Abnormal white matter microstructure in drug-naive first episode schizophrenia patients before and after eight weeks of antipsychotic treatment.
Abnormal white matter integrity has been reported among first episode schizophrenia patients. However, findings on whether it can be reversed by short-term antipsychotic medications are inconsistent.
Diffusion tensor imaging (DTI) was obtained from 55 drug-naive first episode schizophrenia patients and 61 healthy controls, and was repeated among 25 patients and 31 controls after 8 weeks during which patients were medicated with antipsychotics. White matter integrity is measured using fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). These measures showing a group difference by Tract-based spatial statistics (TBSS) at baseline were extracted for longitudinal comparisons.
At baseline, patients exhibited lower FA, higher MD and higher RD versus controls in forceps, left superior longitudinal fasciculus, inferior fronto-occipital fasciculus, left corticospinal tract, left uncinate fasciculus, left anterior thalamic radiation, and bilateral inferior longitudinal fasciculi. FA values of schizophrenia patients correlated with their negative symptoms (r=-0.412, P=0.002), working memory (r=0.377, P=0.005) and visual learning (r=0.281, P=0.038). The longitudinal changes in DTI indices in these tracts did not differ between patients and controls. However, among the patients the longitudinal changes in FA values in left superior longitudinal fasciculus correlated with the change of positive symptoms (r=-0.560, p=0.004), and the change of processing speed (r=0.469, p=0.018).
White matter deficits were validated in the present study by a relatively large sample of medication naïve and first episode schizophrenia patients. They could be associated with negative symptoms and cognitive impairment, whereas improvement in white matter integrity of left superior longitudinal fasciculus correlated with improvement in psychosis and processing speed. Further examination of treatment-related changes in white matter integrity may provide clues to the mechanism of antipsychotic response and provide a biomarker for clinical studies.
Zeng B
，Ardekani BA
，Tang Y
，Zhang T
，Zhao S
，Cui H
，Fan X
，Zhuo K
，Li C
，Xu Y
，Goff DC
，Wang J
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Analysis of fractional anisotropy and mean diffusivity in refractory and non-refractory idiopathic generalized epilepsies.
To compare white matter bundles and fiber tract changes in seizure-free and non-seizure-free idiopathic generalized epilepsy (IGE) patients.
Forty adult patients with IGE underwent a 3 T brain MRI with DTI sequences. According to seizure control status, eighteen patients were classified as refractory (R) if they had presented at least one incapacitating seizure in the previous six months, while on appropriate antiepileptic drug treatment. Twenty two seizure-free patients with adequate seizure control were considered non-refractory (NR). We compared fractional anisotropy (FA) and mean diffusivity (MD) values in sixteen white matter tracts in the R and NR groups, and in twenty healthy subjects.
R and NR groups did not differ in gender, age and education. We found decreased FA in two tracts in the R group (forceps major and right uncinate fasciculus) and approaching statistical significance in two tracts in the NR group (right cingulate gyrus and right uncinate fasciculus) group, as well as increased MD in six tracts in the R group (forceps minor, left thalamic anterior radiation, right inferior longitudinal fasciculus, right longitudinal superior parietal and temporal fasciculi, and right cingulate gyrus) and in five tracts in the NR group (forceps minor, left thalamic anterior radiation, right inferior longitudinal fasciculus, right longitudinal superior parietal and temporal fasciculi), compared to controls. No differences were noted comparing FA and MD values between R and NR groups.
In our patient population, refractory IGE patients on adequate antiepileptic drug treatment did not present more severe white matter tract involvement compared to non-refractory patients.
Lobato M
，Garcia L
，Amaro E Jr
，Otaduy M
，Jorge C
，Castro LH
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Clinical characteristics of post-stroke basal ganglia aphasia and the study of language-related white matter tracts based on diffusion spectrum imaging.
Stroke often damages the basal ganglia, leading to atypical and transient aphasia, indicating that post-stroke basal ganglia aphasia (PSBGA) may be related to different anatomical structural damage and functional remodeling rehabilitation mechanisms. The basal ganglia contain dense white matter tracts (WMTs). Hence, damage to the functional tract may be an essential anatomical structural basis for the development of PSBGA.
We first analyzed the clinical characteristics of PSBGA in 28 patients and 15 healthy controls (HCs) using the Western Aphasia Battery and neuropsychological test batteries. Moreover, we investigated white matter injury during the acute stage using diffusion magnetic resonance imaging scans for differential tractography. Finally, we used multiple regression models in correlation tractography to analyze the relationship between various language functions and quantitative anisotropy (QA) of WMTs.
Compared with HCs, patients with PSBGA showed lower scores for fluency, comprehension (auditory word recognition and sequential commands), naming (object naming and word fluency), reading comprehension of sentences, Mini-Mental State Examination, and Montreal Cognitive Assessment, along with increased scores in Hamilton Anxiety Scale-17 and Hamilton Depression Scale-17 within 7 days after stroke onset (P < 0.05). Differential tractography revealed that patients with PSBGA had damaged fibers, including in the body fibers of the corpus callosum, left cingulum bundles, left parietal aslant tracts, bilateral superior longitudinal fasciculus II, bilateral thalamic radiation tracts, left fornix, corpus callosum tapetum, and forceps major, compared with HCs (FDR < 0.02). Correlation tractography highlighted that better comprehension was correlated with a higher QA of the left inferior fronto-occipital fasciculus (IFOF), corpus callosum forceps minor, and left extreme capsule (FDR < 0.0083). Naming was positively associated with the QA of the left IFOF, forceps minor, left arcuate fasciculus, and uncinate fasciculus (UF) (FDR < 0.0083). Word fluency of naming was also positively associated with the QA of the forceps minor, left IFOF, and thalamic radiation tracts (FDR < 0.0083). Furthermore, reading was positively correlated with the QA of the forceps minor, left IFOF, and UF (FDR < 0.0083).
PSBGA is primarily characterized by significantly impaired word fluency of naming and preserved repetition abilities, as well as emotional and cognitive dysfunction. Damaged limbic pathways, dorsally located tracts in the left hemisphere, and left basal ganglia pathways are involved in PSBGA pathogenesis. The results of connectometry analysis further refine the current functional localization model of higher-order neural networks associated with language functions.
Han Y
，Jing Y
，Li X
，Zhou H
，Deng F
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ResearchGate
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钛学术
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