Background Cognitive remediation therapy positively affects cognition and daily functioning in patients with schizophrenia. However, studies on the underlying neurobiological mechanisms of this ...treatment are scarce. The aim of the current study was to investigate functional and structural connectivity brain changes in schizophrenia patients after cognitive remediation therapy using a whole-brain approach that combined functional magnetic resonance imaging and diffusion tensor imaging. Methods A randomized controlled trial with 30 schizophrenia outpatients and 15 healthy volunteers. A strategy-learning-based treatment was used as a cognitive remediation therapy. A social skills training that provides useful information about illness management was used as an active control. We investigated changes in the pattern of functional connectivity assessed during an n-back task by tensorial independent component analysis as implemented in the multivariate exploratory linear decomposition into independent components and in the fractional anisotropy index of white matter integrity using tract-based spatial statistics. Results Brain networks activation pattern significantly changed in patients exposed to the cognitive treatment in the sense of normalizing toward the patterns observed in healthy control subjects. Additionally, in white matter, they showed an increase in fractional anisotropy index in the anterior part of the genu of the corpus callosum. Cognitive improvement, functional, and also structural changes showed statistically significant correlations. Conclusions Improvement in brain functioning detected after cognitive remediation therapy in schizophrenia patients might be based on an increase of the interhemispheric information transfer between the bilateral prefrontal cortexes via the corpus callosum.
Recent studies associated rapid eye movement sleep behavior disorder (RBD) in Parkinson's disease (PD) with severe cognitive impairment and brain atrophy. However, whole-brain functional connectivity ...has never been explored in this group of PD patients. In this study, whole-brain network-based statistics and graph-theoretical approaches were used to characterize resting-state interregional functional connectivity in PD with probable RBD (PD-pRBD) and its relationship with cognition. Our sample consisted of 30 healthy controls, 32 PD without probable RBD (PD-non pRBD), and 27 PD-pRBD. The PD-pRBD group showed reduced functional connectivity compared with controls mainly involving cingulate areas with temporal, frontal, insular, and thalamic regions (p < 0.001). Also, the PD-pRBD group showed reduced functional connectivity between right ventral posterior cingulate and left medial precuneus compared with PD-non pRBD (p < 0.05). We found increased normalized characteristic path length in PD-pRBD compared with PD-non pRBD. In the PD-pRBD group, mean connectivity strength from reduced connections correlated with visuoperceptual task and normalized characteristic path length correlated with processing speed and verbal memory tasks. This work demonstrates the existence of disrupted functional connectivity in PD-pRBD, together with abnormal network integrity, that supports its consideration as a severe PD subtype.
Objective The objective of the study was to evaluate cortical development parameters by magnetic resonance imaging (MRI) in late-onset intrauterine growth–restricted (IUGR) fetuses and normally grown ...fetuses. Study Design A total of 52 IUGR and 50 control fetuses were imaged using a 3T MRI scanner at 37 weeks of gestational age. T2 half-Fourier acquisition single-shot turbo spin-echo anatomical acquisitions were obtained in 3 planes. Cortical sulcation (fissures depth corrected by biparietal diameter), brain volumetry, and asymmetry indices were assessed by means of manual delineation and compared between cases and controls. Results Late-onset IUGR fetuses had significantly deeper measurements in the left insula (late-onset IUGR: 0.293 vs control: 0.267; P = .02) and right insula (0.379 vs 0.318; P < .01) and the left cingulate fissure (0.096 vs 0.087; P = .03) and significantly lower intracranial (441.25 cm3 vs 515.82 cm3 ; P < .01), brain (276.47 cm3 vs 312.07 cm3 ; P < .01), and left opercular volumes (2.52 cm3 vs 3.02 cm3 ; P < .01). IUGR fetuses showed significantly higher right insular asymmetry indices. Conclusion Late-onset IUGR fetuses had a different pattern of cortical development assessed by MRI, supporting the existence of in utero brain reorganization. Cortical development could be useful to define fetal brain imaging-phenotypes characteristic of IUGR.
The default-mode network (DMN) is affected by advancing age, where particularly long-range connectivity has been consistently reported to be reduced as compared to young individuals. We examined ...whether there were any differences in the effects of intermittent theta-burst stimulation (iTBS) in DMN connectivity between younger and older adults, its associations with cognition and brain integrity, as well as with long-term cognitive status. Twenty-four younger and 27 cognitively normal older adults were randomly assigned to receive real or sham iTBS over the left inferior parietal lobule between two resting-state functional magnetic resonance imaging (rs-fMRI) acquisitions. Three years later, those older adults who had received real iTBS underwent a cognitive follow-up assessment. Among the younger adults, functional connectivity increased following iTBS in distal DMN areas from the stimulation site. In contrast, older adults exhibited increases in connectivity following iTBS in proximal DMN regions. Moreover, older adults with functional responses to iTBS resembling those of the younger participants exhibited greater brain integrity and higher cognitive performance at baseline and at the 3-year follow-up, along with less cognitive decline. Finally, we observed that ‘young-like’ functional responses to iTBS were also related to the educational background attained amongst older adults. The present study reveals that functional responses of the DMN to iTBS are modulated by age. Furthermore, combining iTBS and rs-fMRI in older adults may allow characterizing distinctive cognitive profiles in aging and its progression, probably reflecting network plasticity systems that may entail a neurobiological substrate of cognitive reserve.
•iTBS exerts distinctive effects in DMN connectivity in younger and older adults.•iTBS-fMRI metrics can identify meaningful associations between brain networks functioning and cognition in aging.•The iTBS-fMRI approach can allow to distinguish different cognitive trajectories in aging.•iTBS-fMRI measures could reflect a network plasticity mechanism of cognitive reserve.
Abstract We used resting-functional magnetic resonance imaging data from 98 healthy older adults to analyze how local and global measures of functional brain connectivity are affected by age, and ...whether they are related to differences in memory performance. Whole-brain networks were created individually by parcellating the brain into 90 cerebral regions and obtaining pairwise connectivity. First, we studied age-associations in interregional connectivity and their relationship with the length of the connections. Aging was associated with less connectivity in the long-range connections of fronto-parietal and fronto-occipital systems and with higher connectivity of the short-range connections within frontal, parietal, and occipital lobes. We also used the graph theory to measure functional integration and segregation. The pattern of the overall age-related correlations presented positive correlations of average minimum path length (r = 0.380, p = 0.008) and of global clustering coefficients (r = 0.454, p < 0.001), leading to less integrated and more segregated global networks. Main correlations in clustering coefficients were located in the frontal and parietal lobes. Higher clustering coefficients of some areas were related to lower performance in verbal and visual memory functions. In conclusion, we found that older participants showed lower connectivity of long-range connections together with higher functional segregation of these same connections, which appeared to indicate a more local clustering of information processing. Higher local clustering in older participants was negatively related to memory performance.
Abstract Objectives To describe brain magnetic resonance imaging (MRI) abnormalities in newly diagnosed neuropsychiatric lupus (NPSLE). To correlate them with clinical and laboratory data. Methods ...This retrospective cross-sectional study included patients presenting NPSLE undergoing brain MRI within 6 months after onset between 2003 and 2012. Clinical and laboratory data were recorded. MRI findings were defined as inflammatory-like, large-vessel disease (LVD), and small-vessel disease (SVD); SVD was classified as white-matter hyperintensities (WMH), recent small subcortical infarcts, lacunes, microbleeds, and brain atrophy. Results We included 108 patients (mean 40.6 ± 14.2 years; range 14–77), 91.7% women. The most frequent syndromes were headache (28.5%), cerebrovascular disease (15.5%), seizure (15.5%), and cognitive dysfunction (11.4%). Brain abnormalities were found in 59.3%. SVD was the most common (55.6%), followed by LVD (13%) and inflammatory-like lesions (6.5%). The most frequent SVD findings were WMH (53.7%), atrophy (18.5%), microbleeds (13.7%) and lacunes (11.1%). Cerebrovascular syndrome correlated with LVD ( p = 0.001) and microbleeds ( p = 0.002), cognitive dysfunction with WMH ( p = 0.045) and myelopathy with inflammatory-like lesions ( p = 0.020). Low C4 and CH50 correlated with inflammatory-like lesions ( p < 0.001, p = 0.019) and lupus anticoagulant with WMH ( p = 0.018), microbleeds ( p = 0.002) and atrophy ( p = 0.008). Conclusions Vascular disease is the hallmark of NPSLE. Certain syndromes and immunological patterns are prone to more extensive brain damage. MRI could provide significant clinical information and insights into the pathological substrate.
Despite the increasing aging population and the high prevalence of OSA in elderly adults, little is known about cognitive effects of OSA and the effectiveness of CPAP treatment. Therefore, this study ...investigated whether elderly patients with OSA present cognitive deficits and functional and structural alterations of the brain that could be improved by CPAP treatment.
This randomized, evaluator-blinded, parallel-group, single-center pilot study involved patients aged ≥ 65 years with newly-diagnosed severe OSA syndrome. Thirty-three patients were assigned to receive either conservative care (CC) or CPAP plus CC for 3 months. At baseline and 3 months after treatment, patients underwent a neuropsychologic evaluation and a functional and structural MRI study of connectivity within the default mode network (DMN) and of cortical thickness.
Neuropsychologic evaluation revealed no differences in cognitive performance between OSA groups at baseline. By contrast, after CPAP treatment, patients showed a significant improvement in episodic (between-group difference in change, 7.60; 95% CI, 1.66-13.55; P = .014) and short-term memory (between-group difference in change, 1.06; 95% CI, 0.10-2.01; P = .032) and in executive function (speed of mental processing, 5.74; 95% CI, 1.69-9.79; P = .007; mental flexibility, -47.64; 95% CI, -81.83 to -13.45; P = .008), whereas no changes were observed in the CC group. Neuroimaging revealed an increase in the connectivity in the right middle frontal gyrus after 3 months of CPAP treatment and a higher percentage of cortical thinning in the CC group. No association was seen between cognition and brain functional connectivity changes within the DMN.
Elderly patients with severe OSA who present with cognitive difficulties could benefit from CPAP treatment. Moreover, CPAP treatment increases the connectivity of the DMN and attenuates cortical thinning.
ClinicalTrials.gov; No.: NCT01826032; URL: www.clinicaltrials.gov.
The human cerebral cortex appears to shrink during adolescence. To delineate the dynamic morphological changes involved in this process, 52 healthy male and female adolescents (11-17 years old) were ...neuroimaged twice using magnetic resonance imaging, approximately 2 years apart. Using a novel morphometric analysis procedure combining the FreeSurfer and BrainVisa image software suites, we quantified global and lobar change in cortical thickness, outer surface area, the gyrification index, the average Euclidean distance between opposing sides of the white matter surface (gyral white matter thickness), the convex ("exposed") part of the outer cortical surface (hull surface area), sulcal length, depth, and width. We found that the cortical surface flattens during adolescence. Flattening was strongest in the frontal and occipital cortices, in which significant sulcal widening and decreased sulcal depth co-occurred. Globally, sulcal widening was associated with cortical thinning and, for the frontal cortex, with loss of surface area. For the other cortical lobes, thinning was related to gyral white matter expansion. The overall flattening of the macrostructural three-dimensional architecture of the human cortex during adolescence thus involves changes in gray matter and effects of the maturation of white matter.
Transcranial direct and alternating current stimulation (tDCS and tACS, respectively) entail capability to modulate human brain dynamics and cognition. However, the comparability of these approaches ...at the level of large-scale functional networks has not been thoroughly investigated. In this study, 44 subjects were randomly assigned to receive sham (
= 15), tDCS (
= 15), or tACS (
= 14). The first electrode (anode in tDCS) was positioned over the left dorsolateral prefrontal cortex, the target area, and the second electrode (cathode in tDCS) was placed over the right supraorbital region. tDCS was delivered with a constant current of 2 mA. tACS was fixed to 2 mA peak-to-peak with 6 Hz frequency. Stimulation was applied concurrently with functional magnetic resonance imaging (fMRI) acquisitions, both at rest and during the performance of a verbal working memory (WM) task. After stimulation, subjects repeated the fMRI WM task. Our results indicated that at rest, tDCS increased functional connectivity particularly within the default-mode network (DMN), while tACS decreased it. When comparing both fMRI WM tasks, it was observed that tDCS displayed decreased brain activity post-stimulation as compared to online. Conversely, tACS effects were driven by neural increases online as compared to post-stimulation. Interestingly, both effects primarily occurred within DMN-related areas. Regarding the differences in each fMRI WM task, during the online fMRI WM task, tACS engaged distributed neural resources which did not overlap with the WM-dependent activity pattern, but with some posterior DMN regions. In contrast, during the post-stimulation fMRI WM task, tDCS strengthened prefrontal DMN deactivations, being these activity reductions associated with faster responses. Furthermore, it was observed that tDCS neural responses presented certain consistency across distinct fMRI modalities, while tACS did not. In sum, tDCS and tACS modulate fMRI-derived network dynamics differently. However, both effects seem to focus on DMN regions and the WM network-DMN shift, which are highly affected in aging and disease. Thus, albeit exploratory and needing further replication with larger samples, our results might provide a refined understanding of how the DMN functioning can be externally modulated through commonly used non-invasive brain stimulation techniques, which may be of eventual clinical relevance.
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