Proper name retrieval and structural integrity of cerebral cortex in midlife: A cross-sectional study

There is currently little understanding on whether retrieval of proper names differs in midlife compared to young adulthood and if so, whether the age differences in this ability are associated with differences in structural integrity of the cerebral cortex. To answer these questions, we studied retrieval of proper names in 115 cognitively healthy middle-aged persons (49.7, ±3.2), comparing their performance on a tip-of-the-tongue (TOT) task with that of 68 young persons (25.4, ±3.5) from the Cam-Can data repository (http://www.mrc-cbu.cam.ac.uk/datasets/camcan/). Grey matter (GM) density and cortical thickness were used as indices of structural integrity of the cerebral cortex. The middle-aged (MA) group experienced more TOTs during proper names retrieval than young adults (YA), (t = 3.789, p < .005) and had considerably less GM density and cortical thickness across a range of brain areas bilaterally. Small clusters in left BA 45 and right BA 44 (cortical thickness) and in right BA 40 (volumetry) revealed group differences when accounting for TOTs. However, we observed no correlations between MA's TOT scores and GM volumes or cortical thickness of the brain regions typically reported as implicated in retrieval of proper names: left anterior temporal lobe, left insula, and left superior and middle temporal gyri.

Grey matter anomalies in drug-naïve childhood absence epilepsy: A voxel-based morphometry study with MRI at 3.0T

BACKGROUND

Little is known, so far, about the cerebral structural abnormalities in drug-naïve patients with childhood absence epilepsy (CAE). We aimed to investigate regional grey matter (GM) volume differences using voxel-based morphometry (VBM) in patients and closely matched healthy control subjects.

METHODS

Twenty drug-naïve patients diagnosed with CAE and 20 age- and gender-matched healthy subjects were recruited. All participants underwent structural MRI scans with a 3.0T MR system. The differences in regional GM volumes between the two groups were determined by VBM analysis. Additional regression analyses were performed to identify any associations between regional GM volume and clinical seizure variables.

RESULTS

Compared with controls, the patients with CAE showed less GM volume in the bilateral thalami. Furthermore, the GM volume in the bilateral thalami was negatively correlated with disease duration and age of onset in the CAE group.

CONCLUSIONS

By excluding the potential effect of medication on brain structures, our study demonstrates less GM volume in the bilateral thalami in drug-naïve patients with idiopathic CAE. Our study further provides structural neuroimaging evidence on the pathophysiology of absence seizures.

Spontaneous neural activity changes after bariatric surgery: A resting-state fMRI study

BACKGROUND

Metabolic disorders associated with obesity could lead to alterations in brain structure and function. Whether these changes can be reversed after weight loss is unclear. Bariatric surgery provides a unique opportunity to address these questions because it induces marked weight loss and metabolic improvements which in turn may impact the brain in a longitudinal fashion. Previous studies found widespread changes in grey matter (GM) and white matter (WM) after bariatric surgery. However, findings regarding changes in spontaneous neural activity following surgery, as assessed with the fractional amplitude of low frequency fluctuations (fALFF) and regional homogeneity of neural activity (ReHo), are scarce and heterogenous. In this study, we used a longitudinal design to examine the changes in spontaneous neural activity after bariatric surgery (comparing pre- to post-surgery), and to determine whether these changes are related to cardiometabolic variables.

METHODS

The study included 57 participants with severe obesity (mean BMI=43.1 ± 4.3 kg/m²) who underwent sleeve gastrectomy (SG), biliopancreatic diversion with duodenal switch (BPD), or Roux-en-Y gastric bypass (RYGB), scanned prior to bariatric surgery and at follow-up visits of 4 months (N = 36), 12 months (N = 29), and 24 months (N = 14) after surgery. We examined fALFF and ReHo measures across 1022 cortical and subcortical regions (based on combined Schaeffer-Xiao parcellations) using a linear mixed effect model. Voxel-based morphometry (VBM) based on T1-weighted images was also used to measure GM density in the same regions. We also used an independent sample from the Human Connectome Project (HCP) to assess regional differences between individuals who had normal-weight (N = 46) or severe obesity (N = 46).

RESULTS

We found a global increase in the fALFF signal with greater increase within dorsolateral prefrontal cortex, precuneus, inferior temporal gyrus, and visual cortex. This effect was more significant 4 months after surgery. The increase within dorsolateral prefrontal cortex, temporal gyrus, and visual cortex was more limited after 12 months and only present in the visual cortex after 24 months. These increases in neural activity measured by fALFF were also significantly associated with the increase in GM density following surgery. Furthermore, the increase in neural activity was significantly related to post-surgery weight loss and improvement in cardiometabolic variables, such as blood pressure. In the independent HCP sample, normal-weight participants had higher global and regional fALFF signals, mainly in dorsolateral/medial frontal cortex, precuneus and middle/inferior temporal gyrus compared to the obese participants. These BMI-related differences in fALFF were associated with the increase in fALFF 4 months post-surgery especially in regions involved in control, default mode and dorsal attention networks.

CONCLUSIONS

Bariatric surgery-induced weight loss and improvement in metabolic factors are associated with widespread global and regional increases in neural activity, as measured by fALFF signal. These findings alongside the higher fALFF signal in normal-weight participants compared to participants with severe obesity in an independent dataset suggest an early recovery in the neural activity signal level after the surgery.

Brain Structural Correlates of Intelligence in Attention Deficit Hyperactivity Disorder (ADHD) Individuals

Introduction

Neuroimaging evidence has shown the relationship of intelligence with several structural brain properties in normal individuals. However, this relationship with attention deficit hyperactivity disorder (ADHD) needs to be investigated.

Methods

We estimated grey matter (GM) density of the brain using magnetic resonance imaging (MRI) scan on 56 ADHD individuals, including 30 combined individuals (Mean±SD age: 10.44±2.41, intelligence quotient: [IQ]=112.13±13.15, male, 24 right hands) and 26 inattentive individuals (mean age =11.39±2.1, IQ=107.44±13.98, male, 28 right hands) as well as 30 IQ matched healthy control group (mean age=11.08±2.15, IQ=115±13.56, male, 23 right hands).

Results

In this study, two statistical approaches were used. In the first approach, region-based as well as the whole association patterns between full-scale IQ and GM were computed and compared between groups. The second approach was to examine the differential pattern of GM density without considering IQ in three groups.

Conclusion

Results showed significant differences between the ADHD group and the control. This finding could indicate that intelligence is not purely based on the density of GM in certain brain regions; it is a dynamic phenomenon and drastically changes neurodevelopmental disorders.

Highlights

In ADHDs as compared to healthy controls the relation between GM and IQ was decreased at right hemisphere;In ADHDs as compared to healthy controls the relation between GM and IQ was increased at left hemisphere;Differenceses of the observed relation between control group and IQ matched ADHDs suggest a compensatory mechanism in ADHDs to maintaine an adequate cognitive performance;GM is not the only determiner of intelligence. IQ score may be affected by neural dynamic of the brain; therefore, the structural covariate could be a better alternative for GM density.

Plain Language Summary

In this study, we estimated the relation between GM density and IQ score in 2 subtypes of ADHD (combined and inattentive) and IQ matched healthy control group. We compared the association between groups and found that the pattern of association in ADHDs were different from controls. In the other words, the decreased association at right hemisphere, were compensated by increased association at left hemisphere in ADHDs to maintaine adequate performance. We conclude that, the brain structure is not the single determiner of intelligence, rather intelligence may underpine by neural dynamics of the brain. Therefore, the structural covariate may be a better alternative for GM density.

Right superior frontal gyrus: A potential neuroimaging biomarker for predicting short-term efficacy in schizophrenia

Antipsychotic drug treatment for schizophrenia (SZ) can alter brain structure and function, but it is unclear if specific regional changes are associated with treatment outcome. Therefore, we examined the effects of antipsychotic drug treatment on regional grey matter (GM) density, white matter (WM) density, and functional connectivity (FC) as well as associations between regional changes and treatment efficacy. SZ patients (n = 163) and health controls (HCs) (n = 131) were examined by structural magnetic resonance imaging (sMRI) at baseline, and a subset of SZ patients (n = 77) were re-examined after 8 weeks of second-generation antipsychotic treatment to assess changes in regional GM and WM density. In addition, 88 SZ patients and 81 HCs were examined by resting-state functional MRI (rs-fMRI) at baseline and the patients were re-examined post-treatment to examine FC changes. The Positive and Negative Syndrome Scale (PANSS) and MATRICS Consensus Cognitive Battery (MCCB) were applied to measure psychiatric symptoms and cognitive impairments in SZ. SZ patients were then stratified into response and non-response groups according to PANSS score change (≥50 % decrease or <50 % decrease, respectively). The GM density of the right cingulate gyrus, WM density of the right superior frontal gyrus (SFG) plus 5 other WM tracts were reduced in the response group compared to the non-response group. The FC values between the right anterior cingulate and paracingulate gyrus and left thalamus were reduced in the entire SZ group (n = 88) after treatment, while FC between the right inferior temporal gyrus (ITG) and right medial superior frontal gyrus (SFGmed) was increased in the response group. There were no significant changes in regional FC among the non-response group after treatment and no correlations with symptom or cognition test scores. These findings suggest that the right SFG is a critical target of antipsychotic drugs and that WM density and FC alterations within this region could be used as potential indicators in predicting the treatment outcome of antipsychotics of SZ.