Prefrontal lobe dysfunction predicts treatment response in medication-naive first-episode schizophrenia

Neuroimaging in schizophrenia: A review article

In this review article we have consolidated the imaging literature of patients with schizophrenia across the full spectrum of modalities in radiology including computed tomography (CT), morphologic magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and magnetoencephalography (MEG). We look at the impact of various subtypes of schizophrenia on imaging findings and the changes that occur with medical and transcranial magnetic stimulation (TMS) therapy. Our goal was a comprehensive multimodality summary of the findings of state-of-the-art imaging in untreated and treated patients with schizophrenia. Clinical imaging in schizophrenia is used to exclude structural lesions which may produce symptoms that may mimic those of patients with schizophrenia. Nonetheless one finds global volume loss in the brains of patients with schizophrenia with associated increased cerebrospinal fluid (CSF) volume and decreased gray matter volume. These features may be influenced by the duration of disease and or medication use. For functional studies, be they fluorodeoxyglucose positron emission tomography (FDG PET), rs-fMRI, task-based fMRI, diffusion tensor imaging (DTI) or MEG there generally is hypoactivation and disconnection between brain regions. However, these findings may vary depending upon the negative or positive symptomatology manifested in the patients. MR spectroscopy generally shows low N-acetylaspartate from neuronal loss and low glutamine (a neuroexcitatory marker) but glutathione may be elevated, particularly in non-treatment responders. The literature in schizophrenia is difficult to evaluate because age, gender, symptomatology, comorbidities, therapy use, disease duration, substance abuse, and coexisting other psychiatric disorders have not been adequately controlled for, even in large studies and meta-analyses.

Precuneus and insular hypoactivation during cognitive processing in first-episode psychosis: Systematic review and meta-analysis of fMRI studies

INTRODUCTION

The neural correlates of the cognitive dysfunction in first-episode psychosis (FEP) are still unclear. The present review and meta-analysis provide an update of the location of the abnormalities in the fMRI-measured brain response to cognitive processes in individuals with FEP.

METHODS

Systematic review and voxel-based meta-analysis of cross-sectional fMRI studies comparing neural responses to cognitive tasks between individuals with FEP and healthy controls (HC) according to PRISMA guidelines.

RESULTS

Twenty-six studies were included, comprising 598 individuals with FEP and 567 HC. Individual studies reported statistically significant hypoactivation in the dorsolateral prefrontal cortex (6 studies), frontal lobe (8 studies), cingulate (6 studies) and insula (5 studies). The meta-analysis showed statistically significant hypoactivation in the left anterior insula, precuneus and bilateral striatum.

CONCLUSIONS

While the studies tend to highlight frontal hypoactivation during cognitive tasks in FEP, our meta-analytic results show that the left precuneus and insula primarily display aberrant activation in FEP that may be associated with salience attribution to external stimuli and related to deficits in perception and regulation.

White matter correlates of impulsivity in frontal lobe and their associations with treatment response in first-episode schizophrenia

BACKGROUND

It is known that increased impulsivity in schizophrenia patients causes poor treatment outcomes by increasing cost, stigma, hospitalization, treatment challenge, and physical harm. Dysfunction in the prefrontal cortex appears to be involved in the impulsivity associated with schizophrenia; nonetheless, there is a dearth of research on specific white matter alterations in the prefrontal cortex related to impulsivity.

METHODS

We enrolled in the present study 119 first-episode schizophrenia patients. We measured their symptom severity at baseline and after eight weeks of treatment, using the positive and negative syndrome scale. We performed neuroimaging analysis using the Tract-Based Spatial Statistics program and by specifying the prefrontal white matter as a region of interest.

RESULTS

In voxel-wise correlational analysis, we observed white matter regions showing significant positive correlations with poor impulse control scores, in both the right dorsolateral prefrontal cortex and the right frontal pole region. The fractional anisotropy values of these areas correlated positively with symptom severity at baseline. Moreover, after eight weeks, treatment non responders showed significantly higher fractional anisotropy values in the same areas.

CONCLUSIONS

The results of the present study suggest that white matter tracts in the right dorsolateral prefrontal cortex and the right frontal pole may underlie dysfunctional impulse control and could be potential predictive markers for short-term treatment in patients with first-episode schizophrenia.

Increased Homotopic Connectivity in the Prefrontal Cortex Modulated by Olanzapine Predicts Therapeutic Efficacy in Patients with Schizophrenia

Background

Previous studies have revealed the abnormalities in homotopic connectivity in schizophrenia. However, the relationship of these deficits to antipsychotic treatment in schizophrenia remains unclear. This study explored the effects of antipsychotic therapy on brain homotopic connectivity and whether the homotopic connectivity of these regions might predict individual treatment response in schizophrenic patients.

Methods

A total of 21 schizophrenic patients and 20 healthy controls were scanned by the resting-state functional magnetic resonance imaging. The patients received olanzapine treatment and were scanned at two time points. Voxel-mirrored homotopic connectivity (VMHC) and pattern classification techniques were applied to analyze the imaging data.

Results

Schizophrenic patients presented significantly decreased VMHC in the temporal and inferior frontal gyri, medial prefrontal cortex (MPFC), and motor and low-level sensory processing regions (including the fusiform gyrus and cerebellum lobule VI) relative to healthy controls. The VMHC in the superior/middle MPFC was significantly increased in the patients after eight weeks of treatment. Support vector regression (SVR) analyses revealed that VMHC in the superior/middle MPFC at baseline can predict the symptomatic improvement of the positive and negative syndrome scale after eight weeks of treatment.

Conclusions

This study demonstrated that olanzapine treatment may normalize decreased homotopic connectivity in the superior/middle MPFC in schizophrenic patients. The VMHC in the superior/middle MPFC may predict individual response for antipsychotic therapy. The findings of this study conduce to the comprehension of the therapy effects of antipsychotic medications on homotopic connectivity in schizophrenia.

The neural and molecular basis of working memory function in psychosis: a multimodal PET-fMRI study

Working memory (WM) deficits predict clinical and functional outcomes in schizophrenia but are poorly understood and unaddressed by existing treatments. WM encoding and WM retrieval have not been investigated in schizophrenia without the confounds of illness chronicity or the use of antipsychotics and illicit substances. Moreover, it is unclear if WM deficits may be linked to cannabinoid 1 receptor dysfunction in schizophrenia. Sixty-six volunteers (35 controls, 31 drug-free patients with diagnoses of schizophrenia or schizoaffective disorder) completed the Sternberg Item-Recognition paradigm during an fMRI scan. Neural activation during WM encoding and WM retrieval was indexed using the blood-oxygen-level-dependent hemodynamic response. A subset of volunteers (20 controls, 20 drug-free patients) underwent a dynamic PET scan to measure [11C] MePPEP distribution volume (ml/cm3) to index CB1R availability. In a whole-brain analysis, there was a significant main effect of group on task-related BOLD responses in the superior parietal lobule during WM encoding, and the bilateral hippocampus during WM retrieval. Region of interest analyses in volunteers who had PET/fMRI indicated that there was a significant main effect of group on task-related BOLD responses in the right hippocampus, left DLPFC, left ACC during encoding; and in the bilateral hippocampus, striatum, ACC and right DLPFC during retrieval. Striatal CB1R availability was positively associated with mean striatal activation during WM retrieval in male patients (R = 0.5, p = 0.02) but not male controls (R = -0.20, p = 0.53), and this was significantly different between groups, Z = -2.20, p = 0.02. Striatal CB1R may contribute to the pathophysiology of WM deficits in male patients and have implications for drug development in schizophrenia.

Towards a framework to develop neuroimaging biomarkers of relapse in schizophrenia

Schizophrenia is a chronic disorder that often requires long-term relapse-prevention treatment. This treatment is effective for most individuals, yet approximately 20-30 % of them may still relapse despite confirmed adherence. Alternatively, for about 15 % it may be safe to discontinue medications over the long term, but since there are no means to identify who those individuals will be, the recommendation is that all individuals receive long-term relapse-prevention treatment with antipsychotic maintenance. Thus, the current approach to prevent relapse in schizophrenia may be suboptimal for over one third of individuals, either by being insufficient to protect against relapse, or by unnecessarily exposing them to medication side effects. There is great need to identify biomarkers of relapse in schizophrenia to stratify treatment according to the risk and develop therapeutics targeting its pathophysiology. In order to develop a line of research that meets those needs, it is necessary to create a framework by identifying the challenges to this type of study as well as potential areas for biomarker identification and development. In this manuscript we review the literature to create such a framework.

The Effects of Antipsychotic Treatment on the Brain of Patients With First-Episode Schizophrenia: A Selective Review of Longitudinal MRI Studies

A large number of neuroimaging studies have detected brain abnormalities in first-episode schizophrenia both before and after treatment, but it remains unclear how these abnormalities reflect the effects of antipsychotic treatment on the brain. To summarize the findings in this regard and provide potential directions for future work, we reviewed longitudinal structural and functional imaging studies in patients with first-episode schizophrenia before and after antipsychotic treatment. A total of 36 neuroimaging studies was included, involving 21 structural imaging studies and 15 functional imaging studies. Both anatomical and functional brain changes in patients after treatment were consistently observed in the frontal and temporal lobes, basal ganglia, limbic system and several key components within the default mode network (DMN). Alterations in these regions were affected by factors such as antipsychotic type, course of treatment, and duration of untreated psychosis (DUP). Over all we showed that: (a) The striatum and DMN were core target regions of treatment in schizophrenia, and their changes were related to different antipsychotics; (b) The gray matter of frontal and temporal lobes tended to reduce after long-term treatment; and (c) Longer DUP was accompanied with faster hippocampal atrophy after initial treatment, which was also associated with poorer outcome. These findings are in accordance with previous notions but should be interpreted with caution. Future studies are needed to clarify the effects of different antipsychotics in multiple conditions and to identify imaging or other biomarkers that may predict antipsychotic treatment response. With such progress, it may help choose effective pharmacological interventional strategies for individuals experiencing recent-onset schizophrenia.

Precuneus and insular hypoactivation during cognitive processing in first-episode psychosis: Systematic review and meta-analysis of fMRI studies

INTRODUCTION

The neural correlates of the cognitive dysfunction in first-episode psychosis (FEP) are still unclear. The present review and meta-analysis provide an update of the location of the abnormalities in the fMRI-measured brain response to cognitive processes in individuals with FEP.

METHODS

Systematic review and voxel-based meta-analysis of cross-sectional fMRI studies comparing neural responses to cognitive tasks between individuals with FEP and healthy controls (HC) according to PRISMA guidelines.

RESULTS

Twenty-six studies were included, comprising 598 individuals with FEP and 567 HC. Individual studies reported statistically significant hypoactivation in the dorsolateral prefrontal cortex (6 studies), frontal lobe (8 studies), cingulate (6 studies) and insula (5 studies). The meta-analysis showed statistically significant hypoactivation in the left anterior insula, precuneus and bilateral striatum.

CONCLUSIONS

While the studies tend to highlight frontal hypoactivation during cognitive tasks in FEP, our meta-analytic results show that the left precuneus and insula primarily display aberrant activation in FEP that may be associated with salience attribution to external stimuli and related to deficits in perception and regulation.

Advancing study of cognitive impairments for antipsychotic-naïve psychosis comparing high-income versus low- and middle-income countries with a focus on urban China: Systematic review of cognition and study methodology

BACKGROUND

Comparing the course of antipsychotic-naïve psychosis in low- and middle-income countries (LMIC) may help to illuminate core pathophysiologies associated with this condition. Previous reviews-primarily from high-income countries (HIC)-identified cognitive deficits in antipsychotic-naïve, first-episode psychosis, but did not examine whether individuals with psychosis with longer duration of untreated psychosis (DUP > 5 years) were included, nor whether LMIC were broadly represented.

METHOD

A comprehensive search of PUBMED from January 2002-August 2018 identified 36 studies that compared cognitive functioning in antipsychotic-naïve individuals with psychosis (IWP) and healthy controls, 20 from HIC and 16 from LMIC.

RESULTS

A key gap was identified in that LMIC study samples were primarily shorter DUP (<5 years) and were primarily conducted in urban China. Most studies matched cases and controls for age and gender but only 9 (24%) had sufficient statistical power for cognitive comparisons. Compared with healthy controls, performance of antipsychotic-naïve IWP was significantly worse in 81.3% (230/283) of different tests of cognitive domains assessed (90.1% in LMIC [118/131] and 73.7% [112/152] in HIC).

CONCLUSIONS

Most LMIC studies of cognition in antipsychotic-naïve IWP adopted standardized procedures and, like HIC studies, found broad-based impairments in cognitive functioning. However, these LMIC studies were often underpowered and primarily included samples typical of HIC: primarily male, young-adult, high-school educated IWP, in their first episode of illness with relatively short DUP (<5 years). To enhance understanding of the long-term natural course of cognitive impairments in untreated psychosis, future studies from LMIC should recruit community-dwelling IWP from rural areas where DUP may be longer.

Brain function during stages of working memory in schizophrenia and psychotic bipolar disorder

Working memory (WM) is impaired in psychotic disorders and linked to functional outcome. Most neurobiological models emphasize prefrontal cortex (PFC) dysfunction in the etiology of WM impairment. However, WM is composed of multiple processes, including encoding and maintenance, and the delineation of the neurobiology of these sub-processes has not been well characterized in schizophrenia and psychotic bipolar disorder. Functional MRI was obtained during an event-related spatial delayed match-to-sample task from 58 healthy individuals, 72 individuals with schizophrenia and 41 people with bipolar I disorder with psychotic features in order to: 1) characterize neural responses during encoding, maintenance and retrieval stages of WM using complementary region-of-interest and whole brain approaches; 2) determine whether schizophrenia and psychotic bipolar disorder exhibit similar abnormalities in WM-related brain function; and 3) elucidate the associations between WM-related brain function, task performance, and neuropsychological functioning. Both schizophrenia and psychotic bipolar disorder groups showed encoding- and maintenance-related impairments in the posterior parietal cortex (PPC) and frontal eye fields (FEF). BOLD response in the PPC and FEF, during encoding and maintenance respectively, was associated with task performance independent of group. Additionally, encoding-related activation in the PPC correlated with general neuropsychological functioning independent of group. Only encoding-related activation in the right ventral striatum differed between schizophrenia and psychotic bipolar disorder; individuals with schizophrenia showed significantly lower activation than both psychotic bipolar disorder and healthy groups. Our results are consistent with emerging evidence implicating PPC dysfunction in WM impairment and suggest interventions targeting neural activation in PPC may improve WM and neuropsychological functioning across psychotic disorders.

Baseline Frontoparietal Task-Related BOLD Activity as a Predictor of Improvement in Clinical Symptoms at 1-Year Follow-Up in Recent-Onset Psychosis

OBJECTIVE

The early course of illness in psychotic disorders is highly variable, and predictive biomarkers of treatment response have been lacking. Trial and error remains the basis for care in early psychosis, and poor outcomes are common. Early prediction of nonimprovement in response to treatment could help identify those who would benefit from alternative and/or supplemental interventions. The goal of this study was to evaluate the ability of functional MRI (fMRI) measures of cognitive control-related brain circuitry collected at baseline to predict symptomatic response in patients after 1 year.

METHODS

Patients with recent-onset (<2 years) psychotic disorders (N=82) in early psychosis specialty care were classified as improvers (>20% improvement in total score on the Brief Psychiatric Rating Scale [BPRS] at 1-year follow-up compared with baseline) or as nonimprovers. Behavioral (d' context) and fMRI (proactive control-associated activation in a priori frontoparietal regions of interest) measures of cognitive control were then evaluated on their ability to predict BPRS improvement using linear and logistic regression.

RESULTS

Cognitive control-associated measures significantly predicted BPRS improvement and improver status, with 70% positive predictive value, 60% negative predictive value, and 66% accuracy. Only the fMRI-based measure (and not the behavioral measure) significantly predicted status.

CONCLUSIONS

These results suggest that frontoparietal activation during cognitive control performance at baseline significantly predicts subsequent symptomatic improvement during early psychosis specialty care. Potential implications for fMRI-based personalized patient treatment are discussed.

Treatment effects of olanzapine on homotopic connectivity in drug-free schizophrenia at rest

OBJECTIVES

Deficits in homotopic connectivity have been implicated in schizophrenia. However, alterations in homotopic connectivity associated with antipsychotic treatments in schizophrenia remain unclear due to lack of longitudinal studies.

METHODS

Seventeen drug-free patients with recurrent schizophrenia and 24 healthy controls underwent resting-state functional magnetic resonance imaging scans. The patients were scanned at three time points (baseline, at 6 weeks of treatment, and at 6 months of treatment). Voxel-mirrored homotopic connectivity (VMHC) was applied to analyse the imaging data to examine alterations in VMHC associated with antipsychotic treatment.

RESULTS

The results showed that patients with schizophrenia exhibited decreased VMHC in the default-mode network (such as the precuneus and inferior parietal lobule) and the motor and sensory processing regions (such as the lingual gyrus, fusiform gyrus and cerebellum lobule VI), which could be normalised or denormalised by olanzapine treatment. In addition, negative correlations were found between decreased VMHC and symptom severity in the patients at baseline.

CONCLUSIONS

The present study shows that olanzapine treatment can normalise or denormalise decreased homotopic connectivity in schizophrenia. The findings also provide a new perspective to understand treatment effects of antipsychotic drugs on homotopic connectivity in schizophrenia that contribute to the disconnection hypothesis of this disease.

Frontal lobe functioning during a simple response conflict task in first-episode psychosis and its relationship to treatment response

Prior functional magnetic resonance imaging (fMRI) studies have investigated the neural mechanisms underlying cognitive control in patients with psychosis with findings of both hypo- and hyperfrontality. One factor that may contribute to inconsistent findings is the use of complex and polyfactorial tasks to investigate frontal lobe functioning. In the current study we employed a simple response conflict task during fMRI to examine differences in brain activation between patients experiencing their first-episode of psychosis (n = 33) and age- and sex-matched healthy volunteers (n = 33). We further investigated whether baseline brain activation among patients predicted changes in symptom severity and treatment response following 12 weeks of controlled antipsychotic treatment. During the task subjects were instructed to press a response button on the same side or opposite side of a circle that appeared on either side of a central fixation point. Imaging data revealed that for the contrast of opposite-side vs. same-side, patients showed significantly greater activation compared with healthy volunteers in the anterior cingulate cortex and intraparietal sulcus. Among patients, greater baseline anterior cingulate cortex, temporal-parietal junction, and superior temporal cortex activation predicted greater symptom reduction and therapeutic response following treatment. All findings remained significant after covarying for task performance. Intact performance on this relatively parsimonious task was associated with frontal hyperactivity suggesting the need for patients to utilize greater neural resources to achieve task performance comparable to healthy individuals. Moreover, frontal hyperactivity observed using a simple fMRI task may provide a biomarker for predicting treatment response in first-episode psychosis.

Functional neuroimaging in treatment resistant schizophrenia: A systematic review

Despite the availability of several drugs, about 30% of patients with schizophrenia still fail to respond properly to a course of appropriate antipsychotic treatment. Functional neuroimaging studies have shown widespread patterns of altered activation and functional connectivity in treatment-resistant schizophrenia (TRS). The aim of the present study was to examine the available functional magnetic resonance imaging studies investigating TRS and to identify common patterns of altered brain function that could predict the lack of response to antipsychotic treatment in this disorder. Alterations of activation and functional connectivity in fronto-temporal, cortico-striatal, default mode network and salience networks, and of their interplay, were associated with TRS. Our findings support the notion that large-scale network alterations present in schizophrenia lie in a continuum within treatment response with the most severe dysfunction in TRS. Few studies with small sample size and without adequate control group limit the generalizability of current literature. Future controlled longitudinal studies are needed to identify neuroimaging biomarkers of pharmacotherapy response to inform individual treatment selection and facilitate early clinical response.

Longitudinal studies of functional magnetic resonance imaging in first-episode psychosis: A systematic review

BACKGROUND

Little is known about changes in brain functioning after first-episode psychosis (FEP). Such knowledge is important for predicting the course of disease and adapting interventions. Functional magnetic resonance imaging has become a promising tool for exploring brain function at the time of symptom onset and at follow-up.

METHOD

A systematic review of longitudinal fMRI studies with FEP patients according to PRISMA guidelines. Resting-state and task-activated studies were considered together.

RESULTS

Eleven studies were included. These reported on a total of 236 FEP patients were evaluated by two fMRI scans and clinical assessments. Five studies found hypoactivation at baseline in prefrontal cortex areas, two studies found hypoactivation in the amygdala and hippocampus, and three others found hypoactivation in the basal ganglia. Other hypoactivated areas were the anterior cingulate cortex, thalamus and posterior cingulate cortex. Ten out of eleven studies reported (partial) normalization by increased activation after antipsychotic treatment. A minority of studies observed hyperactivation at baseline.

CONCLUSIONS

This review of longitudinal FEP samples studies reveals a pattern of predominantly hypoactivation in several brain areas at baseline that may normalize to a certain extent after treatment. The results should be interpreted with caution given the small number of studies and their methodological and clinical heterogeneity.

Reduced Brain Activity in the Right Putamen as an Early Predictor for Treatment Response in Drug-Naive, First-Episode Schizophrenia

Antipsychotic medications can have a significant effect on brain function after only several days of treatment. It is unclear whether such an acute effect can serve as an early predictor for treatment response in schizophrenia. Thirty-two patients with drug-naive, first-episode schizophrenia and 32 healthy controls underwent resting-state functional magnetic resonance imaging. Patients were treated with olanzapine and were scanned at baseline and 1 week of treatment. Healthy controls were scanned once at baseline. Symptom severity was assessed within the patient group using the Positive and Negative Syndrome Scale (PANSS) at three time points (baseline, 1 week of treatment, and 8 weeks of treatment). The fractional amplitude of low frequency fluctuation (fALFF) and support vector regression (SVR) methods were used to analyze the data. Compared with the control group, the patient group showed increased levels of fALFF in the bilateral putamen at baseline. After 1week of olanzapine treatment, the patient group showed decreased levels of fALFF in the right putamen relative to those at baseline. The SVR analysis found a significantly positive relationship between the reduction in fALFF after 1 week of treatment and the improvement in positive symptoms after 8 weeks of treatment (r = 0.431, p = 0.014). The present study provides evidence that early reduction and normalization of fALFF in the right putamen may serve as a predictor for treatment response in patients with schizophrenia.

Symptom attribution and frontal cortical thickness in first-episode schizophrenia

AIM

Misattribution of symptoms is a common feature of schizophrenia, and likely involves impairment of metacognitive function that may be mediated by the frontal cortex. We aimed to compare frontal cortical thickness in first-episode schizophrenia (FES) patients with matched controls, and investigate its relationship with the symptom attribution dimension of insight in FES patients.

METHODS

We examined frontal cortical thickness in 92 minimally treated FES patients at baseline presentation and 93 healthy controls aged 16-45 years. We examined for correlations between symptom attribution as determined by the Birchwood Insight Scale (BIS) symptom relabeling subscale score and cortical thickness of frontal regions of interest (ROIs). We then examined for an association between symptom attribution and cortical thickness using multiple regression analysis.

RESULTS

FES patients exhibited significantly reduced cortical thicknesses for a number of frontal regions, namely the left medial orbitofrontal, left superior frontal, left frontal pole, right rostral middle frontal, right lateral orbitofrontal and right superior frontal regions. Reduced cortical thickness in FES patients was associated with symptom misattribution for the left and right rostral middle frontal, left caudal anterior cingulate, right superior frontal, and left and right pars triangularis regions. Reduced left rostral middle frontal thickness and left anterior cingulate thickness remained significant on regression analysis.

CONCLUSION

Our findings suggest that frontal neuroanatomical deficits that are present early in the disease process may be critical to the pathogenesis of symptom attribution in schizophrenia.

Neuroimaging markers of antipsychotic treatment response in schizophrenia: An overview of magnetic resonance imaging studies

Antipsychotic drugs are the primary treatment for psychosis, yet individual response to their administration remains variable. At present, no biological predictors of response exist to guide clinicians as they select treatments for patients, and our understanding of the neurobiology underlying the heterogeneity of outcomes remains limited. Magnetic Resonance Imaging (MRI) has been applied by numerous studies to examine the response to antipsychotic treatment, though a large gap remains between their results and our clinical practice. To advance patient care with precision medicine approaches, prior work must be accounted for and built upon with future studies. This review provides an overview of studies that relate treatment outcome to various MRI-related measures, including structural, spectroscopic, diffusion tensor, and functional imaging. Knowledge derived from these studies will be discussed along with future directions for the field.

Task and resting-state fMRI studies in first-episode schizophrenia: A systematic review

In the last two decades there has been an increase on task and resting-state functional Magnetic Resonance Imaging (fMRI) studies that explore the brain's functional changes in schizophrenia. However, it remains unclear as to whether the brain's functional changes during the resting state are sensitive to the same brain regions during task fMRI. Therefore, we conducted a systematic literature search of task and resting-state fMRI studies that investigated brain pathological changes in first-episode schizophrenia (Fleischhacker et al.). Nineteen studies met the inclusion criteria; seven were resting state fMRI studies with 371 FES patients and 363 healthy controls and twelve were task fMRI studies with 235 FES patients and 291 healthy controls. We found overlapping task and resting-state fMRI abnormalities in the prefrontal regions, including the dorsal lateral prefrontal cortex, the orbital frontal cortex and the temporal lobe, especially in the left superior temporal gyrus (STG). The findings of this systematic review support the frontotemporal hypothesis of schizophrenia, and the disruption in prefrontal and STG might represent the pathophysiology of schizophrenia disorder at a relatively early stage.

Olanzapine modulates the default-mode network homogeneity in recurrent drug-free schizophrenia at rest

BACKGROUND

Previous studies on brain function alterations associated with antipsychotic treatment for schizophrenia have produced conflicting results because they used short treatment periods and different designs.

METHODS

Resting-state functional magnetic resonance imaging scans were obtained from 17 drug-free patients with recurrent schizophrenia and 24 healthy controls. The patients were treated with olanzapine for 6 months and were scanned at three time points (baseline, 6 weeks of treatment and 6 months of treatment). Network homogeneity was used to analyze the imaging data to examine default-mode network homogeneity alterations associated with antipsychotic treatment.

RESULTS

Compared with the controls, the patients at baseline showed increased network homogeneity in the bilateral precuneus and decreased network homogeneity in the bilateral middle temporal gyrus. Network homogeneity values in the bilateral precuneus decreased, and network homogeneity values in the left superior medial prefrontal cortex and the right middle temporal gyrus increased in patients administered olanzapine as antipsychotic treatment. By contrast, network homogeneity values in the left middle temporal gyrus remained unchanged in patients after treatment.

CONCLUSION

This study provides evidence that antipsychotic treatment with olanzapine modulates the default-mode network homogeneity in schizophrenia. These findings contribute to the understanding of antipsychotic treatment effects on brain functions.

Changes in White Matter Organization in Adolescent Offspring of Schizophrenia Patients

Schizophrenia is associated with frontostriatal network impairments underlying clinical and cognitive symptoms. We previously found disruptions in anatomical pathways, including the tract connecting the left nucleus accumbens and left dorsolateral prefrontal cortex (DLPFC). Similar deficits are observed in unaffected siblings of schizophrenia patients, indicating that these deficits are linked to a genetic vulnerability for the disorder. Frontostriatal tract disruptions may arise during adolescence, preceding the clinical manifestation of the disorder. However, to date, no studies have been performed to investigate frontostriatal tract connections in adolescents who are at increased familial risk for schizophrenia. In this study, we investigate the impact of familial risk on frontostriatal tract connections using diffusion tensor imaging in 27 adolescent offspring of schizophrenia patients and 32 matched control adolescents, aged 10-18 years. Mean fractional anisotropy (FA) was calculated for the tracts connecting the striatum (caudate nucleus, putamen, nucleus accumbens) and frontal cortex regions (DLPFC, medial orbital frontal cortex, inferior frontal gyrus). As expected, based on siblings data, we found an impact of familial risk on frontostriatal development: schizophrenia offspring showed increased FA in the tracts connecting nucleus accumbens and DLPFC as compared with control adolescents. Moreover, while FA increased across age in control adolescents, it did not in schizophrenia offspring. We did not find differences in FA in other frontostriatal tracts. These results indicate altered development of white matter in subjects who are at familial risk for schizophrenia and may precede frontostriatal white matter alterations in adult schizophrenia patients and siblings.

Olanzapine modulation of long- and short-range functional connectivity in the resting brain in a sample of patients with schizophrenia

Treatment effects of antipsychotic drugs on cerebral function are seldom examined. Exploring functional connectivity (FC) in drug-free schizophrenia patients before and after antipsychotic treatment can improve the understanding of antipsychotic drug mechanisms. A total of 17 drug-free patients with recurrent schizophrenia and 24 healthy controls underwent resting-state functional magnetic resonance imaging scans. Long- and short-range FC strengths (FCS) were calculated for each participant. Compared with the controls, the patients at baseline exhibited increased long-range positive FCS (lpFCS) in the bilateral inferior parietal lobule (IPL) and decreased lpFCS in the brain regions of the default-mode network (DMN) regions and sensorimotor circuits of the brain. By contrast, increased short-range positive FCS was observed in the right IPL of the patients at baseline compared with the controls. After treatment with olanzapine, increased FC in the DMN and sensorimotor circuits of the brain was noted, whereas decreased FC was observed in the left superior temporal gyrus (STG). Moreover, the alterations of the FCS values and the reductions in symptom severity among the patients after treatment were correlated. The present study provides evidence that olanzapine normalizes the abnormalities of long- and short-range FCs in schizophrenia. FC reductions in the right IPL may be associated with early treatment response, whereas those in the left STG may be related to poor treatment outcome.

Converging effects of diverse treatment modalities on frontal cortex in schizophrenia: A review of longitudinal functional magnetic resonance imaging studies

OBJECTIVES

A variety of treatment options exist for schizophrenia, but the effects of these treatments on brain function are not clearly understood. To facilitate the development of more effective treatment strategies, it is important to identify how brain function in schizophrenia patients is affected by the diverse therapeutic approaches that are currently available. The aim of the present article is to systematically review the evidence for functional brain changes associated with different treatment modalities for schizophrenia.

METHODS

We searched PubMed for longitudinal functional MRI (fMRI) studies reporting on the effects of antipsychotic medications (APM), repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), cognitive remediation therapy (CRT) and cognitive behavioral therapy for psychosis (CBTp) on brain function in schizophrenia.

RESULTS

Thirty six studies fulfilled the inclusion criteria. Functional alterations were observed in diverse brain regions. Across intervention modalities, changes in fMRI parameters were reported most commonly in frontal brain regions including prefrontal cortex, anterior cingulate and inferior frontal cortex.

CONCLUSIONS

We conclude that current treatments for schizophrenia commonly induce functional brain alterations in frontal brain regions. However, interpretability is limited by inconsistency in task and region of interest selection, and failures to replicate. Further task independent fMRI studies examining treatment effects with whole brain analysis are needed to deepen our insights.

Risperidone-induced topological alterations of anatomical brain network in first-episode drug-naive schizophrenia patients: a longitudinal diffusion tensor imaging study

BACKGROUND

It remains unclear whether the topological deficits of the white matter network documented in cross-sectional studies of chronic schizophrenia patients are due to chronic illness or to other factors such as antipsychotic treatment effects. To answer this question, we evaluated the white matter network in medication-naive first-episode schizophrenia patients (FESP) before and after a course of treatment.

METHOD

We performed a longitudinal diffusion tensor imaging study in 42 drug-naive FESP at baseline and then after 8 weeks of risperidone monotherapy, and compared them with 38 healthy volunteers. Graph theory was utilized to calculate the topological characteristics of brain anatomical network. Patients' clinical state was evaluated using the Positive and Negative Syndrome Scale (PANSS) before and after treatment.

RESULTS

Pretreatment, patients had relatively intact overall topological organizations, and deficient nodal topological properties primarily in prefrontal gyrus and limbic system components such as the bilateral anterior and posterior cingulate. Treatment with risperidone normalized topological parameters in the limbic system, and the enhancement positively correlated with the reduction in PANSS-positive symptoms. Prefrontal topological impairments persisted following treatment and negative symptoms did not improve.

CONCLUSIONS

During the early phase of antipsychotic medication treatment there are region-specific alterations in white matter topological measures. Limbic white matter topological dysfunction improves with positive symptom reduction. Prefrontal deficits and negative symptoms are unresponsive to medication intervention, and prefrontal deficits are potential trait biomarkers and targets for negative symptom treatment development.

Brain Functional Effects of Psychopharmacological Treatments in Schizophrenia: A Network-based Functional Perspective Beyond Neurotransmitter Systems

Psychopharmacological treatments for schizophrenia have always been a matter of debate and a very important issue in public health given the chronic, relapsing and disabling nature of the disorder. A thorough understanding of the pros and cons of currently available pharmacological treatments for schizophrenia is critical to better capture the features of treatment-refractory clinical pictures and plan the developing of new treatment strategies. This review focuses on brain functional changes induced by antipsychotic drugs as assessed by modern functional neuroimaging techniques (i.e. fMRI, PET, SPECT, MRI spectroscopy). The most important papers on this topic are reviewed in order to draw an ideal map of the main functional changes occurring in the brain during antipsychotic treatment. This supports the hypothesis that a network-based perspective and a functional connectivity approach are needed to fill the currently existing gap of knowledge in the field of psychotropic drugs and their mechanisms of action beyond neurotransmitter systems.

Neonatal Prefrontal Inactivation Results in Reversed Dopaminergic Responses in the Shell Subregion of the Nucleus Accumbens to NMDA Antagonists

Striatal dopaminergic dysregulation in schizophrenia could result from a prefronto-striatal dysconnectivity, of neurodevelopmental origin, involving N-methyl-d-aspartate (NMDA) receptors. The dorsomedian shell part of the nucleus accumbens is a striatal subregion of particular interest inasmuch as it has been described as the common target region for antipsychotics. Moreover, NMDA receptors located on the dopaminergic endings have been reported in the shell. The present study examines in adult rats the effects of early functional inactivation of the left prefrontal cortex on behavioral and dopaminergic responses in the dorsomedian shell part of the nucleus accumbens following administration of two noncompetitive NMDA receptor antagonists, ketamine, and dizocilpine (MK-801). The results showed that postnatal blockade of the prefrontal cortex led to increased locomotor activity as well as increased extracellular dopamine levels in the dorsomedian shell following administration of both noncompetitive NMDA receptor antagonists, and, more markedly, after treatment with the more specific one, MK-801, whereas decreased dopaminergic levels were observed in respective controls. These data suggest a link between NMDA receptor dysfunctioning and dopamine dysregulation at the level of the dorsomedian shell part of the nucleus accumbens. They may help to understand the pathophysiology of schizophrenia in a neurodevelopmental perspective.

Connectome organization is related to longitudinal changes in general functioning, symptoms and IQ in chronic schizophrenia

Emerging evidence suggests schizophrenia to involve widespread alterations in the macroscale wiring architecture of the human connectome. Recent findings of attenuated connectome alterations in unaffected siblings of schizophrenia patients suggest that altered connectome organization may relate to the vulnerability to develop the disorder, but whether it relates to progression of illness after disease onset is currently unknown. Here, we examined the interaction between connectome structure and longitudinal changes in general functioning, clinical symptoms and IQ in the 3years following MRI assessment in a group of chronically ill schizophrenia patients. Effects in patients were compared to associations between connectome organization and changes in subclinical symptoms and IQ in healthy controls and unaffected siblings of schizophrenia patients. Analyzing the patient sample revealed a relationship between structural connectivity-particularly among central 'brain hubs'-and progressive changes in general functioning (p=0.007), suggesting that more prominent impairments of hub connectivity may herald future functional decline. Our findings further indicate that affected local connectome organization relates to longitudinal increases in overall PANSS symptoms (p=0.013) and decreases in total IQ (p=0.003), independent of baseline symptoms and IQ. No significant associations were observed in controls and siblings, suggesting that the findings in patients represent effects of ongoing illness, as opposed to normal time-related changes. In all, our findings suggest connectome structure to have predictive value for the course of illness in schizophrenia.

Catecholaminergic neuronal network dysfunction in the frontal lobe of a genetic mouse model of schizophrenia

BACKGROUND

The precise aetiology of schizophrenia remains unclear. The neurodevelopmental hypothesis of schizophrenia has been proposed based on the accumulation of genomic or neuroimaging studies.

OBJECTIVE

In this study, we examined the catecholaminergic neuronal networks in the frontal cortices of disrupted-in-schizophrenia 1 (DISC1) knockout (KO) mice, which are considered to be a useful model of schizophrenia.

METHODS

Six DISC1 homozygous KO mice and six age-matched littermates were used. The animals' brains were cut into 20-μm-thick slices, which were then immunohistochemically stained using an anti-tyrosine hydroxylase (TH) monoclonal antibody.

RESULTS

The TH-immunopositive fibres detected in the orbitofrontal cortices of the DISC1 KO mice were significantly shorter than those seen in the wild-type mice.

CONCLUSION

These neuropathological findings indicate that the hypofrontal symptoms of schizophrenia are associated with higher mental function deficiencies or cognitive dysfunction such as a loss of working memory.

White-matter connectivity related to paliperidone treatment response in patients with schizophrenia

The objective of this study was to examine whether white-matter (WM) connectivity of patients with schizophrenia at early stage of treatment is related to treatment response after paliperidone extended-release (ER) treatment. Forty-one patients with schizophrenia and 17 age- and sex-matched healthy control subjects were included in this study. Brain magnetic resonance scans at 3 Tesla were conducted at early stage of treatment. Voxel-wise statistical analysis of the fractional anisotropy (FA) data was performed using Tract-Based Spatial Statistics. At baseline and eight weeks after paliperidone treatment, patients were assessed using the Positive and Negative Syndrome Scale, the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. Among the patients with schizophrenia, the FA values of the corpus callosum, corona radiata, internal capsule, external capsule, superior longitudinal fasciculus and fronto-temporal WM regions showed significant negative correlations with scores of the treatment response. The current study suggests that the treatment response after paliperidone ER treatment may be associated with the fronto-temporo-limbic WM connectivity at early stage of treatment in patients with schizophrenia, and it could be used as a predictor of treatment response to paliperidone ER treatment after studies with large samples verify these results.

Impaired frontal processing during agency inferences in schizophrenia

People generally experience themselves as the cause of outcomes following from their own actions. Such agency inferences occur fluently and are essential to social interaction. However, schizophrenia patients often experience difficulties in distinguishing their own actions from those of others. Building on recent research into the neural substrates underlying agency inferences in healthy individuals, the present study investigates how these inferences are represented on a neural level in patients with schizophrenia. Thirty-one schizophrenia patients and 31 healthy controls performed an agency inference task while functional magnetic resonance images were obtained. Participants were presented with a task wherein the relationship between their actions and the subsequent outcomes was ambiguous. They received instructions to cause specific outcomes to occur by pressing a key, but the task was designed to match or mismatch the color outcome with the participants' goal. Both groups experienced stronger agency when their goal matched (vs. mismatched) the outcome. However, region of interest analyses revealed that only controls showed the expected involvement of the medial prefrontal cortex and superior frontal gyrus, whereas in patients the agency experience was not related to brain activation. These findings are discussed in light of a hypofrontality model of schizophrenia.

Diminishing striatal activation across adolescent development during reward anticipation in offspring of schizophrenia patients

Schizophrenia is a severe psychiatric disorder associated with impaired fronto-striatal functioning. Similar deficits are observed in unaffected siblings of patients, indicating that these deficits are linked to a familial risk for the disorder. Fronto-striatal deficits may arise during adolescence and precede clinical manifestation of the disorder. However, the development of the fronto-striatal network in adolescents at increased familial risk for schizophrenia is still poorly understood. In this cross-sectional study, we investigate the impact of familial risk on fronto-striatal functioning across age related to reward anticipation and receipt in 25 adolescent offspring of schizophrenia patients (SZ offspring) and 36 age-matched healthy controls (range 10-19years). Subjects performed a reward task while being scanned with functional MRI. Overall response times and the amount of money won did not differ between the groups. Striatal activation during reward anticipation decreased across age in the SZ offspring, while it did not in the healthy controls. Activation in the orbitofrontal cortex during reward receipt did not differ between the groups. These results, taken together with data from adult schizophrenia patients and their siblings, indicate that the diminishing striatal activation across adolescence may signify a familial vulnerability for schizophrenia.

Reduced fronto-striatal white matter integrity in schizophrenia patients and unaffected siblings: a DTI study

Background:

Schizophrenia is characterized by impairments in the fronto–striatal network. Underlying these impairments may be disruptions in anatomical pathways connecting frontal and striatal regions. However, the specifics of these disruptions remain unclear and whether these impairments are related to the genetic vulnerability of schizophrenia is not known.

Methods:

Here, we investigated fronto–striatal tract connections in 24 schizophrenia patients, 30 unaffected siblings, and 58 healthy controls using diffusion tensor imaging. Mean fractional anisotropy (FA) was calculated for tracts connecting the striatum with frontal cortex regions including the dorsolateral prefrontal cortex (DLPFC), medial orbital frontal cortex, and inferior frontal gyrus. Specifically, the striatum was divided into three subregions (caudate nucleus, putamen, and nucleus accumbens) and mean FA was computed for tracts originating from these striatal subregions.

Results:

We found no differences between patients, siblings, and controls in mean FA when taking the whole striatum as a seed region. However, subregion analyses showed reduced FA in the tract connecting the left nucleus accumbens and left DLPFC in both patients (P=0.0003) and siblings (P=0.0008) compared with controls.

Conclusions:

The result of reduced FA in the tract connecting the left nucleus accumbens and left DLPFC indicates a possible reduction of white matter integrity, commonly associated with schizophrenia. As both patients and unaffected siblings show reduced FA, this may represent a vulnerability factor for schizophrenia.

Increased orbitofrontal cortex activation associated with "pro-obsessive" antipsychotic treatment in patients with schizophrenia

BACKGROUND

Patients with schizophrenia have an approximately 10-fold higher risk for obsessive-compulsive symptoms (OCS) than the general population. A large subgroup seems to experience OCS as a consequence of second-generation antipsychotic agents (SGA), such as clozapine. So far little is known about underlying neural mechanisms.

METHODS

To investigate the role of SGA treatment on neural processing related to OCS in patients with schizophrenia, we stratified patients according to their monotherapy into 2 groups (group I: clozapine or olanzapine; group II: amisulpride or aripiprazole). We used an fMRI approach, applying a go/no-go task assessing inhibitory control and an n-back task measuring working memory.

RESULTS

We enrolled 21 patients in group I and 19 patients in group II. Groups did not differ regarding age, sex, education or severity of psychotic symptoms. Frequency and severity of OCS were significantly higher in group I and were associated with pronounced deficits in specific cognitive abilities. Whereas brain activation patterns did not differ during working memory, group I showed significantly increased activation in the orbitofrontal cortex (OFC) during response inhibition. Alterations in OFC activation were associated with the severity of obsessions and mediated the association between SGA treatment and co-occurring OCS on a trend level.

LIMITATIONS

The main limitation of this study is its cross-sectional design.

CONCLUSION

To our knowledge, this is the first imaging study conducted to elucidate SGA effects on neural systems related to OCS. We propose that alterations in brain functioning reflect a pathogenic mechanism in the development of SGA-induced OCS in patients with schizophrenia. Longitudinal studies and randomized interventions are needed to prove the suggested causal interrelations.

Fronto-striatal dysfunction during reward processing in unaffected siblings of schizophrenia patients

Schizophrenia is a psychiatric disorder that is associated with impaired functioning of the fronto-striatal network, in particular during reward processing. However, it is unclear whether this dysfunction is related to the illness itself or whether it reflects a genetic vulnerability to develop schizophrenia. Here, we examined reward processing in unaffected siblings of schizophrenia patients using functional magnetic resonance imaging. Brain activity was measured during reward anticipation and reward outcome in 27 unaffected siblings of schizophrenia patients and 29 healthy volunteers using a modified monetary incentive delay task. Task performance was manipulated online so that all subjects won the same amount of money. Despite equal performance, siblings showed reduced activation in the ventral striatum, insula, and supplementary motor area (SMA) during reward anticipation compared to controls. Decreased ventral striatal activation in siblings was correlated with sub-clinical negative symptoms. During the outcome of reward, siblings showed increased activation in the ventral striatum and orbitofrontal cortex compared to controls. Our finding of decreased activity in the ventral striatum during reward anticipation and increased activity in this region during receiving reward may indicate impaired cue processing in siblings. This is consistent with the notion of dopamine dysfunction typically associated with schizophrenia. Since unaffected siblings share on average 50% of their genes with their ill relatives, these deficits may be related to the genetic vulnerability for schizophrenia.

Meta-analysis of cognitive performance in drug-naïve patients with schizophrenia

Cognitive deficits represent a significant characteristic of schizophrenia. However, a majority of the clinical studies have been conducted in antipsychotic drug treated patients. Thus, it remains unclear if significant cognitive impairments exist in the absence of medication. This is the first meta-analysis of cognitive findings in drug-naïve patients with schizophrenia. Cognitive data from 23 studies encompassing 1106 patients and 1385 controls published from 1992 to 2013 were included. Tests were to a large extent ordered in cognitive domains according to the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) battery. Analysis was performed with STATA using the random-effects model and heterogeneity as well as Egger's publication bias was assessed. Overall the results show that patients performed worse than healthy controls in all cognitive domains with medium to large effect sizes. Verbal memory, speed of processing and working memory were three of the domains with the greatest impairments. The pattern of results is in line with previous meta-analytic findings in antipsychotic treated patients. The present meta-analysis confirms the existence of significant cognitive impairments at the early stage of the illness in the absence of antipsychotic medication.

Antipsychotic drug effects in schizophrenia: a review of longitudinal FMRI investigations and neural interpretations

The evidence that antipsychotics improve brain function and reduce symptoms in schizophrenia is unmistakable, but how antipsychotics change brain function is poorly understood, especially within neuronal systems. In this review, we investigated the hypothesized normalization of the functional magnetic resonance imaging (fMRI) blood oxygen level dependent signal in the context of antipsychotic treatment. First, we conducted a systematic PubMed search to identify eight fMRI investigations that met the following inclusion criteria: case-control, longitudinal design; pre- and post-treatment contrasts with a healthy comparison group; and antipsychotic-free or antipsychotic-naive patients with schizophrenia at the start of the investigation. We hypothesized that aberrant activation patterns or connectivity between patients with schizophrenia and healthy comparisons at the first imaging assessment would no longer be apparent or "normalize" at the second imaging assessment. The included studies differed by analysis method and fMRI task but demonstrated normalization of fMRI activation or connectivity during the treatment interval. Second, we reviewed putative mechanisms from animal studies that support normalization of the BOLD signal in schizophrenia. We provided several neuronal-based interpretations of these changes of the BOLD signal that may be attributable to long-term antipsychotic administration.

White matter integrity as a predictor of response to treatment in first episode psychosis

The integrity of brain white matter connections is central to a patient's ability to respond to pharmacological interventions. This study tested this hypothesis using a specific measure of white matter integrity, and examining its relationship to treatment response using a prospective design in patients within their first episode of psychosis. Diffusion tensor imaging data were acquired in 63 patients with first episode psychosis and 52 healthy control subjects (baseline). Response was assessed after 12 weeks and patients were classified as responders or non-responders according to treatment outcome. At this second time-point, they also underwent a second diffusion tensor imaging scan. Tract-based spatial statistics were used to assess fractional anisotropy as a marker of white matter integrity. At baseline, non-responders showed lower fractional anisotropy than both responders and healthy control subjects (P < 0.05; family-wise error-corrected), mainly in the uncinate, cingulum and corpus callosum, whereas responders were indistinguishable from healthy control subjects. After 12 weeks, there was an increase in fractional anisotropy in both responders and non-responders, positively correlated with antipsychotic exposure. This represents one of the largest, controlled investigations of white matter integrity and response to antipsychotic treatment early in psychosis. These data, together with earlier findings on cortical grey matter, suggest that grey and white matter integrity at the start of treatment is an important moderator of response to antipsychotics. These findings can inform patient stratification to anticipate care needs, and raise the possibility that antipsychotics may restore white matter integrity as part of the therapeutic response.

Working memory and default mode network abnormalities in unaffected siblings of schizophrenia patients

BACKGROUND

Impaired working memory (WM) is a hallmark of schizophrenia. In addition to classical WM regions such as the dorsolateral prefrontal cortex (DLPFC) and the striatum, dysfunctions in the default-mode network (DMN) contribute to these WM deficits. Unaffected siblings of patients also show WM impairments. However, the nature of the functional deficits underlying these impairments is unclear, mainly because of impaired performance confounding neuroimaging results.

METHODS

Here, we investigated WM and DMN activity in 23 unaffected siblings of schizophrenia patients and 24 healthy volunteers using fMRI and a Sternberg WM task. WM load was determined prior to scanning to ensure 90% accuracy for all subjects.

RESULTS

Siblings showed hyperactivation during the encoding phase of WM in the right medial prefrontal cortex (MPFC) which is the anterior part of the DMN. No differences were found during the maintenance phase. During the retrieval phase, siblings showed hyperactivation in WM regions: DLPFC, inferior parietal cortex and the striatum. Siblings who showed hyperactivity in the MPFC during encoding showed DLPFC and striatum hyperactivation during retrieval.

CONCLUSIONS

Our finding of hyperactivation in WM and DMN areas indicates that siblings fail to adequately inhibit DMN activity during demanding cognitive tasks and subsequently hyperactivate WM areas. This failure may reflect dopamine hyperactivity in the striatum which prevents adequate DMN suppression needed for effective WM. This study provides support for the notion that aberrant WM and DMN activation patterns may represent candidate endophenotypes for schizophrenia.

Neuroimaging as a potential biomarker to optimize psychiatric research and treatment

Complex, polygenic phenotypes in psychiatry hamper our understanding of the underlying molecular pathways and mechanisms of many diseases. The unknown aetiology, together with symptoms which often show a large variability both across individuals and over time and also tend to respond comparatively slowly to medication, can be a problem for patient treatment and drug development. We argue that neuroimaging has the potential to improve psychiatric treatment in two ways. First, by reducing phenotypic complexity, neuroimaging intermediate phenotypes can help to identify disease-related genes and can shed light into the biological mechanisms of known risk genes. Second, quantitative neuroimaging markers - reflecting the spectrum of impairment on a brain-based level - can be used as a more sensitive, reliable and immediate treatment response biomarker. In the end, enhancing both our understanding of the pathophysiology of psychiatric disorders and the prediction of treatment success could eventually optimise current therapy plans.

Reduced dorso-lateral prefrontal cortex in treatment resistant schizophrenia

BACKGROUND

Treatment resistance affects up to one third of patients with schizophrenia (SCZ). A better understanding of its biological underlying processes could improve treatment. The aim of this study was to compare cortical thickness between non-resistant SCZ (NR-SCZ), treatment-resistant SCZ (TR-SCZ) patients and healthy controls (HC).

METHODOLOGY

Structural MRI scans were obtained from 3 groups of individuals: 61 treatment resistant SCZ individuals, 67 non-resistant SCZ and 80 healthy controls. Images were analyzed using cortical surface modelling (implemented in freesurfer package) to identify group differences in cortical thickness. Statistical significant differences were identified using Monte-Carlo simulation method with a corrected p-cluster<0.01.

RESULTS

Patients in the TR-SCZ group showed a widespread reduction in cortical thickness in frontal, parietal, temporal and occipital regions bilaterally. NR-SCZ group had reduced cortex in two regions (left superior frontal cortex and left caudal middle frontal cortex). TR-SCZ group also showed decreased thickness in the left dorsolateral prefrontal cortex (DLPFC) when compared with patients from NR-SCZ group.

CONCLUSIONS

The reduction in cortical thickness in DLPFC indicates a more severe form of the disease or a specific finding for this group. Alterations in this region should be explored as a putative marker for treatment resistance. Prospective studies, with individuals being followed from first episode psychosis until refractoriness is diagnosed, are needed to clarify these hypotheses.

Neural markers of negative symptom outcomes in distributed working memory brain activity of antipsychotic-naive schizophrenia patients

Since working memory deficits in schizophrenia have been linked to negative symptoms, we tested whether features of the one could predict the treatment outcome in the other. Specifically, we hypothesized that working memory-related functional connectivity at pre-treatment can predict improvement of negative symptoms in antipsychotic-treated patients. Fourteen antipsychotic-naive patients with first-episode schizophrenia were clinically assessed before and after 7 months of quetiapine monotherapy. At baseline, patients underwent functional magnetic resonance imaging while performing a verbal n-back task. Spatial independent component analysis identified task-modulated brain networks. A linear support vector machine was trained with these components to discriminate six patients who showed improvement in negative symptoms from eight non-improvers. Classification accuracy and significance was estimated by leave-one-out cross-validation and permutation tests, respectively. Two frontoparietal and one default mode network components predicted negative symptom improvement with a classification accuracy of 79% (p = 0.003). Discriminating features were found in the frontoparietal networks but not the default mode network. These preliminary data suggest that functional patterns at baseline can predict negative symptom treatment-response in schizophrenia. This information may be used to stratify patients into subgroups thereby facilitating personalized treatment.

Memory deficits in schizophrenia: a selective review of functional magnetic resonance imaging (FMRI) studies

Schizophrenia is a complex chronic mental illness that is characterized by positive, negative and cognitive symptoms. Cognitive deficits are most predictive of long-term outcomes, with abnormalities in memory being the most robust finding. The advent of functional magnetic resonance imaging (fMRI) has allowed exploring neural correlates of memory deficits in vivo. In this article, we will give a selective review of fMRI studies probing brain regions and functional networks that are thought to be related to abnormal memory performance in two memory systems prominently affected in schizophrenia; working memory and episodic memory. We revisit the classic "hypofrontality" hypothesis of working memory deficits and explore evidence for frontotemporal dysconnectivity underlying episodic memory abnormalities. We conclude that fMRI studies of memory deficits in schizophrenia are far from universal. However, the current literature does suggest that alterations are not isolated to a few brain regions, but are characterized by abnormalities within large-scale brain networks.

Proton magnetic resonance spectroscopy measures related to short-term symptomatic outcome in chronic schizophrenia

INTRODUCTION

Proton magnetic resonance spectroscopy (¹H MRS) enables the evaluation of in vivo brain function. The purpose of the study was to compare ¹H MRS measurements in schizophrenic patients, who were clinical responders after short-term antipsychotic treatment, with non-responders and healthy controls.

METHODS

We investigated a group of 47 patients diagnosed with schizophrenia. Patients were examined twice--once after a period of at least 7 days without neuroleptics and the second time at least 4 weeks after therapy with stable doses of medication. The follow-up was available in 42 patients. Baseline MRS measurements of clinical responders were compared with non-responders and the group of healthy controls (N=26). We assessed the following metabolite ratios: NAA (N-acetylaspartate), Glx (complex of GABA, glutamine and glutamate), Cho (choline) and mI (myo-inositol) to creatinine (Cr) in the left frontal and temporal lobes and the thalamus.

RESULTS

Responders showed a significantly lower baseline frontal Glx/Cr level than non-responders. Both groups had a significantly lower NAA/Cr ratio in the frontal lobe than the controls, but only non-responders had a significantly lower NAA/Cr ratio in the thalamus.

CONCLUSIONS

Our results confirm the relationship between the glutamatergic system and pathophysiology of schizophrenia and suggest a significant value of ¹H MRS examination in the assessment of the future treatment effect.

Brain connectivity studies in schizophrenia: unravelling the effects of antipsychotics

Impaired brain connectivity is a hallmark of schizophrenia brain dysfunction. However, the effect of drug treatment and challenges on the dysconnectivity of functional networks in schizophrenia is an understudied area. In this review, we provide an overview of functional magnetic resonance imaging studies examining dysconnectivity in schizophrenia and discuss the few studies which have also attempted to probe connectivity changes with antipsychotic drug treatment. We conclude with a discussion of possible avenues for further investigation.

Neuroimaging schizophrenia: a picture is worth a thousand words, but is it saying anything important?

Schizophrenia is characterized by neurostructural and neurofunctional aberrations that have now been demonstrated through neuroimaging research. The article reviews recent studies that have attempted to use neuroimaging to understand the relation between neurological abnormalities and aspects of the phenomenology of schizophrenia. Neuroimaging studies show that neurostructural and neurofunctional abnormalities are present in people with schizophrenia and their close relatives and may represent putative endophenotypes. Neuroimaging phenotypes predict the emergence of psychosis in individuals classified as high-risk. Neuroimaging studies have linked structural and functional abnormalities to symptoms; and progressive structural changes to clinical course and functional outcome. Neuroimaging has successfully indexed the neurotoxic and neuroprotective effects of schizophrenia treatments. Pictures can inform about aspects of the phenomenology of schizophrenia including etiology, onset, symptoms, clinical course, and treatment effects but this assertion is tempered by the scientific and practical limitations of neuroimaging.

Can structural neuroimaging be used to define phenotypes and course of schizophrenia?

This article examines whether structural neuroimaging measures have been found to predict outcome in schizophrenia and whether changes in neuroimaging measures have been found to correlate with poor outcome in the disorder. Overall, there is little compelling evidence that structural neuroimaging measures in either first-episode or chronic patients predict future outcome. Progressive brain changes might reflect a neuroimaging phenotype associated with a worse course of the disorder. At the same time, there are many fruitful avenues that future research could take in an attempt to better predict future outcome or to identify specific imaging phenotypes associated with outcome.

Differential neuregulin 1 cleavage in the prefrontal cortex and hippocampus in schizophrenia and bipolar disorder: preliminary findings

Background

Neuregulin 1 (NRG1) is a key candidate susceptibility gene for both schizophrenia (SCZ) and bipolar disorder (BPD). The function of the NRG1 transmembrane proteins is regulated by cleavage. Alteration of membrane bound-NRG1 cleavage has been previously shown to be associated with behavioral impairments in mouse models lacking expression of NRG1-cleavage enzymes such as BACE1 and gamma secretase. We sought to determine whether alterations in NRG1 cleavage and associated enzymes occur in patients with SCZ and BPD.

Methodology/Principal Findings

Using human postmortem brain, we evaluated protein expression of NRG1 cleavage products and enzymes that cleave at the external (BACE1, ADAM17, ADAM19) and internal (PS1-gamma secretase) sides of the cell membrane. We used three different cohorts (Controls, SCZ and BPD) and two distinct brain regions: BA9-prefrontal cortex (Controls (n = 6), SCZ (n = 6) and BPD (n = 6)) and hippocampus (Controls (n = 5), SCZ (n = 6) and BPD (n = 6)). In BA9, the ratio of the NRG1 N-terminal fragment relative to full length was significantly upregulated in the SCZ cohort (Bonferroni test, p = 0.011). ADAM17 was negatively correlated with full length NRG1 levels in the SCZ cohort (r = –0.926, p = 0.008). In the hippocampus we found significantly lower levels of a soluble 50 kDa NRG1 fragment in the two affected groups compared the control cohort (Bonferroni test, p = 0.0018). We also examined the relationship of specific symptomatology criteria with measures of NRG1 cleavage using the Bipolar Inventory of Signs and Symptoms Scale (BISS) and the Montgomery Åsberg Depression Rating Scale (MADRS). Our results showed a positive correlation between ADAM19 and psychosis (r = 0.595 p = 0.019); PS1 and mania (r = 0.535, p = 0.040); PS1 and depression (r = 0.567, p = 0.027) in BA9, and BACE1 with anxiety (r = 0.608, p = 0.03) in the hippocampus.

Conclusion/Significance

Our preliminary findings suggest region-specific alterations in NRG1 cleavage in SCZ and BPD patients. These changes may be associated with specific symptoms in these psychiatric disorders.