Structural and functional differences in the brain of elderly with depressed MCI and non-depressed MCI and its relationship to Alzheimer\'s disease: a study by magnetic resonance

A doença de Alzheimer (DA) e a depressão tardia (DT) têm uma relação complexa e indeterminada. Nos estágios pré-demência, os pacientes com comprometimento cognitivo leve (CCL) apresentam sintomas relacionados à depressão com relativa frequência, e essa combinação aumenta a chance de progressão para DA. Trabalhos anteriores levantaram a possibilidade de que DT poderia ser um fator de risco para a DA ou o CCL deprimido (CCLD) poderia ser até mesmo um estágio prodrômico da DA. Neste trabalho, nosso objetivo foi usar a ressonância magnética para explorar as diferenças funcionais e estruturais no cérebro de pacientes com CCL com e sem depressão. Sessenta e cinco indivíduos foram divididos em quatro grupos: Cognitivamente Normal (CN), Comprometimento Cognitivo Leve Não Deprimido (CCLnD), CCLD e DA. Espessura cortical, volumes cerebrais e integridade da substância branca foram comparados entre os grupos a partir de dados estruturais de ressonância magnética. Também usamos dados de imagens de ressonância magnética funcional para avaliar as mudanças na conectividade funcional. Na comparação principal considerando os grupos CCLnD e CCLD em relação ao grupo CN: 1- Os pacientes com CCLD mostraram atrofia mais pronunciada nas estruturas do lobo temporal medial (hipocampo, amígdala e córtex entorrinal), e CCLnD apresentou maior perda geral de volume cortical. 2- O grupo CCLD apresentou assimetria significativa com maior dano estrutural no hemisfério direito. 3- O giro lingual e outras regiões mediais posteriores permaneceram estruturalmente preservado no grupo CCLD, porém, o giro lingual apresentou maior conectividade funcional com o hipocampo do que outros grupos, inclusive o grupo CN. Nossos resultados sugerem que o grupo CCLD mostra mudanças específicas no cérebro que não correspondem totalmente ao esperado para um estágio avançado de MCI nem um pródromo de AD, mas um subtipo de CCL que pode ser diferenciado usando neuroimagem.Alzheimer\'s disease (AD) and Late-life depression (LLD) have a complex and undetermined relationship. In pre-dementia stages, patients with mild cognitive impairment have depression-related symptoms with relative frequency, and this combination increases the chance of progression to AD. Previous work raised the possibility that LLD could be a risk factor for AD or depressed-MCI (DMCI) could even be a prodromal stage of AD. In this work, we aimed to use magnetic resonance imaging (MRI) to explore functional and structural differences in the brain of patients with MCI with and without depression. Sixty-five subjects were divided in four groups: Cognitively Normal (CN), Non-Depressed Mild Cognitive Impairment (nDMCI), Depressed-MCI, and AD. Cortical thickness, brain volumes and white matter integrity were compared among the groups from structural MRI data. We also used functional MRI data to assess changes in functional connectivity. In the main comparison considering nDMCI and DMCI groups related to CN: 1- DMCI patients showed more pronounced atrophy in medial temporal lobe structures (hippocampus, amygdala, and entorhinal cortex), and nDMCI showed more overall loss of cortical volume. 2- DMCI showed significant asymmetry with higher structural damage right hemisphere. 3- Lingual gyrus, and other medial posterior areas, remained structurally preserved in the DMCI group, however, the lingual gyrus showed higher functional connectivity with the hippocampus than other groups, including CN. Our findings suggest that DMCI shows specific changes in the brain that don\'t fully match the expected for an advanced stage of MCI neither a prodrome of AD, but an MCI subtype that can be differentiated using neuroimaging

Relationship between the Somatosensory Cortex Morphology, Cutaneous Allodynia, and Clinical Features of Patients with Migraine

Recent studies have demonstrated the presence of brain alterations in patients with migraine. Functional and vascular changes in the brain are related to the presence and severity of cutaneous allodynia. However, the association between brain structural changes and cutaneous allodynia has not been yet investigated in patients with migraine. Thus, the purpose of this study was to evaluate the correlation between the severity of cutaneous allodynia, migraine features, and the thickness and volume of the somatosensory cortex. Forty-five patients with migraine, with and without aura and chronic migraine, were included. Volunteers filled out the Allodynia Symptom Questionnaire (ASC-12/Brazil) and were evaluated via magnetic resonance imaging (MRI). The images were inspected by a blinded neuroradiologist and analyzed with Freesurfer software. Correlation tests and a linear regression model were used to evaluate the relationship among the outcomes. The somatosensory cortex thickness and volume were not different among migraine subgroups (p > 0.05). There was no significant correlation between the somatosensory thickness and volume with the ASC-12/Brazil, migraine frequency, intensity, migraine onset or aura frequency. The ASC-12/Brazil score variability cannot be predicted by the somatosensory cortex thickness or volume. The results show that the somatosensory cortex morphology is neither associated with cutaneous allodynia nor with migraine features among migraineurs