Anatomical and functional cerebral variables associated with basal symptoms but not risperidone response in minimally treated schizophrenia

GL-II-73, a Positive Allosteric Modulator of α5GABAA Receptors, Reverses Dopamine System Dysfunction Associated with Pilocarpine-Induced Temporal Lobe Epilepsy

Although seizures are a hallmark feature of temporal lobe epilepsy (TLE), psychiatric comorbidities, including psychosis, are frequently associated with TLE and contribute to decreased quality of life. Currently, there are no defined therapeutic protocols to manage psychosis in TLE patients, as antipsychotic agents may induce epileptic seizures and are associated with severe side effects and pharmacokinetic and pharmacodynamic interactions with antiepileptic drugs. Thus, novel treatment strategies are necessary. Several lines of evidence suggest that hippocampal hyperactivity is central to the pathology of both TLE and psychosis; therefore, restoring hippocampal activity back to normal levels may be a novel therapeutic approach for treating psychosis in TLE. In rodent models, increased activity in the ventral hippocampus (vHipp) results in aberrant dopamine system function, which is thought to underlie symptoms of psychosis. Indeed, we have previously demonstrated that targeting α5-containing γ-aminobutyric acid receptors (α5GABAARs), an inhibitory receptor abundant in the hippocampus, with positive allosteric modulators (PAMs), can restore dopamine system function in rodent models displaying hippocampal hyperactivity. Thus, we posited that α5-PAMs may be beneficial in a model used to study TLE. Here, we demonstrate that pilocarpine-induced TLE is associated with increased VTA dopamine neuron activity, an effect that was completely reversed by intra-vHipp administration of GL-II-73, a selective α5-PAM. Further, pilocarpine did not alter the hippocampal α5GABAAR expression or synaptic localization that may affect the efficacy of α5-PAMs. Taken together, these results suggest augmenting α5GABAAR function as a novel therapeutic modality for the treatment of psychosis in TLE.

Glutamatergic dysfunction leads to a hyper-dopaminergic phenotype through deficits in short-term habituation: a mechanism for aberrant salience

Psychosis in disorders like schizophrenia is commonly associated with aberrant salience and elevated striatal dopamine. However, the underlying cause(s) of this hyper-dopaminergic state remain elusive. Various lines of evidence point to glutamatergic dysfunction and impairments in synaptic plasticity in the etiology of schizophrenia, including deficits associated with the GluA1 AMPAR subunit. GluA1 knockout (Gria1^-/-) mice provide a model of impaired synaptic plasticity in schizophrenia and exhibit a selective deficit in a form of short-term memory which underlies short-term habituation. As such, these mice are unable to reduce attention to recently presented stimuli. In this study we used fast-scan cyclic voltammetry to measure phasic dopamine responses in the nucleus accumbens of Gria1^-/- mice to determine whether this behavioral phenotype might be a key driver of a hyper-dopaminergic state. There was no effect of GluA1 deletion on electrically-evoked dopamine responses in anaesthetized mice, demonstrating normal endogenous release properties of dopamine neurons in Gria1^-/- mice. Furthermore, dopamine signals were initially similar in Gria1^-/- mice compared to controls in response to both sucrose rewards and neutral light stimuli. They were also equally sensitive to changes in the magnitude of delivered rewards. In contrast, however, these stimulus-evoked dopamine signals failed to habituate with repeated presentations in Gria1^-/- mice, resulting in a task-relevant, hyper-dopaminergic phenotype. Thus, here we show that GluA1 dysfunction, resulting in impaired short-term habituation, is a key driver of enhanced striatal dopamine responses, which may be an important contributor to aberrant salience and psychosis in psychiatric disorders like schizophrenia.

Hippocampal dysfunction in the pathophysiology of schizophrenia: a selective review and hypothesis for early detection and intervention

Scientists have long sought to characterize the pathophysiologic basis of schizophrenia and develop biomarkers that could identify the illness. Extensive postmortem and in vivo neuroimaging research has described the early involvement of the hippocampus in the pathophysiology of schizophrenia. In this context, we have developed a hypothesis that describes the evolution of schizophrenia-from the premorbid through the prodromal stages to syndromal psychosis-and posits dysregulation of glutamate neurotransmission beginning in the CA1 region of the hippocampus as inducing attenuated psychotic symptoms and initiating the transition to syndromal psychosis. As the illness progresses, this pathological process expands to other regions of the hippocampal circuit and projection fields in other anatomic areas including the frontal cortex, and induces an atrophic process in which hippocampal neuropil is reduced and interneurons are lost. This paper will describe the studies of our group and other investigators supporting this pathophysiological hypothesis, as well as its implications for early detection and therapeutic intervention.

Use of transcranial direct current stimulation for the treatment of auditory hallucinations of schizophrenia - a systematic review

INTRODUCTION

Auditory hallucinations are defined as experiences of auditory perceptions in the absence of a provoking external stimulus. They are the most prevalent symptoms of schizophrenia with high capacity for chronicity and refractoriness during the course of disease. The transcranial direct current stimulation (tDCS) - a safe, portable, and inexpensive neuromodulation technique - has emerged as a promising treatment for the management of auditory hallucinations.

OBJECTIVE

The aim of this study is to analyze the level of evidence in the literature available for the use of tDCS as a treatment for auditory hallucinations in schizophrenia.

METHODS

A systematic review was performed, searching in the main electronic databases including the Cochrane Library and MEDLINE/PubMed. The searches were performed by combining descriptors, applying terms of the Medical Subject Headings (MeSH) of Descriptors of Health Sciences and descriptors contractions. PRISMA protocol was used as a guide and the terms used were the clinical outcomes ("Schizophrenia" OR "Auditory Hallucinations" OR "Auditory Verbal Hallucinations" OR "Psychosis") searched together ("AND") with interventions ("transcranial Direct Current Stimulation" OR "tDCS" OR "Brain Polarization").

RESULTS

Six randomized controlled trials that evaluated the effects of tDCS on the severity of auditory hallucinations in schizophrenic patients were selected. Analysis of the clinical results of these studies pointed toward incongruence in the information with regard to the therapeutic use of tDCS with a view to reducing the severity of auditory hallucinations in schizophrenia. Only three studies revealed a therapeutic benefit, manifested by reductions in severity and frequency of auditory verbal hallucinations in schizophrenic patients.

CONCLUSION

Although tDCS has shown promising results in reducing the severity of auditory hallucinations in schizophrenic patients, this technique cannot yet be used as a therapeutic alternative due to lack of studies with large sample sizes that portray the positive effects that have been described.

Childhood neglect predicts disorganization in schizophrenia through grey matter decrease in dorsolateral prefrontal cortex

OBJECTIVE

Psychosocial trauma during childhood is associated with schizophrenia vulnerability. The pattern of grey matter decrease is similar to brain alterations seen in schizophrenia. Our objective was to explore the links between childhood trauma, brain morphology and schizophrenia symptoms.

METHOD

Twenty-one patients with schizophrenia stabilized with atypical antipsychotic monotherapy and 30 healthy control subjects completed the study. Anatomical MRI images were analysed using optimized voxel-based morphometry (VBM). Childhood trauma was assessed with the Childhood Trauma Questionnaire, and symptoms were rated on the Scale for the Assessment of Negative Symptoms (SANS) and Scale for the Assessment of Positive Symptoms (SAPS) (disorganization, positive and negative symptoms). In the schizophrenia group, we used structural equation modelling in a path analysis.

RESULTS

Total grey matter volume was negatively associated with emotional neglect (EN) in patients with schizophrenia. Whole-brain VBM analyses of grey matter in the schizophrenia group revealed a specific inversed association between EN and the right dorsolateral prefrontal cortex (DLPFC). Path analyses identified a well-fitted model in which EN predicted grey matter density in DLPFC, which in turn predicted the disorganization score.

CONCLUSION

Our findings suggest that EN during childhood could have an impact on psychopathology in schizophrenia, which would be mediated by developmental effects on brain regions such as the DLPFC.

Structural correlates of formal thought disorder in schizophrenia: An ultra-high field multivariate morphometry study

BACKGROUND

Persistent formal thought disorder (FTD) is one of the most characteristic features of schizophrenia. Several neuroimaging studies report spatially distinct neuroanatomical changes in association with FTD. Given that most studies so far have employed a univariate localisation approach that obscures the study of covarying interregional relationships, the present study focussed on the multivariate systemic pattern of anatomical changes that contribute to FTD.

METHODS

Speech samples from nineteen medicated clinically stable schizophrenia patients and 20 healthy controls were evaluated for subtle formal thought disorder. Ultra high-field (7T) anatomical Magnetic Resonance Imaging scans were obtained from all subjects. Multivariate morphometric patterns were identified using an independent component approach (source based morphometry). Using multiple regression analysis, the morphometric patterns predicting positive and negative FTD scores were identified.

RESULTS

Morphometric variations in grey matter predicted a substantial portion of inter-individual variance in negative but not positive FTD. A pattern of concomitant striato-insular/precuneus reduction along with frontocingular grey matter increase had a significant association with negative FTD.

CONCLUSIONS

These results suggest that concomitant increase and decrease in grey matter occur in association with persistent negative thought disorder in clinically stable individuals with schizophrenia.

Correlations between brain structure and symptom dimensions of psychosis in schizophrenia, schizoaffective, and psychotic bipolar I disorders

INTRODUCTION

Structural alterations may correlate with symptom severity in psychotic disorders, but the existing literature on this issue is heterogeneous. In addition, it is not known how cortical thickness and cortical surface area correlate with symptom dimensions of psychosis.

METHODS

Subjects included 455 individuals with schizophrenia, schizoaffective, or bipolar I disorders. Data were obtained as part of the Bipolar Schizophrenia Network for Intermediate Phenotypes study. Diagnosis was made through the Structured Clinical Interview for DSM-IV. Positive and negative symptom subscales were assessed using the Positive and Negative Syndrome Scale. Structural brain measurements were extracted from T1-weight structural MRIs using FreeSurfer v5.1 and were correlated with symptom subscales using partial correlations. Exploratory factor analysis was also used to identify factors among those regions correlating with symptom subscales.

RESULTS

The positive symptom subscale correlated inversely with gray matter volume (GMV) and cortical thickness in frontal and temporal regions, whereas the negative symptom subscale correlated inversely with right frontal cortical surface area. Among regions correlating with the positive subscale, factor analysis identified four factors, including a temporal cortical thickness factor and frontal GMV factor. Among regions correlating with the negative subscale, factor analysis identified a frontal GMV-cortical surface area factor. There was no significant diagnosis by structure interactions with symptom severity.

CONCLUSIONS

Structural measures correlate with positive and negative symptom severity in psychotic disorders. Cortical thickness demonstrated more associations with psychopathology than cortical surface area.

Role of the prefrontal cortex in altered hippocampal-accumbens synaptic plasticity in a developmental animal model of schizophrenia

Schizophrenia is characterized by alterations in cortico-limbic processes believed to involve modifications in activity within the prefrontal cortex (PFC) and the hippocampus. The nucleus accumbens (NAc) integrates information from these 2 brain regions and is involved in cognitive and psychomotor functions that are disrupted in schizophrenia, indicating an important role for this structure in the pathophysiology of this disorder. In this study, we used in vivo electrophysiological recordings from the NAc and the PFC of adult rats and the MAM developmental disruption rodent model of schizophrenia to explore the influence of the medial PFC on the hippocampal-accumbens pathway. We found that, in MAM-treated rats, tetanization of hippocampal inputs to the NAc produce opposite synaptic plasticity compared with controls, which is a consequence of alterations in the hippocampal-mPFC pathway. Moreover, we show that administration of the D2-receptor-blocking antipsychotic drug sulpiride either systemically or directly into the mPFC reverses the alterations in the MAM rat. Therefore, specific disruptions in cortical and hippocampal inputs in the MAM-treated rat abnormally alter plasticity in subcortical structures. Moreover, our results suggest that, in the presence of antipsychotic drugs, the disrupted plasticities are normalized, supporting a role for this mechanism in antipsychotic drug action in schizophrenia.

Basal ganglia volume in unmedicated patients with schizophrenia is associated with treatment response to antipsychotic medication

We investigated the relationship between basal ganglia volume and treatment response to the atypical antipsychotic medication risperidone in unmedicated patients with schizophrenia. Basal ganglia volumes included the bilateral caudate, putamen, and pallidum and were measured using the Freesurfer automated segmentation pipeline in 23 subjects. Also, baseline symptom severity, duration of illness, age, gender, time off medication, and exposure to previous antipsychotic were measured. Treatment response was significantly correlated with all three regions of the bilateral basal ganglia (caudate, putamen, and pallidum), baseline symptom severity, duration of illness, and age but not gender, time off antipsychotic medication, or exposure to previous antipsychotic medication. The caudate volume was the basal ganglia region that demonstrated the strongest correlation with treatment response and was significantly negatively correlated with patient age. Caudate volume was not significantly correlated with any other measure. We demonstrated a novel finding that the caudate volume explains a significant amount of the variance in treatment response over the course of 6 weeks of risperidone pharmacotherapy even when controlling for baseline symptom severity and duration of illness.

Peripubertal diazepam administration prevents the emergence of dopamine system hyperresponsivity in the MAM developmental disruption model of schizophrenia

Schizophrenia is believed to arise from an interaction of genetic predisposition and adverse environmental factors, with stress being a primary variable. We propose that alleviating anxiety produced in response to stress during a sensitive developmental period may circumvent the dopamine (DA) system alterations that may correspond to psychosis in adults. This was tested in a developmental rat model of schizophrenia based on prenatal administration of the mitotoxin methyl azoxymethanol acetate (MAM). MAM administration leads to a hyperdopaminergic state consisting of an increase in the number of DA neurons firing spontaneously, which correlates with an increased behavioral response to amphetamine. MAM-treated rats exhibited a heightened level of anxiety during adolescence. Peripubertal administration of the antianxiety agent diazepam was found to prevent the increase in DA neuron activity and blunt the behavioral hyperresponsivity to amphetamine in these rats. These data suggest that the pathophysiological factors leading to the onset of psychosis in early adulthood may be circumvented by controlling the response to stress during the peripubertal period.

Hippocampal deep brain stimulation reverses physiological and behavioural deficits in a rodent model of schizophrenia

Subcortical dopamine system dysregulation has been suggested to underlie the positive symptoms of schizophrenia. Recent preclinical investigations and human imaging studies have proposed that the augmented dopamine system function observed in schizophrenia patients may be secondary to aberrant hippocampal activity. Thus, we posit that the hippocampus represents a novel therapeutic target for the treatment of schizophrenia. Here we provide evidence of the effectiveness of a unique approach aimed at decreasing hippocampal function in a rodent model of schizophrenia. Specifically, in a rodent model of schizophrenia, we demonstrate that ventral hippocampal (vHipp) deep brain stimulation (DBS) can normalize aberrant dopamine neuron activity and behaviours associated with positive symptoms. In addition, we provide evidence that this approach may also be effective in restoring deficits in cognitive function, often left unaltered by conventional antipsychotic medications. Therefore, we have provided initial preclinical evidence demonstrating the feasibility of hippocampal DBS as a potential novel approach for the treatment of schizophrenia.

Imaging patients with psychosis and a mouse model establishes a spreading pattern of hippocampal dysfunction and implicates glutamate as a driver

VIDEO ABSTRACT

The hippocampus in schizophrenia is characterized by both hypermetabolism and reduced size. It remains unknown whether these abnormalities are mechanistically linked. Here we addressed this question by using MRI tools that can map hippocampal metabolism and structure in patients and mouse models. In at-risk patients, hypermetabolism was found to begin in CA1 and spread to the subiculum after psychosis onset. CA1 hypermetabolism at baseline predicted hippocampal atrophy, which occurred during progression to psychosis, most prominently in similar regions. Next, we used ketamine to model conditions of acute psychosis in mice. Acute ketamine reproduced a similar regional pattern of hypermetabolism, while repeated exposure shifted the hippocampus to a hypermetabolic basal state with concurrent atrophy and pathology in parvalbumin-expressing interneurons. Parallel in vivo experiments using the glutamate-reducing drug LY379268 and direct measurements of extracellular glutamate showed that glutamate drives both neuroimaging abnormalities. These findings show that hippocampal hypermetabolism leads to atrophy in psychotic disorder and suggest glutamate as a pathogenic driver.

Optimized voxel brain morphometry: association between brain volumes and the response to atypical antipsychotics

To date, few studies have addressed the relationship between brain structure alterations and responses to atypical antipsychotics in schizophrenia. To this end, in this study, magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) were used to assess the relationship between the brain volumes of gray (GM) and white (WM) matters and the clinical response to risperidone or olanzapine in 30 schizophrenia patients. In comparison with healthy controls, the patients in this study showed a bilateral decrease in the anteromedial cerebellar hemispheres, the rectal gyrus and the insula, together with bilateral increases in GM in the basal ganglia. Both patient groups had a significantly smaller volume of WM in a region encompassing the internal and external capsules as compared to the controls. We found an inverse association between striatal size and the degree of clinical improvement, and a direct association between the degree of insular volume deficit and its improvement. The non-responder patient group showed a significant decrease in their left rectal gyrus as compared with the responder group. This study reveals a pattern of structural alterations in schizophrenia associated with the response to risperidone or olanzapine.

Hippocampal dysregulation of dopamine system function and the pathophysiology of schizophrenia

Substantial evidence suggests that psychosis in schizophrenia is associated with dysregulation of subcortical dopamine system function. Here we examine evidence that this dysregulation is secondary to hyperactivity within hippocampal subfields. Enhanced hippocampal activity has been reported in preclinical models and in schizophrenia patients. Moreover, this hippocampal hyperactivity is correlated with enhanced dopamine neuron activity and positive symptoms, respectively. Thus, restoration of hippocampal function could provide a more effective therapeutic approach than current therapeutics based on blockade of dopamine D2 receptors. Indeed, initial studies demonstrate that allosteric modulation of the α5GABA(A) receptor can decrease aberrant dopamine signaling and associated behaviors in a verified rodent model of psychosis.

Left dorsolateral prefrontal cortex dysfunction in medication-naive schizophrenia

Abnormalities in the frontal lobe are considered to be central to the pathology of schizophrenia. Neuroimaging studies indeed report abnormal function of the frontal lobe in schizophrenia patients. However, the nature of these functional abnormalities is unclear, in particular whether they are affected by medication. We therefore investigated whether frontal functioning is already abnormal in first-episode medication-naive schizophrenia, and if so, if this dysfunction is related to symptomatology. Thirty medication-naive male patients with first-episode schizophrenia and 36 matched healthy controls performed a modified working memory task while fMRI data were acquired. During the task, subjects were presented with novel task (NT) and practiced task (PT) memory sets. Compared to controls, patients showed reduced performance during NT and PT. However, both groups performed better during PT, indicating that practice improved performance. Importantly, practice reduced brain activation in both patients and controls, but this effect of practice was significantly smaller in patients compared to controls, specifically in the left dorsolateral prefrontal cortex (DLPFC; p=0.01). The reduced effect of practice on brain activation was related to the severity of negative symptoms and disorganization. These results suggest that DLPFC function is deficient in the early phases of schizophrenia and cannot be attributed to the use of antipsychotics.

Review: The biological basis of antipsychotic response in schizophrenia

Schizophrenia is a severe mental illness affecting approximately 1% of the population worldwide. Antipsychotic drugs are effective in symptom control in up to two-thirds of patients, but in at least one-third of patients the response is poor. The reason for this is not clear, but one possibility is that good and poor responders have different neurochemical pathologies, and may therefore benefit from different treatment approaches. In this selective review we summarise research findings investigating the biological differences between patients with schizophrenia who show a good or a poor response to treatment with antipsychotic drugs.

The functional neuroanatomy of symptom dimensions in schizophrenia: a qualitative and quantitative review of a persistent question

One of the fundamental goals in understanding schizophrenia is linking the observable symptoms to the underlying unobservable pathophysiology. Given recent advances in medical imaging, researchers are increasingly investigating brain-behavior relationships to better understand the neural substrates of negative, positive, and disorganization symptoms in schizophrenia. This review focused on 25 task-related functional magnetic resonance imaging studies and found meaningful small to moderate associations between specific symptom dimensions and regional brain activity. Negative symptoms were related to the functioning of the ventrolateral prefrontal cortex and ventral striatum. Positive symptoms, particularly persecutory ideation, were related to functioning of the medial prefrontal cortex, amygdala, and hippocampus/parahippocampal region. Disorganization symptoms, although less frequently evaluated, were related to functioning of the dorsolateral prefrontal cortex. Surprisingly, no symptom domain had a consistent relationship with the middle or superior temporal regions. While a number of adaptations in experimental design and reporting standards can facilitate this work, current neuroimaging approaches appear to provide a number of consistent links between the manifest symptoms of schizophrenia and brain dysfunction.

Spatio-temporal EEG waves in first episode schizophrenia

OBJECTIVE

Schizophrenia is characterized by a deficit in context processing, with physiological correlates of hypofrontality and reduced amplitude P3b event-related potentials. We hypothesized an additional physiological correlate: differences in the spatio-temporal dynamics of cortical activity along the anterior-posterior axis of the scalp.

METHODS

This study assessed latency topographies of spatio-temporal waves under task conditions that elicit the P3b. EEG was recorded during separate auditory and visual tasks. Event-related spatio-temporal waves were quantified from scalp EEG of subjects with first episode schizophrenia (FES) and matched controls.

RESULTS

The P3b-related task conditions elicited a peak in spatio-temporal waves in the delta band at a similar latency to the P3b event-related potential. Subjects with FES had fewer episodes of anterior to posterior waves in the 2-4 Hz band compared to controls. Within the FES group, a tendency for fewer episodes of anterior to posterior waves was associated with high Psychomotor Poverty symptom factor scores.

CONCLUSIONS

Subjects with FES had altered global EEG dynamics along the anterior-posterior axis during task conditions involving context update.

SIGNIFICANCE

The directional nature of this finding and its association with Psychomotor Poverty suggest this result is related to findings of hypofrontality in schizophrenia.

Audiovisual integration of speech is disturbed in schizophrenia: an fMRI study

Speech perception is an essential part of social interaction. Visual information (lip movements, facial expression) may supplement auditory information in particular under inadvertent listening situations. Schizophrenia patients have been shown to have a deficit in integrating articulatory motions with the auditory speech input. The goal of this study was to investigate the neural basis of this deficit in audiovisual speech processing in schizophrenia patients by using fMRI. Disyllabic nouns were presented in congruent (audio matches visual information) and incongruent conditions in a slow event related fMRI design. Schizophrenia patients (n=15) were compared to age and gender matched control participants. The statistical examination was conducted by analysis of variance with main factors: audiovisual congruency and group membership. The patients' brain activity differed from the control group as evidenced by congruency by group interaction effects. The pertinent brain sites were located predominantly in the right hemisphere and comprised the pars opercularis, middle frontal sulcus, and superior temporal gyrus. In addition, we observed interactions bilaterally in the fusiform gyrus and the nucleus accumbens. We suggest that schizophrenia patients' deficits in audiovisual integration during speech perception are due to a dysfunction of the speech motor system in the right hemisphere. Furthermore the results can be also seen as a reflection of reduced lateralization of language functions to the left hemisphere in schizophrenia.

Critical role of the prefrontal cortex in the regulation of hippocampus-accumbens information flow

The nucleus accumbens (NAc) is an integral part of limbic circuits proposed to play a central role in the pathophysiology of schizophrenia, and is positioned to integrate information from limbic and cortical regions, including the medial prefrontal cortex (mPFC) and the hippocampus. The ventral subiculum (vSub) of the hippocampus, in particular, is proposed to gate information flow within the NAc, a factor that is disrupted in models of schizophrenia. Using in vivo extracellular recordings in anesthetized rats, we examined the response of NAc neurons to vSub stimulation and how this is modulated by the mPFC. We found that inactivation of mPFC by tetrodotoxin attenuates the ability of the vSub to drive spike firing in the NAc. Thus, a contribution of the mPFC is required for the activation of NAc by the vSub. However, when long-term potentiation is induced in the vSub-NAc pathway, the vSub is now capable of driving the NAc without the participation of the mPFC. Moreover, this interaction is dependent on activation of dopaminergic D(2) receptors in the NAc. This work demonstrates the critical role of the mPFC in the ability of vSub to drive NAc neurons in normal anesthetized animals. One model of schizophrenia posits that vSub hyperactivity may underlie both the hyperdopaminergic state and disruption of information flow in this circuit in schizophrenia. Therefore, inactivation of the mPFC, as would occur with mPFC leukotomy in schizophrenia, may prevent the abnormal vSub drive of the NAc.

Switching schizophrenia patients from typical neuroleptics to olanzapine: effects on BOLD response during attention and working memory

Dysfunctional activation of the dorsolateral prefrontal cortex (DLPFC) during working memory (WM) in schizophrenia patients has repeatedly been observed, however little is known about specific medication effects on the modulation of DLPFC activation. We measured activation of DLPFC during a WM task in a longitudinal fMRI study in ten schizophrenia patients first when they received conventional antipsychotics (T1) and a second time after they had been switched to olanzapine (T2). A healthy control group matched for age, handedness and gender was investigated at two corresponding time points. We analyzed the fMRI data with SPM5 in a 2 x 2 x 2 design (group x session x task). Schizophrenia patients showed fewer correct responses compared to healthy controls at both time points. The fMRI data revealed a significant group by task interaction in the bilateral DLPFC and the right parietal cortex, indicating a reduced BOLD response in the patient group. After switching to olanzapine, schizophrenia patients displayed a significant increase in the BOLD response during the 0-back condition in the DLPFC. This study showed that switching patients from conventional neuroleptics to olanzapine did not significantly alter the frontal or parietal BOLD response during working memory task. However, medication status had influences on the activation during attentional task (0-back), emphasizing the importance of baseline selection in pharmacological fMRI studies.

FDG-PET in never-previously medicated psychotic adolescents treated with olanzapine or haloperidol

We acquired Positron emission tomography with 18-F-deoxyglucose (FDG-PET) and anatomical MRI in 30 never-previously medicated psychotic adolescents (ages 13-20). (FDG-PET) was obtained at baseline and after 8-9 weeks of a randomized double-blind trial of either olanzapine or haloperidol. Neuropsychological tests of executive function were also obtained. Patients carried out the serial verbal learning task, a modification of the California Verbal Learning Test, during the uptake of the FDG. PET scans were coregistered with spoiled gradient MRI (TR=24, TE=5, flip angle 40 degrees, slice thickness 1.2 mm, field of view 230 mm) for accurate anatomical identification of regions of interest traced on the MRI. Twenty-two of the thirty patients completed the second PET and clinical evaluation. Individuals treated with olanzapine increased relative metabolic rates in the frontal lobe more than the occipital lobe while patients treated with haloperidol failed to increase frontal metabolic rates and did not show an anteroposterior gradient in medication response. Haloperidol increased striatal metabolic rate more than olanzapine. Both drugs increased thalamic metabolic rates and this increase was significantly larger in younger (age 13-15) than older (16-21) patients.

Positron emission tomography imaging of risperidone augmentation in serotonin reuptake inhibitor-refractory patients

We studied 15 nondepressed patients with obsessive-compulsive disorder (OCD) who were nonresponders to serotonin reuptake inhibitors with an additive trial of risperidone. Positron emission tomography with (18)F-deoxyglucose and magnetic resonance imaging was obtained at baseline and following 8 weeks of either risperidone or placebo in a double-blind parallel group design. Risperidone treatment was associated with significant increases in relative metabolic rate in the striatum, cingulate gyrus, the prefrontal cortex, especially in the orbital region, and the thalamus. Four of 9 patients who received risperidone showed clinical improvement (CGI score of 1 or 2 at 8 weeks) while none of the 6 patients who received placebo showed improvement. Patients with low relative metabolic rates in the striatum and high relative metabolic rates in the anterior cingulate gyrus were more likely to show a clinical response. These metabolic predictors of clinical response are consistent with earlier PET studies showing similar prediction when either neuroleptics or serotonin reuptake inhibitor treatments are administered individually. Our results are consistent with a frontostriatal circuit change related to both dopaminergic and serotonergic systems and with the presence of psychopharmacological subtypes within OCD.

Dorsolateral prefrontal and superior temporal volume deficits in first-episode psychoses that evolve into schizophrenia

Regions with a likely involvement in schizophrenia may differ between patients with first-episodes of psychosis respectively with and without evolution into schizophrenia following the initial episode. We have used magnetic resonance imaging (MRI) to assess the volumes of dorsolateral prefrontal (DLPF) and superior temporal gyrus (STG) in a group of 37 first-episode psychotic patients. After an initial MRI study performed by the time of the first episode, the subjects were followed for two years. After this period 22 cases were diagnosed with schizophrenia, while the other 15 did not show clinical evidence for this illness. A Talairach-based tool was used for segmentation and volumetry of the MRI scans. A group of 44 healthy controls was used for comparison and, using lineal regression, to control for the normal effects of age and intracranial volume on the regional parameters of the patients. By the time of their first episode, patients with schizophrenia had significantly less grey matter in the right DLPF and STG regions as compared to both controls and FE without schizophrenia. Nevertheless, these parameters could not predict final diagnosis in a discriminant analysis model. Our findings indicate that subtle structural defects are already found by the time of the first psychotic break in schizophrenia, although clinical implications for these differences seem unclear.

Dorsolateral prefrontal cortex contribution to abnormalities of the P300 component of the event-related potential in schizophrenia

Abnormalities of the P300 component of the event-related potential are a common finding in schizophrenia. It seems possible that the dysfunction in the dorsolateral prefrontal (DLPF) region that has been reported in schizophrenia contributes to this finding. To explore this possibility, we calculated the relationship between, on the one hand, P300 latency and amplitude and, on the other hand, the degree of DLPF atrophy (as measured by magnetic resonance imaging) and metabolic activity during an attentional task (as measured by positron emission tomography). Seventeen schizophrenia patients with a brief duration of illness and minimal exposition to treatment and 25 healthy controls were studied. Patients exhibited significantly lower metabolic activity in the DLPF region, but they did not show cortical atrophy. P300 amplitude was also significantly reduced in the schizophrenia patients compared with the controls. Right DLPF region metabolic activity correlated significantly with P300 amplitude. This pattern remained after partialling out the influence of activity in the hippocampus, superior temporal gyrus and parietal lobe. It is therefore suggested that the prefrontal cortex could be implicated in the P300 amplitude reduction in schizophrenia.

Neural correlates of adjunctive rivastigmine treatment to antipsychotics in schizophrenia: a randomized, placebo-controlled, double-blind fMRI study

Facilitation of central cholinergic activity may form a potential treatment strategy for cognitive impairment in schizophrenia. In a randomized, placebo-controlled, double-blind, parallel-group design, we investigated the neural correlates of cognitive effects of rivastigmine, an acetylcholinesterase inhibitor, given as an add-on therapy to antipsychotic-treated schizophrenia patients. Thirty-six chronic schizophrenia patients with mild cognitive impairment took part. After 1 week on placebo (baseline), all patients entered a double-blind protocol; 18 were allocated to receive rivastigmine and 18 placebo for the next 12 weeks (final sample with usable imaging data: 11 patients on rivastigmine, 10 on placebo). All patients underwent functional magnetic resonance imaging during a parametric 'n-back' task, involving monitoring of dots in particular locations on a screen at a given delay from the original occurrence, twice: at baseline and 12 weeks post-rivastigmine/placebo treatment. Compared to placebo, rivastigmine produced only a small and non-significant improvement in task accuracy across all conditions with no change in response latency, and increased activity in the extrastriate visual cortex in areas associated with visual and spatial attention but not in any region within the working memory network. Our observations suggest that cholinergic enhancement with rivastigmine at doses known to be effective in Alzheimer's disease does not produce strong and clinically meaningful cognitive and neural changes in schizophrenia patients treated with atypical antipsychotics although the neural effects in terms of enhanced neuronal activity in regions associated with visual and spatial attention are consistent with those reported previously with cholinergic enhancement in healthy subjects.

Dysfunction of ventral striatal reward prediction in schizophrenia

BACKGROUND

Negative symptoms may be associated with dysfunction of the brain reward system in schizophrenia. We used functional magnetic resonance imaging (fMRI) to assess the BOLD response in the ventral striatum of unmedicated schizophrenics during presentation of reward-indicating and loss-indicating stimuli.

METHODS

A total of 10 schizophrenic men (7 never medicated, 3 unmedicated for at least 2 years) and 10 age-matched healthy male volunteers participated in an incentive monetary delay task, in which visual cues predicted that a rapid response to a subsequent target stimulus would result either in monetary gain or loss or would have no consequence.

RESULTS

Compared to healthy controls, unmedicated schizophrenics showed reduced ventral striatal activation during the presentation of reward-indicating cues. Decreased activation of the left ventral striatum was inversely correlated with the severity of negative (and trendwise positive) symptoms.

DISCUSSION

Reduced activation in one of the central areas of the brain reward system, the ventral striatum, was correlated with the severity of negative symptoms in medication-free schizophrenics. In unmedicated schizophrenic patients, a high striatal dopamine turnover may increase the "noise" in the reward system, thus interfering with the neuronal processing of reward-predicting cues by phasic dopamine release. This, in turn, may contribute to negative symptoms as such as anhedonia, apathy, and loss of drive and motivation.

Volumetric MRI measurement of caudate nuclei in antipsychotic-naive patients suffering from a first episode of psychosis

Magnetic resonance imaging (MRI) studies measuring basal ganglia volumes in first episode patients suggest that treatment with typical neuroleptics leads to alteration in these brain structures. However, caudate nuclei volumes (CNV) of untreated first-episode patients may even be smaller than in healthy controls. We investigated whether CNV of newly diagnosed neuroleptic-naive psychotic patients differ as compared to an age- and sex-matched healthy control group to detect possible treatment effects early in the course of this illness. Magnetic resonance images were acquired in 37 un-medicated psychotic patients and 37 healthy controls. Ten of the patients were re-examined after 12 weeks of treatment with the second generation antipsychotic quetiapine. Regions of interest (ROI) delineating the caudate nuclei bilaterally were drawn manually using Brain Image software. The neuroleptic-naive patients showed a mean CNV of 8.40 cc (SD=1.01) and the controls of 8.55 cc (SD=1.16). There was no significant difference between groups (F=.600; P=.441). In contrast to previous studies in patients treated with typical neuroleptics, this cross-sectional MRI study did not find significant differences in CNV of neuroleptic-naive first-episode patients compared to healthy controls.

Prefrontal atrophy in first episodes of schizophrenia associated with limbic metabolic hyperactivity

Reduced volume and activity of the prefrontal (PF) cortical gray matter (GM) and hippocampal hypermetabolism are repeated findings in schizophrenia. There is still an information deficit about the significance of reduction of PF GM in schizophrenia, and a simultaneous study of PF anatomy and activity and limbic metabolism can contribute to fill that deficit. In order to do so, we used positron emission tomography (PET) with 18-fluoro-deoxy-glucose (FDG) during an attention task and magnetic resonance imaging (MRI) to study a sample of first episodes of psychosis. We included 21 first episodes (FE) of psychosis and 16 healthy controls. A diagnosis of schizophrenia was confirmed in the follow-up in eleven of these patients and ruled out in the remaining 10 cases. Volumes of PF GM were determined and also activity in the same region and in the hippocampus. Residual GM was estimated in the PF region as a quantitative measurement of the degree of atrophy in each individual, using age and intracranial volume data from a set of 45 healthy controls and linear regression. Patients with schizophrenia had lower PF metabolic activation and greater hippocampal activity than controls. FE patients without schizophrenia were no different in any parameter as compared to controls. Patients with schizophrenia presented an inverse and significant association between GM deficit and hippocampal activity that was not observed in controls or in patients without schizophrenia. The same association was previously described by our group using PET in the resting state in recent-onset and chronic patients with schizophrenia. These findings support a loss in PF inhibitory capacity as a possible link between anatomical and functional alterations in schizophrenia.