Translational application of neuroimaging in major depressive disorder: a review of psychoradiological studies / 医学前沿

Major depressive disorder (MDD) causes great decrements in health and quality of life with increments in healthcare costs, but the causes and pathogenesis of depression remain largely unknown, which greatly prevent its early detection and effective treatment. With the advancement of neuroimaging approaches, numerous functional and structural alterations in the brain have been detected in MDD and more recently attempts have been made to apply these findings to clinical practice. In this review, we provide an updated summary of the progress in translational application of psychoradiological findings in MDD with a specified focus on potential clinical usage. The foreseeable clinical applications for different MRI modalities were introduced according to their role in disorder classification, subtyping, and prediction. While evidence of cerebral structural and functional changes associated with MDD classification and subtyping was heterogeneous and/or sparse, the ACC and hippocampus have been consistently suggested to be important biomarkers in predicting treatment selection and treatment response. These findings underlined the potential utility of brain biomarkers for clinical practice.

Neuroimaging adolescents with depression in a middle-income country: feasibility of an fMRI protocol and preliminary results

Objective: To test the feasibility and to present preliminary results of a neuroimaging protocol to evaluate adolescent depression in a middle-income setting. Methods: We assessed psychotropic medication-free adolescents (age range 14-16 years) with a diagnosis of major depressive disorder (MDD). Participants underwent a comprehensive clinical evaluation and both structural and functional magnetic resonance imaging (fMRI). In this pilot study, a preliminary single-group analysis of resting-state fMRI (rs-fMRI) data was performed, with a focus on the default mode network (DMN), cognitive control network (CCN), and salience network (SN). Results: The sample included 29 adolescents with MDD (mean age 16.01, SD 0.78) who completed the protocol. Only two participants were excluded due to MRI quality issues (head movement), and were not included in the analyses. The scans showed significant connectivity between the medial prefrontal cortex and posterior cingulate cortex (DMN), the ACC and anterior insula (SN), and the lateral prefrontal cortex and dorsal parietal cortex (CCN). Conclusion: We demonstrated the feasibility of implementing a complex neuroimaging protocol in a middle-income country. Further, our preliminary rs-fMRI data revealed patterns of resting-state connectivity consistent with prior research performed in adolescents from high-income countries.

Global hippocampal atrophy in major depressive disorder: a meta-analysis of magnetic resonance imaging studies / Atrofia global do hipocampo no transtorno depressivo maior: uma metanálise de estudos com ressonância magnética

Abstract Introduction: Major depressive disorder (MDD), an incapacitating mental disorder, is characterized by episodes of at least 2 weeks of apparent changes in mood, cognition, and neurovegetative functions. Many neuroimaging studies using magnetic resonance imaging (MRI) have examined morphometric changes in patients with MDD, but the results are not conclusive. This study aims to review the literature and perform a meta-analysis on hippocampal volume (HcV) in patients with MDD. Methods: Studies on HcV in patients with MDD diagnosis were identified from major databases (MEDLINE, EMBASE, The Cochrane Library, Scopus, PsycINFO, and SciELO) using the search terms depression, major depressive disorder, MDD, unipolar, magnetic resonance imaging, MRI, and hippocampus. Results: A meta-analysis of 29 studies fulfilling specific criteria was performed. The sample included 1327 patients and 1004 healthy participants. The studies were highly heterogeneous with respect to age, sex, age of onset, and average illness duration. However, the pooled effect size of depression was significant in both hippocampi. MDD was associated with right (-0.43; 95% confidence interval [95%CI] −0.66 to −0.21) and left (-0.40; 95%CI −0.66 to −0.15) hippocampal atrophy. Conclusions: MDD seems to be associated with global HcV atrophy. Larger longitudinal follow-up studies designed to analyze the influence of sociodemographic variables on this relationship are required to yield better evidence about this topic.

Resumo Introdução: O transtorno depressivo maior (TDM) é uma doença mental incapacitante caracterizada por episódios de pelo menos 2 semanas de mudanças claras no afeto, cognição e funções neurovegetativas. Vários estudos de neuroimagem, realizados através de imagem de ressonância magnética (IRM), examinaram mudanças morfométricas em pacientes com TDM, com resultados não conclusivos. Este estudo tem como objetivo revisar a literatura e realizar uma metanálise sobre o volume do hipocampo (VHc) em pacientes com TDM. Métodos: Estudos de VHc em pacientes com TDM foram identificados a partir dos principais bancos de dados (MEDLINE, EMBASE, The Cochrane Library, Scopus, PsycINFO e SciELO) usando os seguintes termos: depression, major depressive disorder, MDD, unipolar, magnetic resonance imaging, MRI e hippocampus. Resultados: Foi realizada uma metanálise de 29 estudos que preencheram os critérios específicos. A amostra foi composta por 1327 pacientes e 1004 indivíduos saudáveis. Os estudos foram altamente heterogêneos em relação a idade, gênero, idade do primeiro episódio e duração média da doença, mas o efeito combinado da depressão foi significativo em ambos os hipocampos. O TDM foi associado à atrofia do hipocampo à direita [-0,43; intervalo de confiança de 95% (IC95%) −0,66 a −0,21] e à esquerda (-0,40; IC95% −0,66 a −0,15). Conclusões: O TDM parece estar associado à atrofia global do VHc. Estudos longitudinais com maior tempo de seguimento, projetados para analisar a influência dos fatores sociodemográficos nessa relação, são necessários para obter evidências mais robustas.