Microstructural Abnormalities of Basal Ganglia and Thalamus in Bipolar and Unipolar Disorders: A Diffusion Kurtosis and Perfusion Imaging Study

Abstract

ObjectiveBipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in subcorticalgray matter regions between BD and UD.MethodsThirty-five BD patients, 30 UD patients and 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr) and cerebral blood flow (CBF) were measured by using regions-of-interest analysis in the caudate, putamen and thalamus of the subcortical gray matter regions.ResultsUD exhibited differences from controls for DKI measures and CBF in the left putamen and caudate. BD showed differences from controls for DKI measures in the left caudate. Additionally, BD showed lower Ka in right putamen, higher MD in right caudate compared with UD. Receiver operating characteristic analysis revealed the Kr of left caudate had the highest predictive power for distinguishing UD from controls.ConclusionThe two disorders may have overlaps in microstructural abnormality in basal ganglia. The change of caudate may serve as a potential biomarker for UD.

Microstructural Alterations in Bipolar and Major Depressive Disorders: A Diffusion Kurtosis Imaging Study

“…Lower concentrations of choline and creatine compounds and N‐acetyl aspartate have been reported in the parietal cortex of BD patients and posterior cingulate cortex of MDD patients . Third, the findings of neuroimaging studies also suggest differences in cortical thickness, functional connectivity, and cerebral blood flow in the frontal, parietal, and temporal lobes between these two disorders . Three existing diffusion kurtosis imaging (DKI) studies also report lower axial kurtosis (AK) in the right putamen and higher mean diffusivity (MD) in the right caudate nucleus and superior cerebellar peduncle of BD patients than their MDD counterparts .…”

“…Third, the findings of neuroimaging studies also suggest differences in cortical thickness, functional connectivity, and cerebral blood flow in the frontal, parietal, and temporal lobes between these two disorders . Three existing diffusion kurtosis imaging (DKI) studies also report lower axial kurtosis (AK) in the right putamen and higher mean diffusivity (MD) in the right caudate nucleus and superior cerebellar peduncle of BD patients than their MDD counterparts . There have also been diffusion tensor imaging (DTI) studies that report lower fractional anisotropy (FA) in the anterior cingulate, corpus callosum, uncinate fasciculus, corticospinal tract, and superior longitudinal fasciculus in BD than MDD .…”

“…Its performance has been satisfactory and superior to DTI in identifying microstructural abnormalities in several neurodegenerative diseases and psychiatric disorders, including BD and MDD . As mentioned previously, the observations of the initial DKI studies are suggestive of microstructural differences between BD and MDD . Nevertheless, the existing DKI studies that attempted to identify or distinguish the microstructural alterations in BD and MDD are limited in number and fail to cover the whole brain (ie, the evaluation was limited to the gray matter nuclei and part of the cerebellum) .…”

“…As mentioned previously, the observations of the initial DKI studies are suggestive of microstructural differences between BD and MDD . Nevertheless, the existing DKI studies that attempted to identify or distinguish the microstructural alterations in BD and MDD are limited in number and fail to cover the whole brain (ie, the evaluation was limited to the gray matter nuclei and part of the cerebellum) . From the previous DTI and DKI reports of BD and MDD, these disorders can have different DKI characteristics in those areas still unexplored .…”

Diffusion Kurtosis Imaging of Microstructural Changes in Gray Matter Nucleus in Parkinson Disease

“…This is because the GM microstructure lacks evident directionality that the radial and axial directions will be random and highly influenced by noise (21). However, a variety of changed Kr, Dr, Ka, and Kr in GM continue to be reported in normal aging (9)(10)(11)(12)22), in Moyamoya Disease (23), in Bipolar Disorders (24), and in various neurodegenerative processes including Alzheimer's disease (25,26) and Parkinson's disease (27,28). In fact, some of the deep GMs are composed of both gray matter and white matter (10,29).…”