Rich club and reward network connectivity as endophenotypes for alcohol dependence: a diffusion tensor imaging study.

We aimed to examine the whole-brain white matter connectivity and local topology of reward system nodes in patients with alcohol use disorder (AUD) and unaffected siblings, relative to healthy comparison individuals. Diffusion-weighted magnetic resonance imaging scans were acquired from 18 patients with AUD, 15 unaffected siblings of AUD patients and 15 healthy controls. Structural networks were examined using network-based statistic and connectomic analysis. Connectomic analysis showed a significant ordered difference in normalized rich club organization (AUD < Siblings < Controls). We also found rank ordered differences (Control > Sibling > AUD) for both nodal clustering coefficient and nodal local efficiency in reward system nodes, particularly left caudate, right putamen and left hippocampus. Network-based statistic analyses showed that AUD group had significantly weaker connectivity than controls in the right hemisphere, mostly in the edges connecting putamen and hippocampus with other brain regions. Our results suggest that reward system network abnormalities, especially in subcortical structures, and impairments in rich-club organization might be related to the familial predisposition for AUD.

Test-retest reliability of the novel 5-HT1B receptor PET radioligand [11C]P943.

PURPOSE: [(11)C]P943 is a novel, highly selective 5-HT1B PET radioligand. The aim of this study was to determine the test-retest reliability of [(11)C]P943 using two different modeling methods and to perform a power analysis with each quantification technique. METHODS: Seven healthy volunteers underwent two PET scans on the same day. Regions of interest (ROIs) were the amygdala, hippocampus, pallidum, putamen, insula, frontal, anterior cingulate, parietal, temporal and occipital cortices, and cerebellum. Two multilinear radioligand quantification techniques were used to estimate binding potential: MA1, using arterial input function data, and the second version of the multilinear reference tissue model analysis (MRTM2), using the cerebellum as the reference region. Between-scan percent variability and intraclass correlation coefficients (ICC) were used to assess test-retest reliability. We also performed power analyses to determine the method that would allow the least number of subjects using within-subject or between-subject study designs. A voxel-wise ICC analysis for MRTM2 BPND was performed for the whole brain and all the ROIs studied. RESULTS: Mean percent variability between two scans across regions ranged between 0.4 % and 12.4 % for MA1 BPND, 0.5 % and 11.5 % for MA1 BPP, 16.7 % and 28.3 % for MA1 BPF, and between 0.2 % and 5.4 % for MRTM2 BPND. The power analyses showed a greater number of subjects were required using MA1 BPF compared with other outcome measures for both within-subject and between-subject study designs. ICC values were the highest using MRTM2 BPND and the lowest with MA1 BPF in ten ROIs. Small regions and regions with low binding had lower ICC values than large regions and regions with high binding. CONCLUSION: Reliable measures of 5-HT1B receptor binding can be obtained using the novel PET radioligand [(11)C]P943. Quantification of 5-HT1B receptor binding with MRTM2 BPND and with MA1 BPP provided the least variability and optimal power for within-subject and between-subject designs.

Facial emotion recognition deficits in abstinent cannabis dependent patients.

BACKGROUND: Cannabis is clearly the most popular illicit drug in North America, Europe and in other parts of the world. Evidence is accumulating for the involvement of the endocannabinoid system in emotional processing. However, only few studies examined emotional processing in chronic, heavy cannabis users and these studies were performed in cannabis dependent patients who were abstinent for 12-48 hours. The aim of this study was to investigate facial emotion identification and discrimination abilities in patients with cannabis dependence who were abstinent for at least 1 month. METHODS: The study included 30 males with cannabis dependency according to DSM-IV criteria and who had been abstinent for at least 1 month and 30 healthy controls. All the subjects were evaluated with Facial Emotion Identification Test (FEIT) and Facial Emotion Discrimination Test (FEDT). RESULTS: The main finding of this study was the presence of deficits in both identification and discrimination of facial emotions in cannabis dependent patients during abstinence. In addition, when we examined negative and positive emotions separately, we found out that abstinent cannabis dependent patients performed significantly worse than controls in the identification of negative emotions but not positive emotions. CONCLUSIONS: Our findings indicate that facial emotion recognition deficits which have previously been observed in current cannabis users are still detectable in abstinent cannabis dependent patients and do not improve quickly with abstinence (an average of 3.2 months).

Prefrontal cortical response to emotional faces in individuals with major depressive disorder in remission.

Abnormalities in the response of the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) to negative emotional stimuli have been reported in acutely depressed patients. However, there is a paucity of studies conducted in unmedicated individuals with major depressive disorder in remission (rMDD) to assess whether these are trait abnormalities. To address this issue, 19 medication-free rMDD individuals and 20 healthy comparison (HC) participants were scanned using functional magnetic resonance imaging while performing an implicit emotion processing task in which they labeled the gender of faces depicting negative (fearful), positive (happy) and neutral facial expressions. The rMDD and HC groups were compared using a region-of-interest approach for two contrasts: fear vs. neutral and happy vs. neutral. Relative to HC, rMDD showed reduced activation in left OFC and DLPFC to fearful (vs. neutral) faces. Right DLPFC activation to fearful (vs. neutral) faces in the rMDD group showed a significant positive correlation with duration of euthymia. The findings support deficits in left OFC and DLPFC responses to negative emotional stimuli during euthymic periods of MDD, which may reflect trait markers of the illness or a 'scar' due to previous depression. Recovery may also be associated with compensatory increases in right DLPFC functioning.

Enhanced visual motion perception in major depressive disorder.

Major depressive disorder (MDD) is a mood disorder that is not traditionally considered to affect the visual system. However, recent findings have reported decreased cortical levels of the inhibitory neurotransmitter GABA in occipital cortex. To explore possible functional consequences of MDD on visual processing, we applied a psychophysical visual motion processing task in which healthy young adults typically exhibit impaired perceptual discrimination of large high-contrast stimuli. It has been suggested that this phenomenon, spatial suppression, is mediated by GABAergic center-surround antagonism in visual pathways. Based on previous findings linking MDD to occipital GABA dysfunction, we hypothesized that MDD patients would exhibit decreased spatial suppression, leading to the counterintuitive hypothesis of better psychophysical performance. Indeed, motion perception for typically suppressed stimuli was enhanced in patients with MDD compared with age-matched controls. Furthermore, the degree of spatial suppression correlated with an individual's illness load; patients with greater lifetime duration of depression exhibited the least spatial suppression and performed the best in the high-contrast motion discrimination task. Notably, this decrease in spatial suppression persisted beyond recovery and without the confound of acute illness or treatment; all patients had been clinically recovered and unmedicated for several months at the time of testing, suggesting that depression has ubiquitous consequences that may persist long after mood symptoms have receded. This finding raises the possibility that spatial suppression may represent a sensitive endophenotypic marker of trait vulnerability in MDD.

Cortical thickness and surface area as an endophenotype in bipolar disorder type I patients and their first-degree relatives.

OBJECTIVES: So far, few studies have investigated cortical thickness (CT) and surface area (SA) measures in bipolar disorder type I (BDI) in comparison to a high genetic risk group such as first-degree relatives (FR). This study aimed to examine CT and SA differences between BDI, FR and healthy controls (HC). METHODS: 3D T1 magnetic resonance images were acquired from 27 euthymic BDI patients, 24 unaffected FR and 29 HC. CT and SA measures were obtained with FreeSurfer version 5.3.0. Generalized estimating equations were used to compare CT and SA between groups. Group comparisons were repeated with restricting the FR group to 17 siblings (FR-SB) only. RESULTS: \Mean age in years was 36.3 ±â€¯9.5 for BDI, 32.1 ±â€¯10.9 for FR, 34.7 ±â€¯9.8 for FR-SB and 33.1 ±â€¯9.0 for HC group respectively. BDI patients revealed larger SA of left pars triangularis (LPT) compared to HC (p = .001). In addition, increased SA in superior temporal cortex (STC) in FR-SB group compared to HC was identified (p = .0001). CONCLUSIONS: Our result of increased SA in LPT of BDI could be a disease marker and increased SA in STC of FR-SB could be a marker related with resilience to illness.

Abnormal white matter integrity in synthetic cannabinoid users.

Synthetic cannabinoids have become increasingly popular in the last few years especially among adolescents and young adults. However, no previous studies have assessed the effects of synthetic cannabinoids on the structure of the human brain. Understanding the harms of synthetic cannabinoid use on brain structure is therefore crucial given its increasing use. Diffusion tensor imaging (DTI) was performed in 22 patients who used synthetic cannabinoids more than five times a week for at least 1 year and 18 healthy controls. Fractional anisotropy (FA) was significantly reduced in the cannabinoid group compared to controls in a cluster of white matter voxels spanning the left temporal lobe, subcortical structures and brainstem. This cluster was predominantly traversed by the inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, fornix, cingulum-hippocampus and corticospinal tracts. Long-term use of synthetic cannabinoids is associated with white matter abnormalities in adolescents and young adults. Disturbed brain connectivity in synthetic cannabinoid users may underlie cognitive impairment and vulnerability to psychosis.

Neuroanatomical correlates of genetic risk for bipolar disorder: A voxel-based morphometry study in bipolar type I patients and healthy first degree relatives.

BACKGROUND: Bipolar disorder (BD) is a highly heritable mental illness which is associated with neuroanatomical abnormalities. Investigating healthy individuals at high genetic risk for bipolar disorder may help to identify neuroanatomical markers of risk and resilience without the confounding effects of burden of illness or medication. METHODS: Structural magnetic resonance imaging scans were acquired from 30 euthymic patients with BD-I (BP), 28 healthy first degree relatives of BD-I patients (HR), and 30 healthy controls (HC). Data was analyzed using DARTEL for voxel based morphometry in SPM8. RESULTS: Whole-brain analysis revealed a significant main effect of group in the gray matter volume in bilateral inferior frontal gyrus, left parahippocampal gyrus, left lingual gyrus and cerebellum, posterior cingulate gyrus, and supramarginal gyrus (alphasim corrected (≤0.05 FWE)). Post-hoc t-tests showed that inferior frontal gyrus volumes were bilaterally larger both in BP and HR than in HC. BP and HR also had smaller cerebellar volume compared with HC. In addition, BP had smaller left lingual gyrus volume, whereas HR had larger left parahippocampal and supramarginal gyrus volume compared with HC. LIMITATIONS: This study was cross-sectional and the sample size was not large. All bipolar patients were on medication, therefore we were not able to exclude medication effects in bipolar group in this study. CONCLUSIONS: Our findings suggest that increased inferior frontal gyrus and decreased cerebellar volumes might be associated with genetic predisposition for bipolar disorder. Longitudinal studies are needed to better understand the predictive and prognostic value of structural changes in these regions.

Abnormal white matter integrity in long-term abstinent alcohol dependent patients.

A number of diffusion tensor imaging (DTI) studies have reported substantial white matter (WM) abnormalities in alcohol-dependent patients. These studies were usually performed in recovering alcohol-dependent patients who had been abstinent for days to several weeks. The current study was designed to examine WM microstructure and decision-making in a sample of long-term abstinent alcohol-dependent patients. The study included 12 subjects with alcohol dependence who had been abstinent for at least 6 months before testing and scanning and 13 healthy control subjects. The Iowa Gambling Task (IGT) was used to measure decision-making. We found that the long-term abstinent alcohol-dependent group had significantly higher radial and axial diffusivity (RD and AD, respectively) values in frontal, temporal and parietal WM than was found in the healthy control group despite showing no difference in fractional anisotropy (FA) values in comparison to controls. In conclusion, we found widespread WM changes in long-term abstinent alcohol-dependent patients compared with healthy controls. Our findings suggested that AD and RD should be included in analyses of DTI data in addition to the more commonly studied FA. In the current study, FA values of the detoxified alcoholics had recovered and were comparable to those of the controls, whereas significant changes in AD and RD were still observed in some clusters in the frontal, parietal and temporal lobes of detoxified alcoholics even after 27.8 months.

Abnormal white matter integrity and decision-making deficits in alcohol dependence.

To date, there is no study that explored the correlation of microstructural changes in the whole brain white matter (WM) and decision-making in alcohol dependent patients (ADP). In the present study, we applied Tract Based Spatial Statistics (TBSS) to study WM changes in ADP compared with healthy controls. We also tested whether there was any relationship between WM integrity and decision-making in ADP. The study included 17 inpatient ADP who had been abstinent for at least 2 weeks before testing and scanning and 16 healthy control subjects. The Iowa Gambling Task (IGT) was used to measure decision-making. Results for the IGT showed a significant group (ADP vs. control) by block interaction. Follow-up univariate analyses of variance showed that the groups were significantly different in the last 20 trails. Four significant clusters were found in which fractional anisotropy was significantly lower in ADP than in control subjects, including the corpus callosum and parietal, occipital and frontal regions. We found significant correlations between impaired IGT performance in the last 20 trials and WM integrity in these regions. Together, these results might help to explain observed decision making deficits in ADP.

Persistent ß2*-nicotinic acetylcholinergic receptor dysfunction in major depressive disorder.

BACKGROUND: Modulation of nicotinic acetylcholine receptors (nAChRs), specifically those containing the ß2 subunit, may be effective in treating patients with major depressive disorder. Using [123I]5-I-A-85380 single photon emission computed tomography (SPECT), the authors studied the availability of ß2-subunit-containing nAChRs (ß2*-nAChRs) in depressed patients. To understand its molecular basis, the authors also studied ß2*-nAChR binding in postmortem brain samples from depressed subjects. METHOD: The participants were 23 medication-free, nonsmoking subjects with familial, early-onset depression (eight acutely ill and 15 recovered) and 23 age- and gender-matched nonsmoking comparison subjects. Each received one [123I]5-I-A-85380 SPECT scan and an MRI scan. The availability of ß2*-nAChRs was quantified as VT/fP. Postmortem analysis of ß2*-nAChR binding was conducted with [123I]5-I-A-85380 on prefrontal cortex samples from 14 depressed subjects and 14 age-matched comparison subjects. RESULTS: The ß2*-nAChR availability in both the acutely ill and recovered depressed subjects was significantly lower across all brain regions than in the respective comparison subjects, and it was lower in the acutely ill subjects than in those who were recovered. In the depressed patients, ß2*-nAChR availability was significantly correlated with lifetime number of depressive episodes, trauma score, and anxiety score. There were no differences in ß2*-nAChR number between groups in the postmortem study. CONCLUSIONS: Depressed patients have lower ß2*-nAChR availability than do healthy subjects. The difference between ß2*-nAChR availability in vivo and in post-mortem samples may be analogous to data with dopaminergic PET ligands and dopamine receptor availability; lower receptor availability for the SPECT ligand could be caused by greater endogenous acetylcholine.

Levetiracetam in the management of bipolar depression: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To study the efficacy of adjunctive levetiracetam therapy compared with placebo in the treatment of subjects with depression with bipolar disorder. METHOD: This double-blind, placebo-controlled clinical trial randomly assigned outpatients with bipolar disorder type I and type II who were experiencing a major depressive episode (Structured Clinical Interview for DSM-IV Axis I Disorders-Clinician Version criteria) to treatment with either placebo or adjunctive levetiracetam (up to 2,500 mg/d flexibly dosed) for 6 weeks. The subjects were recruited from October 2005 to June 2008. The primary efficacy measure was mean change from baseline to week 6 in the Hamilton Depression Rating Scale (21-item). Secondary efficacy assessments included the Montgomery-Åsberg Depression Rating Scale, the Beck Depression Inventory, the Clinical Global Impressions-Bipolar Version scale, the Hamilton Anxiety Rating Scale, and the Young Mania Rating Scale. RESULTS: Of 42 subjects randomly assigned to placebo or drug, 32 received at least 1 postbaseline assessment and thus were included in the analysis. The mean (SD) levetiracetam daily dose at endpoint evaluation was 1,132 (425) mg/d. There was no significant difference in the mean change from baseline to week 6 in the Hamilton Depression Rating Scale scores for levetiracetam compared with placebo. There were no significant differences in any of the secondary outcome measures. CONCLUSIONS: Levetiracetam adjunctive therapy was not superior to placebo in the short-term treatment of subjects with depression with bipolar disorder in the population studied. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT00566150.

GABAergic contributions to the pathophysiology of depression and the mechanism of antidepressant action.

Increasing evidence suggests that abnormalities in amino neurotransmission are associated with the neurobiology of depression. Preclinical studies demonstrate that GABA modulating agents are active in commonly used rodent behavioral models of antidepressant activity, and that chronic administration of antidepressant drugs induces marked changes in GABAergic function. In humans, depressed patients have lower plasma, CSF and brain GABA concentrations than non-depressed comparison subjects. The recent discovery that several anticonvulsant and GABA-mimetic agents possess mood stabilizing and antidepressant properties has further increased interest in these findings. This review outlines the existing literature investigating the possible involvement of GABA in the neurobiology of depression and briefly highlights how this information may afford new targets for antidepressant drug development.