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Establishing neurobiological markers of posttraumatic stress disorder (PTSD) is essential to aid in diagnosis and treatment development. Fear processing deficits are central to PTSD, and their neural signatures may be used as such markers.
Here, we conducted a meta-analysis of seven Pavlovian fear conditioning fMRI studies comparing 156 patients with PTSD and 148 trauma-exposed healthy controls (TEHC) using seed-based d-mapping, to contrast neural correlates of experimental phases, namely conditioning, extinction learning, and extinction recall.
Patients with PTSD, as compared to TEHCs, exhibited increased activation in the anterior hippocampus (extending to the amygdala) and medial prefrontal cortex during conditioning; in the anterior hippocampus-amygdala regions during extinction learning; and in the anterior hippocampus-amygdala and medial prefrontal areas during extinction recall. Yet, patients with PTSD have shown an overall decreased activation in the thalamus during all phases in this meta-analysis.
Findings from this metanalysis suggest that PTSD is characterized by increased activation in areas related to salience and threat, and lower activation in the thalamus, a key relay hub between subcortical areas. If replicated, these fear network alterations may serve as objective diagnostic markers for PTSD, and potential targets for novel treatment development, including pharmacological and brain stimulation interventions. Future longitudinal studies are needed to examine whether these observed network alteration in PTSD are the cause or the consequence of PTSD.
Delusional disorder has been the subject of very little investigation
using brain imaging.
To examine potential structural and/or functional brain abnormalities in
We used structural imaging (voxel-based morphometry, VBM) and functional
imaging (during performance of the n-back task and
whole-brain resting connectivity analysis) to examine 22 patients meeting
DSM-IV criteria for delusional disorder and 44 matched healthy
The patients showed grey matter reductions in the medial frontal/anterior
cingulate cortex and bilateral insula on unmodulated (but not on
modulated) VBM analysis, failure of de-activation in the medial
frontal/anterior cingulate cortex during performance of the
n-back task, and decreased resting-state connectivity
in the bilateral insula.
The findings provide evidence of brain abnormality in the medial
frontal/anterior cingulate cortex and insula in delusional disorder. A
role for the former region in the pathogenesis of delusions is consistent
with several other lines of evidence.
Cognitive–behavioural therapy (CBT) is considered to be effective for the symptoms of schizophrenia. However, this view is based mainly on meta-analysis, whose findings can be influenced by failure to consider sources of bias.
To conduct a systematic review and meta-analysis of the effectiveness of CBT for schizophrenic symptoms that includes an examination of potential sources of bias.
Data were pooled from randomised trials providing end-of-study data on overall, positive and negative symptoms. The moderating effects of randomisation, masking of outcome assessments, incompleteness of outcome data and use of a control intervention were examined. Publication bias was also investigated.
Pooled effect sizes were −0.33 (95% CI −0.47 to −0.19) in 34 studies of overall symptoms, −0.25 (95% CI −0.37 to −0.13) in 33 studies of positive symptoms and −0.13 (95% CI −0.25 to −0.01) in 34 studies of negative symptoms. Masking significantly moderated effect size in the meta-analyses of overall symptoms (effect sizes −0.62 (95% CI −0.88 to −0.35) v. −0.15 (95% CI −0.27 to −0.03), P = 0.001) and positive symptoms (effect sizes −0.57 (95% CI −0.76 to −0.39) v. −0.08 (95% CI −0.18 to 0.03), P<0.001). Use of a control intervention did not moderate effect size in any of the analyses. There was no consistent evidence of publication bias across different analyses.
Cognitive–behavioural therapy has a therapeutic effect on schizophrenic symptoms in the ‘small’ range. This reduces further when sources of bias, particularly masking, are controlled for.
Neurological soft signs (NSS) have been inconsistently reported in obsessive-compulsive disorder (OCD) but may make an impact on treatment response.
The current study examined the presence of NSS in two independent European samples of OCD patients (combined 85 patients and 88 matched healthy controls) using a standardized instrument and conducted a meta-analysis of all published studies identified in the literature with the aim to provide a more definitive answer to the question of whether OCD patients are characterized by increased NSS.
Both empirical studies found elevated NSS scores in patients compared with matched controls. The results of the meta-analysis, which included 15 studies (combined 498 patients and 520 controls) showed large effect sizes (Hedges' g=1.27, 95% confidence interval 0.80–1.75), indicating that OCD patients have significantly higher rates of NSS than matched controls on both sides of the body and in multiple domains (motor coordination, sensory integration and primitive reflexes). The results were robust and remained largely unchanged in our reliability analyses, which controlled for possible outliers. Meta-regression was employed to examine the role of potential variables of interest including sociodemographic variables, symptom severity, medication effects and the use of different instruments, but none of these variables was clearly associated with NSS.
As a group, OCD patients are characterized by increased rates of NSS, compared with healthy controls. However, their origins and potential clinical importance remain to be clarified. Future directions for research are discussed.
Schizo-affective disorder has not been studied to any significant extent using functional imaging. The aim of this study was to examine patterns of brain activation and deactivation in patients meeting strict diagnostic criteria for the disorder.
Thirty-two patients meeting Research Diagnostic Criteria (RDC) for schizo-affective disorder (16 schizomanic and 16 schizodepressive) and 32 matched healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups.
Controls showed activation in a network of frontal and other areas and also deactivation in the medial frontal cortex, the precuneus and the parietal cortex. Schizo-affective patients activated significantly less in prefrontal, parietal and temporal regions than the controls, and also showed failure of deactivation in the medial frontal cortex. When task performance was controlled for, the reduced activation in the dorsolateral prefrontal cortex (DLPFC) and the failure of deactivation of the medial frontal cortex remained significant.
Schizo-affective disorder shows a similar pattern of reduced frontal activation to schizophrenia. The disorder is also characterized by failure of deactivation suggestive of default mode network dysfunction.
We conducted a meta-analysis of voxel-based morphometry (VBM) studies in autism spectrum disorder (ASD) to clarify the changes in regional white-matter volume underpinning this condition, and generated an online database to facilitate replication and further analyses by other researchers.
PubMed, ScienceDirect, Web of Knowledge and Scopus databases were searched between 2002 (the date of the first white-matter VBM study in ASD) and 2010. Manual searches were also conducted. Authors were contacted to obtain additional data. Coordinates were extracted from clusters of significant white-matter difference between patients and controls. A new template for white matter was created for the signed differential mapping (SDM) meta-analytic method. A diffusion tensor imaging (DTI)-derived atlas was used to optimally localize the changes in white-matter volume.
Thirteen datasets comprising 246 patients with ASD and 237 healthy controls met inclusion criteria. No between-group differences were found in global white-matter volumes. ASD patients showed increases of white-matter volume in the right arcuate fasciculus and also in the left inferior fronto-occipital and uncinate fasciculi. These findings remained unchanged in quartile and jackknife sensitivity analyses and also in subgroup analyses (pediatric versus adult samples).
Patients with ASD display increases of white-matter volume in tracts known to be important for language and social cognition. Whether the results apply to individuals with lower IQ or younger age and whether there are meaningful neurobiological differences between the subtypes of ASD remain to be investigated.
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