Group Differences In Cortical Thickness Research Articles

Reduced orbitofrontal cortical thickness in male adolescents with internet addiction

BackgroundThe orbitofrontal cortex (OFC) has consistently been implicated in the pathology of both drug and behavioral addictions. However, no study to date has examined OFC thickness in internet addiction. In the current study, we investigated the existence of differences in cortical thickness of the OFC in adolescents with internet addiction. On the basis of recently proposed theoretical models of addiction, we predicted a reduction of thickness in the OFC of internet addicted individuals.FindingsParticipants were 15 male adolescents diagnosed as having internet addiction and 15 male healthy comparison subjects. Brain magnetic resonance images were acquired on a 3T MRI and group differences in cortical thickness were analyzed using FreeSurfer. Our results confirmed that male adolescents with internet addiction have significantly decreased cortical thickness in the right lateral OFC (p<0.05).ConclusionThis finding supports the view that the OFC alterations in adolescents with internet addiction reflect a shared neurobiological marker of addiction-related disorders in general.

The Cortical Signature of Amyotrophic Lateral Sclerosis

The aim of this study was to explore the pattern of regional cortical thickness in patients with non-familial amyotrophic lateral sclerosis (ALS) and to investigate whether cortical thinning is associated with disease progression rate. Cortical thickness analysis was performed in 44 ALS patients and 26 healthy controls. Group differences in cortical thickness and the age-by-group effects were assessed using vertex-by-vertex and multivariate linear models. The discriminatory ability of MRI variables in distinguishing patients from controls was estimated using the Concordance Statistics (C-statistic) within logistic regression analyses. Correlations between cortical thickness measures and disease progression rate were tested using the Pearson coefficient. Relative to controls, ALS patients showed a bilateral cortical thinning of the primary motor, prefrontal and ventral frontal cortices, cingulate gyrus, insula, superior and inferior temporal and parietal regions, and medial and lateral occipital areas. There was a significant age-by-group effect in the sensorimotor cortices bilaterally, suggesting a stronger association between age and cortical thinning in ALS patients compared to controls. The mean cortical thickness of the sensorimotor cortices distinguished patients with ALS from controls (C-statistic ≥0.74). Cortical thinning of the left sensorimotor cortices was related to a faster clinical progression (r = −0.33, p = 0.03). Cortical thickness measurements allowed the detection and quantification of motor and extramotor involvement in patients with ALS. Cortical thinning of the precentral gyrus might offer a marker of upper motor neuron involvement and disease progression.

Cortical Thickness and Folding Deficits in Conduct-Disordered Adolescents

Studies of pediatric conduct disorder (CD) have described frontal and temporal lobe structural abnormalities that parallel findings in antisocial adults. The purpose of this study was to examine previously unexplored cortical thickness and folding as markers for brain abnormalities in "pure CD"-diagnosed adolescents. On the basis of current frontotemporal theories, we hypothesized that CD youth would have thinner cortex or less cortical folding in temporal and frontal lobes than control subjects. We obtained T1-weighted brain structure images from 24 control and 19 CD participants aged 12 to 18 years, matched by gender and age. We measured group differences in cortical thickness and local gyrification index (regional cortical folding measure) using surface-based morphometry with clusterwise correction for multiple comparisons. The CD participants, compared with control subjects, showed both reduced cortical thickness and folding. Thinner cortex was located primarily in posterior brain regions, including left superior temporal and parietal lobes, temporoparietal junction and paracentral lobule, right superior temporal and parietal lobes, temporoparietal junction, and precuneus. Folding deficits were located mainly in anterior brain regions and included left insula, ventro- and dorsomedial prefrontal, anterior cingulate and orbitofrontal cortices, temporal lobe, right superior frontal and parietal lobes, and paracentral lobule. Our findings generally agree with previous CD volumetric studies but here show the unique contributions of cortical thickness and folding to gray matter reductions in pure CD in different brain regions.

Cortical thickness and VBM-DARTEL in late-life depression

Numerous studies have revealed structural brain changes in late life depression, mainly in white matter or whole lobes with few focussing just on grey matter (GM). The objective was to investigate GM changes in older depressed and similar aged healthy subjects using two different methods, cortical thickness in frontal lobe structures and voxel-based morphometry (VBM). Sixty eight subjects participated (30 healthy comparison subjects, 38 depressed) and underwent 3T T1 MR imaging as well as clinical and cognitive assessments. Frontal cortical thickness was measured using FreeSurfer while VBM was undertaken using the DARTEL algorithm in SPM8. Group differences in cortical thickness and GM volumes were assessed using ANCOVA. Effects of cortical thickness and VBM results on cognitive and depression variables were also investigated. No significant differences in frontal lobe cortical thickness were observed between groups (F(1, 62) ≤ 2.7, p ≥ 0.1). In addition, no significant relationships of cortical thickness on cognitive and depression scores were identified (partial correlation |r'|=0.01-0.31, p ≥ 0.06). VBM showed that GM volumes were indistinguishable between groups but significant age effects were apparent, independent of diagnosis. Results suggest that cortical GM changes in late life depression (LLD) are similar to healthy older subjects and appear to be related to age rather than cognitive or depressive symptoms. Changes to white matter and subcortical GM structures may be more relevant in explaining the underlying neurobiology of LLD.

Altered prefrontal and insular cortical thickness in adolescent marijuana users

Introduction There are limited data regarding the impact of marijuana (MJ) on cortical development during adolescence. Adolescence is a period of substantial brain maturation and cortical thickness abnormalities may be indicative of disruptions of normal cortical development. This investigation applied cortical-surface based techniques to compare cortical thickness measures in MJ using adolescents compared to non-using controls. Methods Eighteen adolescents with heavy MJ use and 18 non-using controls similar in age received MRI scans using a 3T Siemens scanner. Cortical reconstruction and volumetric segmentation was performed with FreeSurfer. Group differences in cortical thickness were assessed using statistical difference maps covarying for age and gender. Results Compared to non-users, MJ users had decreased cortical thickness in right caudal middle frontal, bilateral insula and bilateral superior frontal cortices. Marijuana users had increased cortical thickness in the bilateral lingual, right superior temporal, right inferior parietal and left paracentral regions. In the MJ users, negative correlations were found between frontal and lingual regions for urinary cannabinoid levels and between age of onset of use and the right superior frontal gyrus. Conclusion This is one of the first studies to evaluate cortical thickness in a group of adolescents with heavy MJ use compared to non-users. Our findings are consistent with prior studies that documented abnormalities in prefrontal and insular regions. Our results suggest that age of regular use may be associated with altered prefrontal cortical gray matter development in adolescents. Furthermore, reduced insular cortical thickness may be a biological marker for increased risk of substance dependence.

Regional cerebral cortical thinning in bipolar disorder

This study was conducted to explore differences in cortical thickness between subjects with bipolar disorder and healthy comparison subjects using cortical surface-based analysis. Brain magnetic resonance images were acquired from 25 subjects with bipolar disorder and 21 healthy comparison subjects. Cortical surface-based analysis was conducted using the Freesurfer application. Group differences in cortical thickness, defined by the distance from gray/white boundary to the pial surface, were assessed using statistical difference maps. Subjects with bipolar disorder exhibited significantly decreased cortical thickness in left cingulate cortex, left middle frontal cortex, left middle occipital cortex, right medial frontal cortex, right angular cortex, right fusiform cortex and bilateral postcentral cortices, relative to healthy comparison subjects (all p < 0.001). Duration of illness in bipolar subjects was inversely correlated with the cortical thickness of the left middle frontal cortex. Cortical thinning was present in multiple prefrontal cortices in bipolar disorder. There was also cortical thinning in sensory and sensory association cortices, which has not been reported in previous studies using region-of-interest or voxel-based morphometry methods. Cortical thinning observed in the current study may be related to impairment of emotional, cognitive, and sensory processing in bipolar disorder but longitudinal studies will be necessary to test this hypothesis.