Increased white matter connectivity in euthymic bipolar patients: diffusion tensor tractography between the subgenual cingulate and the amygdalo-hippocampal complex (original) (raw)
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Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 2016
To review the available data on diffusion tensor imaging (DTI) of subjects with bipolar disorder (BD), with a particular focus on fractional anisotropy (FA) in white matter (WM) tracts. The PubMed/MEDLINE database was searched for relevant articles, which were included in a systematic review of the literature. FA reductions and WM abnormalities were divided anatomically into three groups: commissural tracts, association tracts, and projection tracts. Eighteen studies met the inclusion criteria. The corpus callosum was the main impaired commissural tract as demonstrated by FA reductions. Five studies reported FA reductions in the cingulum. Two studies reported decreased FA in the anterior thalamic radiation, and one in the corticospinal tract. Conversely, three studies found increased FA values in WM tracts involved in BD pathophysiology. Despite considerable heterogeneity, these results indicate a direct link between executive cognitive functioning and abnormal WM microstructural in...
NeuroImage. Clinical, 2013
Bipolar disorder (BD) is a chronic mental illness characterized by severe disruptions in mood and cognition. Diffusion tensor imaging (DTI) studies suggest that white matter (WM) tract abnormalities may contribute to the clinical hallmarks of the disorder. Using DTI and whole brain voxel-based analysis, we mapped the profile of WM anomalies in BD. All patients in our sample were euthymic and lithium free when scanned. Diffusion-weighted and T1-weighted structural brain images were acquired from 23 lithium-free euthymic subjects with bipolar I disorder and 19 age- and sex-matched healthy control subjects on a 1.5 T MRI scanner. Scans were processed to provide measures of fractional anisotropy (FA) and mean and radial diffusivity (MD and RD) at each WM voxel, and processed scans were nonlinearly aligned to a customized brain imaging template for statistical group comparisons. Relative to controls, the bipolar group showed widespread regions of lower FA, including the corpus callosum, ...
Psychiatry and clinical neurosciences, 2017
To compare white matter structural changes in specific tracts by diffusion tensor imaging (DTI) tractography in patients of bipolar disorder I, non-ill first degree relatives of the patients, and healthy controls. In a cross sectional study, we studied right-handed subjects consisting of 16 euthymic bipolar disorder I patients, 15 first degree relatives and 15 healthy controls. The anterior thalamic radiation, uncinate fasciculus, corpus callosum, and cingulum bundle were reconstructed by DTI tractography. Mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were compared for group differences followed by post hoc analysis. The three groups did not differ in terms of socio-demographic variables. There were significant group differences in the FA values between the bipolar disorder I, first degree relatives and the healthy control groups for corpus callosum, dorsal part of right cingulum bundle, hippocampal part of cingulum bundle bilaterally, and uncinate ...
White matter abnormalities observed in bipolar disorder: a diffusion tensor imaging study
Bipolar Disorders, 2007
Neuroimaging technology has provided a number of new methods that have significantly advanced our knowledge of structural and functional deficits associated with psychiatric illnesses. In bipolar disorder (BPD), one of the most frequently reported brain abnormalities is the appearance of white matter hyperintensities (WMHs) (1-4), although non-significant differences in the prevalence or severity of WMHs between bipolar patients and healthy comparison subjects have also been reported (5). It has been hypothesized that WMHs result from localized changes in water content, which may play an important role in the neurocognitive deficits observed in BPD (6). Results from morphometry studies conducted in bipolar patients have been more mixed, with some studies documenting no overall differences in white matter volume between bipolar patients and controls (7, 8), several reporting significantly reduced white matter volume in bipolar I disorder (9, 10), and others reporting a trend for decreased white matter volume in first Yurgelun-Todd DA, Silveri MM, Gruber SA, Rohan ML, Pimentel PJ. White matter abnormalities observed in bipolar disorder: a diffusion tensor imaging study.
Abnormal frontal cortex white matter connections in bipolar disorder: A DTI tractography study
Journal of Affective Disorders, 2011
Objective: In bipolar disorder, white matter abnormalities have been reported with region-ofinterest and voxel-based methods; however, deficits in specific white matter tracts cannot be localized by these methods. Therefore, in this study, we aimed to investigate the white matter tracts that mediate connectivity of the frontal cortex using diffusion tensor imaging (DTI) tractography. Methods: Eighteen patients with bipolar disorder and sixteen age-and gender-matched healthy subjects underwent DTI examinations. Frontal cortex white matter tracts, including the anterior thalamic radiation (ATR), uncinate fasciculus (UF), superior longitudinal fasciculus (SLF), cingulum, and inferior fronto-occipital fasciculus (IFO) were reconstructed by DTI tractography, and we calculated the mean fractional anisotropy (FA) for each fiber tract. The values were compared between groups by repeated measures analysis of variance with age and gender as covariates, which allowed us to investigate significant differences between the tracts. Results: When compared with healthy controls, the patients with bipolar disorder showed significantly decreased FA in the ATR and UF, and a trend towards lower FA in the SLF and cingulum. However, there were no FA differences between groups in the IFO. Conclusions: Our study indicates that bipolar patients show abnormalities within white matter tracts connecting the frontal cortex with the temporal and parietal cortices and the frontosubcortical circuits. These findings suggest that alterations in the connectivity of white matter tracts in the frontal cortex might contribute to the neuropathology of bipolar disorder.