Correlation of Cognitive Reappraisal and the Microstructural Properties of the Forceps Minor: A Deductive Exploratory Diffusion Tensor Imaging Study.

Cognitive reappraisal (CR) is a mechanism for emotion regulation, and the prefrontal cortex (PFC) plays a central role in the regulation of emotions. We tested the hypothesis of an association between CR function and microstructural properties of forceps minor (a commissural bundle within the PFC) in healthy subjects (HS). We analyzed a population of 65 young HS of a public dataset. The diffusion tensor imaging (DTI) sequence of every subject was analyzed to extract the derived shape (diameter and volume) and DTI metrics in terms of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) of the forceps minor. The CR subscale of the German version of the Emotion Regulation Questionnaire (ERQ) was used for CR assessment. The Shapiro-Wilk test was applied to test the assumption of normality in all these parameters, adopting a statistical threshold at p < 0.05. Whenever appropriate a non-parametric two-tailed partial correlation analysis was applied to test for correlations between the CR ERQ score and the derived shape and DTI metrics, including age and sex as confounders, adopting a statistical threshold at p < 0.05. The non-parametric two-tailed partial correlation analysis revealed a mildly significant correlation with FA (ρ = 0.303; p = 0.016), a weakly significant negative correlation with MD (ρ = - 0.269; p = 0.033), and a mildly significant negative correlation with RD (ρ = - 0.305; p = 0.015). These findings suggest a correlation between DTI microstructural properties of forceps minor and CR.

The mid-term effects of carotid endarterectomy on cognition and regional neural activity analyzed with the amplitude of low frequency fluctuations technique.

PURPOSE: The study aims to evaluate the mid-term effects of carotid endarterectomy (CEA) on cognition and resting-state functional magnetic resonance imaging (rs-fMRI) using the Amplitude of Low Frequency Fluctuations (ALFF) technique. METHODS: In this observational study, patients eligible for CEA were prospectively included. On the same day, within 1 week of the CEA procedure performed and 12 months after the CEA procedure, all patients underwent (i) an MRI examination for rs-fMRI analysis and (ii) a cognitive evaluation using the Italian version of the Mini-Mental State Examination (MMSE) corrected for age and schooling. Pre-CEA and post-CEA MMSE scores were evaluated using paired sample t-tests, adopting a p-value < 0.05 as statistical threshold. The ALFF technique was used for analyzing the differences between pre-CEA and post-CEA rs-fMRI scans in terms of regional neural activation. This was accomplished by applying non-parametric statistics based on randomization/permutation for cluster-level inferences, adopting a cluster-mass p-value corrected for false discovery < 0.05 for cluster threshold, and a p-uncorrected < 0.01 for the voxel threshold. RESULTS: Twenty asymptomatic patients were enrolled. The mean MMSE score resulted improved following CEA procedure (p-value = 0.001). The ALFF analysis identified a single cluster of 6260 voxels of increased regional neural activity following CEA, and no cluster of reduced activity. The majority of voxels covered the right precentral gyrus, the right middle frontal gyrus, and the anterior division of the cingulate gyrus. CONCLUSION: Mid-term cognitive improvements observed after CEA are associated to increased regional neural activity of several cerebral regions.

The association between white matter hyperintensities, cognition and regional neural activity in healthy subjects.

White matter hyperintensities (WMH) are common findings that can be found in physiological ageing. Several studies suggest that the disruption of white matter tracts included in WMH could induce abnormal functioning of the respective linked cortical structures, with consequent repercussion on the cerebral functions, included the cognitive sphere. In this cross-sectional research, we analysed the effects of the total WMH burden (tWMHb) on resting-state functional magnetic resonance imaging (rs-fMRI) and cognition. Functional and structural MR data, as well as the scores of the trail making test subtests A (TMT-A) and B (TMT-B) of 75 healthy patients, were extracted from the public available Leipzig Study for Mind-Body-Emotion Interactions dataset. tWMHb was extracted from structural data. Spearman's correlation analyses were made for investigating correlations between WMHb and the scores of the cognitive tests. The fractional amplitude of low-frequency fluctuations (fALFF) method was applied for analysing the rs-fMRI data, adopting a multiple regression model for studying the effects of tWMHb on brain activity. Three different subanalyses were conducted using different statistical methods. We observed statistically significant correlations between WMHb and the scores of the cognitive tests. The fALFF analysis revealed that tWMHb is associated with the reduction of regional neural activity of several brain areas (in particular the prefrontal cortex, precuneus and cerebellar crus I/II). We conclude that our findings clarify better the relationships between WMH and cognitive impairment, evidencing that tWMHb is associated with impairments of the neurocognitive function in healthy subjects by inducing a diffuse reduction of the neural activity.

Capgras syndrome in Parkinson's disease: two new cases and literature review.

The Capgras syndrome (CS) is a rare psychiatric disorder. CS is classified as a delusional misidentification syndrome. Initially, CS was described in paranoid schizophrenia and schizoaffective disorders. CS has also been reported in neurodegenerative diseases such as Alzheimer's disease and Lewy body dementia. To date, there are very few descriptions of the occurrence of CS in idiopathic Parkinson's disease (PD), with or without dementia. Considering the recent observation of two new cases in PD patients, a systematic overview of the literature published between 1976 and 2016 reporting CS in PD was conducted. The purpose of this article is to examine the phenomenon in people with PD with and without dementia, the psychopathologic context in which it happened, the role played by the dopaminergic medications and to define useful therapeutic strategies. Our CS cases occurred in two elderly patients with advanced PD and cognitive impairment, respectively, after an acute stressor event and after an increase of the total daily dose of levodopa. In light of our observations and the cases reported in the literature, we argue that CS is an acute or subacute psychotic disorder occurring mostly in PD with dementia. Besides, the increase in brain dopamine levels induced by acute stressful events and/or dopamine-enhancing medications should be considered as a possible causal mechanism of CS in patients with advanced stages of PD and cognitive decline.

Impact of corpus callosum integrity on functional interhemispheric connectivity and cognition in healthy subjects.

To examine the corpus callosum's (CC) integrity in terms of fractional anisotropy (FA) and how it affects resting-state hemispheric connectivity (rs-IHC) and cognitive function in healthy individuals. Sixty-eight healthy individuals were recruited for the study. The global FA (gFA) and FA values of each CC tract (forceps minor, body, tapetum, and forceps major) were evaluated using diffusion-weighted imaging (DWI) sequences. The homotopic functional connectivity technique was used to quantify the effects of FA in the CC tracts on bilateral functional connectivity, including the confounding effect of gFA. Brain regions with higher or lower rs-IHC were identified using the threshold-free cluster enhancement family-wise error-corrected p-value of 0.05. The null hypothesis was rejected if the p-value was ≤ 0.05 for the nonparametric partial correlation technique. Several clusters of increased rs-IHC were identified in relation to the FA of individual CC tracts, each with a unique topographic distribution and extension. Only forceps minor FA values correlated with cognitive scores. The integrity of CC influences rs-IHC differently in healthy subjects. Specifically, forceps minor anisotropy impacts rs-IHC and cognition more than other CC tracts do.

The restoring of interhemispheric brain connectivity following carotid endarterectomy: an exploratory observational study.

This study aimed to evaluate the differences of brain connectivity between healthy subjects (HS) and patients with extracranial internal carotid artery (eICA) stenosis before and after carotid endarterectomy (CEA). An exploratory prospective study was designed. The study population consisted of a patient group (PG) of 20 patients with eICA stenosis eligible for CEA, and a control group (CG) of 20 HS, matched for age and sex. The subjects of the PG group underwent Magnetic Resonance Imaging (MRI) for resting-state functional connectivity MRI (rs-fc MRI) analysis within one week from the CEA (pre-CEA) and 12 months following CEA (post-CEA). The CG underwent a single MRI with the same protocol utilized for the PG. Three region-of-interest to region-of-interest (ROI-to-ROI) rs-fc MRI analyses were conducted: analysis 1 to compare pre-CEA PG and CG; analysis 2 to compare pre-CEA PG and post-CEA PG; analysis 3 to compare post-CEA PG and CG. The Functional Network Connectivity multivariate parametric technique was used for statistical analysis, adopting a p-uncorrected (p-unc) < 0.05 as connection threshold, and a cluster level False Discovery Rate corrected p (p-FDR) < 0.05 as cluster threshold. The clusters were defined by using a data-driven hierarchical clustering procedure. Analysis 1 revealed two clusters of reduced interhemispheric connectivity of pre-CEA PG when compared to CG. Analysis 2 and 3 showed no statistically significant differences. Our exploratory analysis suggests that patients with eICA stenosis have reduced interhemispheric connectivity when compared to a matched control group, and this difference was not evident anymore following endarterectomy.

Mid-term effects of carotid endarterectomy on cognition and white matter status evaluated by whole brain diffusion tensor imaging metrics: A preliminary analysis.

PURPOSE: To analyze the mid-term (12 months) effects of carotid endarterectomy (CEA) on cognition and on the microstructural properties of the whole brain white matter in terms of derived diffusion Tensor imaging (DTI) metrics. METHODS: We analyzed a population of 19 asymptomatic patients with extra-cranial internal carotid artery stenosis (eICA) eligible for CEA. All patients underwent cognitive evaluation with the Italian version of the Mini-Mental State Examination corrected for age and schooling, and with a Magnetic Resonance Imaging (MRI) investigation on a 1.5 Tesla MRI scanner, that included a 34-directions Diffusion Weighted Imaging (DWI) sequence for DTI metrics analysis. The global fractional anisotropy (gFA), global mean diffusivity (gMD), global radial diffusivity (gRD) and global axial diffusivity (gAD) were calculated for each patient. Both the cognitive and the imaging evaluation were performed at baseline (PRE-CEA) and 12 months after CEA (POST-CEA). Two-tailed Paerson's correlation test and paired samples t-test were used for evaluating the correlation between PRE-CEA and POST-CEA values, adopting a p-value of <0.05 as statistically significant. RESULTS: A statistically significant increase of the MMSE scores (p < 0.0001), as well as for gFA (p < 0.0001), and a statistically significant reduction of gMD (p = 0.027) and gRD (p = 0.0005) was observed 12 months following uncomplicated CEA. CONCLUSIONS: These findings suggest that CEA is associated with a general improvement of the WM microstructure of the whole brain.

Global Fractional Anisotropy: Effect on Resting-state Neural Activity and Brain Networking in Healthy Participants.

The global fractional anisotropy (gFA) is a structural marker of white matter myelination and integrity. Previous studies already evidenced that aging-related reduced integrity of specific white matter tracts is associated with decreased functional connectivity in several hubs. However, the correlations between gFA and functional brain connectivity remain unknown. In this cross-sectional study, we analyzed structural and functional MR datasets of 79 healthy participants from the Leipzig Study for Mind-Body-Emotion Interactions. DTI model-based method was used to quantify gFA values. We tested associations between gFA, age, and gender. The fractional amplitude of low-frequency fluctuations (fALFF) and ROI-to-ROI connectivity were analyzed in a regression model for evaluating the effects of gFA on brain activity and networking, respectively. A negative correlation was found between gFA and age (ρ = -0.343; p = 0.002). No statistically significant correlation as found between gFA and gender (p = 0.229). Higher values of gFA were associated with increased brain regional activity, including areas of the default mode network. There was a higher degree of correlation between some regions, particularly those that conform to the limbic system. Our study demonstrates that gFA influences regional neural activity and brain networking on resting, particularly the limbic system.

Extracranial Carotid Artery Stenosis: The Effects on Brain and Cognition with a Focus on Resting-State Functional Connectivity.

Extracranial carotid artery stenosis (ECAS) due to the presence of atherosclerotic plaque is a well-known risk factor for stroke. Several structural imaging studies have investigated the effect of ECAS on the brain, focusing on structural damage (in particular cerebral small vessel disease) and on the rearrangement of the cerebral circulation. For example, it is known from the literature an association between carotid stenosis and cerebral small vessel disease, and it is also noted that a series of compensatory mechanisms are activated by the cerebrovascular system in order to overcome the cerebral hypoperfusion that is induced by the ECAS. Several neurocognitive studies have also investigated the association of ECAS with cognitive deficits. While the evidence tends to favor a direct association between ECAS and cognition, the actual relationship remains controversial. In the last decade, various resting-state functional connectivity (rs-fc) magnetic resonance (MR) studies have tried to elucidate the "in vivo" mechanisms underlying the cognitive impairment observed in these patients. Although these studies have been performed on small cohorts of patients without standardized protocols, it is plausible that in the future, such studies will help find early stage markers of cognitive impairment. This could permit an extension of indications for revascularization for the treatment of cognitive impairment in selected patients. The aim of this narrative review is to discuss the current knowledge on the effects of ECAS on brain and cognition by analyzing the main evidence from animal and clinical studies, with a special focus on rs-fc MR studies.