Differences in white matter abnormalities between bipolar I and II disorders

Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan.
Journal of Affective Disorders (Impact Factor: 3.38). 12/2010; 127(1-3):309-15. DOI: 10.1016/j.jad.2010.05.026
Source: PubMed


Although patients with bipolar I and II disorders exhibit heterogeneous clinical presentations and cognitive functions, it remains unclear whether these two subtypes have distinct neural substrates. This study aimed to differentiate the fiber abnormalities between bipolar I and II patients using diffusion tensor images.
Fourteen bipolar I patients, thirteen bipolar II patients, and twenty-one healthy subjects were recruited. Fractional anisotropy (FA) values calculated from diffusion tensor images were compared among groups using two-sample t-test analysis in a voxel-wise manner. Correlations between the mean FA value of each survived area and the clinical characteristics as well as the scores of neuropsychological tests were further analyzed.
Patients of both subtypes manifested fiber impairments in the thalamus, anterior cingulate, and inferior frontal areas, whereas the bipolar II patients showed more fiber alterations in the temporal and inferior prefrontal regions. The FA values of the subgenual anterior cingulate cortices for both subtypes correlated with the performance of working memory. The FA values of the right inferior frontal area of bipolar I and the left middle temporal area of bipolar II both correlated with executive function. For bipolar II patients, the left middle temporal and inferior prefrontal FA values correlated with the scores of YMRS and hypomanic episodes, respectively.
Our findings suggest distinct neuropathological substrates between bipolar I and II subtypes. The fiber alterations observed in the bipolar I patients were majorly associated with cognitive dysfunction, whereas those in the bipolar II patients were related to both cognitive and emotional processing.

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Available from: Jen-Chuen Hsieh
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    • "Compared to HC, both BD subgroups were shown to have FA reductions in the WM of the corpus callosum, cingulum and right frontal regions (Ha et al., 2011; Liu et al., 2010). A direct comparison between BD-I and BD-II indicated that BD-I have lower FA values in the right temporal WM (Ha et al., 2011) while BD-II have lower FA values in the right precuneus, frontal and prefrontal regions (Liu et al., 2010) and widespread prefrontal and temporal RD increase (Maller et al., 2014). Hence, we performed a cross-sectional study on DTI parameters of BD-I, BD-II and HC. "
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    ABSTRACT: Background: Diffusion tensor imaging (DTI) studies of bipolar disorder (BD) report contrasting results and are mainly focused on bipolar I (BD-I) samples. We aimed at investigating how and where DTI parameters differ between BD-I and bipolar II (BD-II) and between BD and healthy control subjects (HC). Methods: We conducted a tract-based spatial statistics analysis of DTI derived parameters, namely fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD) in a matched sample of 50 BD (25 BD-I and 25 BD-II) during the chronic course of the illness and 50 HC. Results: Compared to BD-I and HC, BD-II showed lower FA but no significant AD or RD differences in the right inferior longitudinal fasciculus (ILF). Both patient groups showed lower AD and RD in the left internal capsule and lower AD across the left ILF, the cortico-spinal tract within the right hemisphere and bilaterally in the cerebellum with respect to HC. Limitations: Patients were medicated at the time of scanning; the BD-II group had higher Hamilton Rating Scale for Depression scores than the BD-I group. Conclusions: BD-II patients differ from BD-I in the ILF. Both BD subtypes showed widespread white matter (WM) changes in the internal capsule, cortico-spinal tract and cerebellum. The loss of WM integrity in BD-II might be due to demyelination whereas WM changes common to both subgroups could be attributable to axonal damage.
    Full-text · Article · Sep 2015 · Journal of Affective Disorders
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    • "There are few studies that have investigated subjects with Type I and Type II separately or used a whole brain approach rather than an a priori region of interest approach. For example, Ha et al. (2011) found reduced FA in the corpus callosum (CC), cingulate and right prefrontal regions, and apparent diffusion coefficient (ADC) increase in the medial frontal, anterior cingulate, insular and temporal regions when compared to controls; they also reported FA decrease in those with BD Type I in the right temporal WM and an ADC increase in the frontal, temporal, parietal and thalamic regions, compared to the BD Type II groups, suggesting that relative sparing of the dorsal system and long association fibers may differentiate BD Type II from Type I. Liu et al. (2010) imaged 14 BD Type I and 13 BD Type II patients (and matched controls) and reported that patients of both subtypes manifested fiber impairments in the thalamus, anterior cingulate, and inferior frontal areas, whereas, as mentioned above, the BD Type II patients showed more fiber alterations in the temporal and inferior prefrontal regions. By conducting both volumetric and diffusion analyses, the current study uses both techniques to explore specific regions/ circuits. "
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    ABSTRACT: Background Bipolar disorder (BD) is a debilitating psychiatric disorder affecting millions of people worldwide with mean time to diagnosis estimated to be at least 10 years. Whilst many brain imaging studies have compared those with BD to controls, few have attempted to investigate differences between BD Type I and II and matched controls. Methods Thirty-one patients with BD (16 Type I and 15 Type II) and 31 matched healthy controls were MRI brain scanned with conventional T1-weighted and diffusion tensor imaging methods. Results There was significantly reduced regional brain volume and thickness among the BD subjects, but also between BD Type I when compared to Type II. White matter integrity also differed between the groups and BD severity correlated significantly with regional brain volume and thickness. Limitations Future investigations will consider length of time each BD patient had been diagnosed with BD, as well as assessing controls for family history of psychiatric illness, specifically BD. Similarly, genetic assessment will be conducted as well. Conclusions These findings suggest that there are not only regional brain volumetric, thickness and white matter integrity differences between BD and matched controls, but also between those with BD Type I and Type II, such that reduced regional brain volume may underlie BD Type I whereas white matter integrity is more altered in BD Type II.
    Full-text · Article · Dec 2014 · Journal of Affective Disorders
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    • "Bipolar disorder (BD) is a devastating mood disorder with up to 4–6% lifetime prevalence in adults (Johnson and Johnson, 2014). Various brain regions have been implicated in BD, including reduced total brain volume (TBV) (Bora et al., 2010), compromised white matter (WM) integrity (Liu et al., 2010), and altered blood flow (Vargas et al., 2013). Significant findings have been noted in the frontal, parietal, occipital and temporal lobes in those with BD Type I and Type II, including the hippocampus (Rimol et al., 2010, 2012; Foland-Ross et al., 2011; Elvsashagen et al., 2013; Liang et al., 2013). "
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    ABSTRACT: Differing levels of occipital lobe asymmetry and enlarged lateral ventricles have been reported within patients with bipolar disorder (BD) compared with healthy controls, suggesting different rates of occipital bending (OB). This may exert pressure on subcortical structures, such as the hippocampus, reduced among psychiatric patients. We investigated OB prevalence in 35 patients with BD and 36 healthy controls, and ventricular and occipital volumes. Prevalence was four times higher among BD patients (12/35 [34.3%]) than in control subjects (3/36 [8.3%]), as well as larger lateral ventricular volumes. Furthermore, we found OB to relate to left-to-right ventricular and occipital lobe volume ratios. Those with OB also had reduced left-to- right hippocampal volume ratios. The results suggest that OB is more common among BD patients than healthy subjects, and prevalent in both BD Type I and Type II patients. We posit that anomalies in neural pruning or ventricular enlargement may precipitate OB, consequently resulting in one occipital lobe twisting around the other. Although the clinical implications of these results are unclear, the study suggests that asymmetrical ventricular volume matched with a pattern of oppositely asymmetrical occipital volume is related to OB and may be a marker of psychiatric illness.
    Full-text · Article · Nov 2014 · Psychiatry Research: Neuroimaging
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