressive and anxiety symptoms.ConclusionOur findings are novel in the field and demonstrate how family conflict contributes to MDD symptomatology through hippocampal-OFC connectivity; these findings may provide potential targets for personalized treatment strategies.