Dysfunction of dorsolateral prefrontal cortex in antipsychotic-naïve schizophreniform psychosis

Early efficacy of rTMS intervention at week 2 predicts subsequent responses at week 24 in schizophrenia in a randomized controlled trial

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique for modulating cortical activities and improving neural plasticity. Several studies investigated the effects of rTMS, etc., but the results are inconsistent. This study was designed to examine whether rTMS applied on the left dorsolateral prefrontal cortex (l-DLPFC) showed an effect on improving cognitive deficits in SZ and whether the early efficacy could predict efficacy at subsequent follow-ups. Cognitive ability was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) scale at baseline, weeks 2, 6, and 24. We found a significant interaction between time (weeks 0, 2, 6, and 24) and intervention on immediate memory and RBANS total scores (p ​= ​0.02 and p ​= ​0.04), indicating that both 10-Hz and 20-Hz rTMS stimulations had a delayed beneficial effect on immediate memory in SZ. Moreover, we found that 20-Hz rTMS stimulation, but not 10-Hz rTMS improved immediate memory at week 6 compared to the sham group (p ​= ​0.029). More importantly, improvements in immediate memory at week 2 were positively correlated with improvements at week 24 (β ​= ​0.461, t ​= ​3.322, p ​= ​0.002). Our study suggests that active rTMS was beneficial for cognitive deficits in patients with SZ. Furthermore, efficacy at week 2 could predict the subsequent efficacy at 24-week follow-up.

Navigating Exploitative Traps: Unveiling the Uncontrollable Reward Seeking of Internet Gaming Disordered Individuals

BACKGROUND

Internet Gaming Disorder (IGD) involves an imbalance in the brain's dual-system, characterized by heightened reward-seeking and diminished cognitive control, which leads to decision-making challenges. The exploration-exploitation strategy is key to decision-making, but how IGD affects this process is unclear.

METHODS

To investigate the impact of IGD on decision-making, a modified version of the two-armed bandit task was employed. Participants included 41 IGD individuals and 44 healthy control (HC) individuals. The study assessed the strategies used by participants in the task, particularly focusing on the exploitation-exploration strategy. Additionally, functional magnetic resonance imaging (fMRI) was used to examine brain activation patterns during decision-making and estimation phasess.

RESULTS

The study found that individuals with IGD demonstrated a higher reliance on exploitative strategies in decision-making due to their elevated value-seeking tendencies and decreased cognitive control. IGD individuals also displayed heightened activation in the pre-supplementary motor area (preSMA) and the ventral striatum (VS) compared to the HC group in both decision-making and estimation phases. Meanwhile, the prefrontal cortex (PFC) showed more inhibition in IGD individuals than in the HC group during exploitative strategies. This inhibition was found to decrease as cognitive control diminished.

CONCLUSION

The study concludes that the imbalance in the development of the dual-system in individuals with IGD may lead to an over-reliance on exploitative strategies. This imbalance, marked by increased reward-seeking and reduced cognitive control, contributes to difficulties in decision-making and value-related behavioral processes in IGD individuals.

Cognitive [Computational] Neuroscience Test Reliability and Clinical Applications for Serious Mental Illness (CNTRaCS) Consortium: Progress and Future Directions

The development of treatments for impaired cognition in schizophrenia has been characterized as the most important challenge facing psychiatry at the beginning of the twenty-first century. The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) project was designed to build on the potential benefits of using tasks and tools from cognitive neuroscience to better understanding and treat cognitive impairments in psychosis. These benefits include: (1) the use of fine-grained tasks that measure discrete cognitive processes; (2) the ability to design tasks that distinguish between specific cognitive domain deficits and poor performance due to generalized deficits resulting from sedation, low motivation, poor test taking skills, etc.; and (3) the ability to link cognitive deficits to specific neural systems, using animal models, neuropsychology, and functional imaging. CNTRICS convened a series of meetings to identify paradigms from cognitive neuroscience that maximize these benefits and identified the steps need for translation into use in clinical populations. The Cognitive Neuroscience Test Reliability and Clinical Applications for Schizophrenia (CNTRaCS) Consortium was developed to help carry out these steps. CNTRaCS consists of investigators at five different sites across the country with diverse expertise relevant to a wide range of the cognitive systems identified as critical as part of CNTRICs. This work reports on the progress and current directions in the evaluation and optimization carried out by CNTRaCS of the tasks identified as part of the original CNTRICs process, as well as subsequent extensions into the Positive Valence systems domain of Research Domain Criteria (RDoC). We also describe the current focus of CNTRaCS, which involves taking a computational psychiatry approach to measuring cognitive and motivational function across the spectrum of psychosis. Specifically, the current iteration of CNTRaCS is using computational modeling to isolate parameters reflecting potentially more specific cognitive and visual processes that may provide greater interpretability in understanding shared and distinct impairments across psychiatric disorders.

Regional Cerebral Blood Flow Correlates of Neuropsychiatric Symptom Domains in Early Alzheimer’s Disease

Although various neuropsychiatric symptoms are frequently accompanied with Alzheimer’s disease (AD) and pose a substantial burden to both patients and caregivers, their neurobiological underpinnings remain unclear. This study investigated associations between regional cerebral blood flow (rCBF) and neuropsychiatric symptom domains in early AD. A total of 59 patients with early AD underwent brain technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) scans. Neuropsychiatric symptoms were assessed by the Neuropsychiatric Inventory and clustered into the affective, apathy, hyperactivity, and psychotic domains. A voxel-wise multiple regression analysis was performed with four domain scores as independent variables and age, sex, and Mini-Mental State Examination scores as covariates. The affective domain score was negatively correlated with rCBF in the prefrontal cortex, thalamus, and caudate. The apathy domain score showed inverse correlations with rCBF in the prefrontal and pre/postcentral gyri and midbrain. Patients with higher hyperactivity domain scores had increased rCBF in the prefrontal and temporal lobes. The psychotic symptom domain was positively correlated with rCBF in the cuneus and negatively associated with rCBF in the prefrontal, cingulate, and occipital regions and putamen. The score of each neuropsychiatric symptom domain showed the differential correlates of brain perfusion, while altered rCBF in the prefrontal cortex was found in all domains. Although preliminary, our results may suggest common and distinct patterns of rCBF underlying neuropsychiatric symptoms in early AD. Further studies with larger samples and control participants are warranted to confirm these findings.

Spatial and chronic differences in neural activity in medicated and unmedicated schizophrenia patients

•

The medicated schizophrenia group yielded concordant activity among three right lateralized frontal clusters and a left lateralized parietal cluster.

•

The unmedicated schizophrenia group yielded concordant activity among right lateralized frontal-parietal regions.

•

A neural compensatory mechanism in schizophrenia.

A major caveat with investigations on schizophrenic patients is the difficulty to control for medication usage across samples as disease-related neural differences may be confounded by medication usage. Following a thorough literature search (632 records identified), we included 37 studies with a total of 740 medicated schizophrenia patients and 367 unmedicated schizophrenia patients. Here, we perform several meta-analyses to assess the neurofunctional differences between medicated and unmedicated schizophrenic patients across fMRI studies to determine systematic regions associated with medication usage. Several clusters identified by the meta-analysis on the medicated group include three right lateralized frontal clusters and a left lateralized parietal cluster, whereas the unmedicated group yielded concordant activity among right lateralized frontal-parietal regions. We further explored the prevalence of activity within these regions across illness duration and task type. These findings suggest a neural compensatory mechanism across these regions both spatially and chronically, offering new insight into the spatial and temporal dynamic neural differences among medicated and unmedicated schizophrenia patients.

Repetitive transcranial magnetic stimulation for psychiatric symptoms in long-term hospitalized veterans with schizophrenia: A randomized double-blind controlled trial

Multiple lines of evidence demonstrate that high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) may improve clinical outcomes in patients with schizophrenia (SCZ). However, the efficacy of HF-rTMS on psychiatric symptoms remains unknown in veterans with SCZ. This study aimed to investigate whether HF-rTMS was beneficial in alleviating the clinical symptoms in veterans with SCZ. Forty-seven long-term hospitalized veterans with SCZ were randomly allocated to receive neuronavigated 10 Hz rTMS or sham stimulation over the left dorsolateral prefrontal cortex once daily for four consecutive weeks. Symptoms were assessed by using the Positive and Negative Syndrome Scale at baseline and at the end of week 4. We also collected easily available routine biochemical markers including blood sugar, lipid profiles, hormone, and blood cell counts, considering that these markers may potentially be used to predict the outcomes of rTMS treatment. We found that there was a significant interaction effect of time and group on the positive symptoms. Compared with the sham group, the positive factor score of veterans with SCZ was significantly decreased after treatment in the real rTMS group. Interestingly, the improvement of positive symptoms from baseline to 4-week follow-up was significantly associated with the whole white blood cells (WBC) counts at baseline in the real rTMS group, and baseline WBC counts were predictive of the symptom improvement after rTMS treatment. Our findings indicate that add-on 10 Hz rTMS is beneficial for clinical symptoms in veterans with SCZ. In addition, the baseline WBC counts were predictive of the outcomes after treatment.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT03774927.

Distinct patterns of blood oxygenation in the prefrontal cortex in clinical phenotypes of schizophrenia and bipolar disorder

BACKGROUND

Schizophrenia (SZ) and bipolar disorder (BD) are characterized by different clinical symptoms, and have previously been considered as categorically separate. However, several lines of evidence controversially suggest that these two disorders may run on a continuum. While it is therefore important to evaluate the subtle differences between SZ and BD, few studies have investigated the difference of brain functioning between the two by focusing on the common symptoms of cognitive functioning and impulsivity, rather than positive/negative and mood symptoms. Recent developments in near-infrared spectroscopy (NIRS) technology have enabled noninvasive assessment of brain function in people with psychiatric disorders.

METHODS

Near-infrared spectroscopy (NIRS) using 24-channels was conducted during the verbal fluency task (VFT) and Stroop color-word task (SCWT) in 38 patients diagnosed with SZ, 34 patients with BD, and 26 age- and sex-matched healthy controls.

RESULTS

Oxyhemoglobin changes in the prefrontal cortex (PFC) were significantly lower particularly in the SZ compared to control group during the VFT. On the other hand, these were significantly lower particularly in the BD and SZ group to control group during the SCWT. Regression analysis showed that hemodynamic changes were significantly correlated with verbal memory and impulsivity in both disorders.

CONCLUSION

These findings suggest that different hemodynamic responses in the prefrontal cortex might reflect cognitive functioning and impulsivity, providing a greater insight into SZ and BD pathophysiology.

Relationships between dorsolateral prefrontal cortex metabolic change and cognitive impairment in first-episode neuroleptic-naive schizophrenia patients

The present study aimed to explore the possible associations between the dorsolateral prefrontal cortex (DLPFC) metabolites and the cognitive function in first-episode schizophrenia (FES).This study included 58 patients with FES (29 males and 29 females; mean age, 22.66 ± 7.64 years) recruited from the First Affiliated Hospital, College of Medicine, Zhejiang University, and 43 locally recruited healthy controls (16 males and 27 females; mean age, 23.07 ± 7.49 years). The single-voxel proton magnetic resonance spectroscopy was used to measure the levels of N-acetylaspartate (NAA); complex of glutamate, glutamine, and γ-aminobutyric acid (Glx); choline-containing compounds; and myo-inositol in the DLPFC. The ratios of metabolites to creatine (Cr) were calculated. The cognitive function was assessed by Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB). Correlation analysis was used to assess the relationships between the DLPFC metabolites and the cognitive function.Compared with the healthy controls, the patients with FES showed significantly reduced scores in each part of the MCCB, significantly reduced NAA/Cr, and significantly increased Glx/Cr in the left DLPFC. Poor performance in verbal learning and visual learning was correlated to the reduced NAA/Cr ratio in the left DLPFC.These findings suggest that a lower NAA/Cr ratio in the left DLPFC is associated with the cognitive deficits in patients with FES, and may be an early biochemical marker for the cognitive impairment in schizophrenia.

The Role of Muscarinic Receptors in the Pathophysiology of Mood Disorders: A Potential Novel Treatment?

The central cholinergic system has been implicated in the pathophysiology of mood disorders. An imbalance in central cholinergic neurotransmitter activity has been proposed to contribute to the manic and depressive episodes typical of these disorders. Neuropharmacological studies into the effects of cholinergic agonists and antagonists on mood state have provided considerable support for this hypothesis. Furthermore, recent clinical studies have shown that the pan-CHRM antagonist, scopolamine, produces rapid-acting antidepressant effects in individuals with either major depressive disorder (MDD) or bipolar disorder (BPD), such as bipolar depression, contrasting the delayed therapeutic response of conventional mood stabilisers and antidepressants. This review presents recent data from neuroimaging, post-mortem and genetic studies supporting the involvement of muscarinic cholinergic receptors (CHRMs), particularly CHRM2, in the pathophysiology of MDD and BPD. Thus, novel drugs that selectively target CHRMs with negligible effects in the peripheral nervous system might produce more rapid and robust clinical improvement in patients with BPD and MDD.

Early psychosis research at Orygen, The National Centre of Excellence in Youth Mental Health

BACKGROUND

Specialised early intervention (SEI) programs have offered individuals with psychotic disorders and their families new hope for improving illness trajectories and outcomes. The Early Psychosis Prevention and Intervention Centre (EPPIC) was one of the first SEI programs developed in the world, providing services for young people experiencing their first episode of psychosis.

METHODS

We conducted a narrative synthesis of controlled and uncontrolled studies that have been conducted at EPPIC.

DISCUSSION

The history of the EPPIC model is first described. This is followed by a discussion of clinical research emerging from EPPIC, including psychopharmacological, psychotherapeutic trials and outcome studies. Neurobiological studies are also described. Issues pertaining to the conduct of clinical research and future research directions are then described. Finally, the impact of the EPPIC model on the Australian environment is discussed.

Metamemory in patients with schizophrenia measured by the feeling of knowing

Cognitive awareness in patients with schizophrenia is crucial for clinical management of cognitive deficits. Traditional approaches using self-report inventories have questionable validity and reliability. Using the Feeling-of-Knowing (FOK) procedure to measure metamemory might overcome such weakness. A cross-sectional study comparing 40 patients and 40 demographically matched normal controls, using a recall-judgment-recognition (RJR) procedure and the Hamann coefficient was conducted to examine whether patients with schizophrenia have FOK deficits and what neurocognitive mechanism might account for these deficits. General IQ, executive function, and memory tests were also assessed. The results show that as a group, patients with schizophrenia had impaired FOK ability and evidenced a disposition to underestimate their memory performance. However, patient's FOK ability was variable, with 42.5% of patients exhibited a below chance level performance. There were marked relationships between FOK and set formation and visual recognition abilities in healthy controls, while such feature was not evident in patient group. These findings are in line with the prefrontal cortex dysfunction, reduced intrapsychic monitoring ability, and impaired utilization of mental resources noticed in patients with schizophrenia. A routine evaluation of metamemory function by FOK might be helpful for designing customized cognitive rehabilitation programs considering their missed estimation of memory capacity.

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.

N-Acetyl-Aspartate Level is Decreased in the Prefrontal Cortex in Subjects At-Risk for Schizophrenia

Reduced N-acetyl-aspartate (NAA) levels have been reported in the prefrontal cortex (PFC) in patients with schizophrenia using proton magnetic resonance spectroscopy. However, it is unclear whether this NAA reduction predates the illness onset and is reported in subjects at-risk for developing schizophrenia (HRS). The aim of this study was to assess NAA levels in the PFC in HRS. We hypothesized that HRS display lower NAA levels than healthy controls in the PFC. Studies assessing levels of NAA/Creatine (NAA/Cr) in the PFC in HRS were extracted from literature. Meta-analysis tools were used to compute effect sizes of nine selected studies meeting our inclusion criteria (clinical and/or genetic HRS, groups of HRS, and healthy controls matched for age and gender, spectral acquisition in the PFC). We reported that HRS exhibited a significant lower NAA/Cr level (2.15 ± 0.29; n = 208) than healthy controls (2.21 ± 0.32; n = 234) in the PFC with a medium pooled effect size [Hedges's g = -0.42; 95% confidence interval: (-0.61; -0.23); p < 0.0001] corresponding to an average 5.7% of NAA/Cr decrease. Secondary analysis revealed that this reduction was observed in young HRS (<40 years old) who have not reached the peak age of risk for schizophrenia (-11%, g = -0.82, p < 0.00001) but not in old HRS (>40 years old) who have already passed the peak age (g = 0.11, p = 0.56), when they are compared with their matched healthy controls. Our findings suggest that the NAA/Cr reduction in the PFC reported in patients with schizophrenia is observable only in HRS who have not passed the peak age of risk for schizophrenia. NAA/Cr level in the PFC could therefore be considered as a biological vulnerability marker of schizophrenia.

Neurocognitive profile and its association with psychopathology in first-degree relatives of patients with schizophrenia. a case-control study

BACKGROUND

People with schizophrenia show a broad range of neurocognitive deficits, which are considered as core features of the disorder and are thought to be partly heritable. Similar deficits, albeit at a lesser degree, have been also found in their healthy biological relatives. These deficits, if better characterized, might represent underlying vulnerable traits for psychosis.

METHODS

This case-control study compared neurocognitive functioning of adult first-degree relatives of patients with schizophrenia (SCZ-RELs) (n=55) with healthy control subjects (n=55) and explored its association with the negative symptoms. Subjects in both study and control group were assessed with an extensive neurocognitive test battery (Trail Making test, Phonemic Verbal fluency, Wisconsin Card Sorting Test, Bushke Fuld Test, Stroop Test, n-Back and Digit span) and a set of clinical measures (SANS, GAF and DAS).

RESULTS

SCZ-RELs were more significantly impaired on executive function tasks (i.e. Wisconsin Card Sorting Test and the Phonemic Verbal fluency) and displayed significantly more severe negative symptoms and poorer social functioning than control subjects. Significant correlations between neurocognitive measures and negative symptoms were found in the study group, whereas no significant correlations were detected among the controls.

DISCUSSION

Subtle executive impairments, associated with negative symptoms, are shown to be evident in healthy relatives of patients with schizophrenia. These deficits, which reflect subtle dysfunction in concept formation, flexibility and mental shifting, may be seen as potential phenotypic markers of vulnerability for schizophrenia. This raises the question of underlying prefrontal dysfunction as core feature of the disorder.

From sensorimotor inhibition to freudian repression: insights from psychosis applied to neurosis

First, three case studies are presented of psychotic patients having in common an inability to hold something down or out. In line with other theories on psychosis, we propose that a key change is at the efference copy system. Going back to Freud's mental apparatus, we propose that the messages of discharge of the motor neurons, mobilized to direct perception, also called "indications of reality," are equivalent to the modern efference copies. With this key, the reading of the cases is coherent with the psychodynamic understanding of psychosis, being a downplay of secondary processes, and consequently, a dominance of primary processes. Moreover, putting together the sensorimotor idea of a failure of efference copy-mediated inhibition with the psychoanalytic idea of a failing repression in psychosis, the hypothesis emerges that the attenuation enabled by the efference copy dynamics is, in some instances, the physiological instantiation of repression. Second, we applied this idea to the mental organization in neurosis. Indeed, the efference copy-mediated attenuation is thought to be the mechanism through which sustained activation of an intention, without reaching it - i.e., inhibition of an action - gives rise to mental imagery. Therefore, as inhibition is needed for any targeted action or for normal language understanding, acting in the world, or processing language, structurally induces mental imagery, constituting a subjective unconscious mental reality. Repression is a special instance of inhibition for emotionally threatening stimuli. These stimuli require stronger inhibition, leaving (the attenuation of) the motor intentions totally unanswered, in order to radically prevent execution which would lead to development of excess affect. This inhibition, then, yields a specific type of motor imagery, called "phantoms," which induce mental preoccupation, as well as symptoms which, especially through their form, refer to the repressed motor fragments.

Multi-channel near-infrared spectroscopy reveals reduced prefrontal activation in schizophrenia patients during performance of the kana Stroop task

The purpose of the present study was to investigate the activity of frontal lobe of patients with schizophrenia during performance of two Japanese versions of the Stroop task (kana and kanji) by measuring changes in the concentration of oxygenated hemoglobin (oxyHb) with near-infrared spectroscopy (NIRS). Fourteen schizophrenia patients and 14 age- and gender-matched healthy control subjects participated in the study after giving consent. The relative changes of concentrations of oxyHb were measured by NIRS during performance of the Stroop task. Significant Stroop effects, as measured by the number of correct responses, were observed with both the kana and the kanji versions. Analysis of NIRS data revealed that the schizophrenia patients showed reduced activation in the prefrontal cortex compared to healthy controls during performance of the kana Stroop task, and that both schizophrenia patients and healthy controls showed lack of activity in the prefrontal cortex during performance of the kanji Stroop task. The results of the present study suggest the possibility that the kana Stroop task cause a greater Stroop effect than the kanji Stroop task, and schizophrenia patients show decreased prefrontal vascular reactivity associated with the inhibition required during the performance of the kana Stroop task.

Age of onset of schizophrenia: perspectives from structural neuroimaging studies

Many of the major neuropsychiatric illnesses, including schizophrenia, have a typical age of onset in late adolescence. Late adolescence may reflect a critical period in brain development making it particularly vulnerable for the onset of psychopathology. Neuroimaging studies that focus on this age range may provide unique insights into the onset and course of psychosis. In this review, we examine the evidence from 2 unique longitudinal cohorts that span the ages from early childhood through young adulthood; a study of childhood-onset schizophrenia where patients and siblings are followed from ages 6 through to their early twenties, and an ultra-high risk study where subjects (mean age of 19 years) are studied before and after the onset of psychosis. From the available evidence, we make an argument that subtle, regionally specific, and genetically influenced alterations during developmental age windows influence the course of psychosis and the resultant brain phenotype. The importance of examining trajectories of development and the need for future combined approaches, using multimodal imaging together with molecular studies is discussed.

Gray matter in first-episode schizophrenia before and after antipsychotic drug treatment. Anatomical likelihood estimation meta-analyses with sample size weighting

BACKGROUND

Cerebral morphological abnormalities in schizophrenia may be modulated by treatment, chronicity, and duration of illness. Comparing brain imaging studies of individuals with first-episode schizophrenia and neuroleptic naive (NN-FES) with that of their neuroleptic-treated counterparts (NT-FES) can help to dissect out the effect of these potential confounders.

METHODS

We used the anatomical likelihood estimation method to compare voxel-based morphometric studies of NN-FES (n = 162 patients) and NT-FES (n = 336 patients) studies. The analysis included a sample size weighting step based on the Liptak-Stouffer method to reflect the greater power of larger studies.

RESULTS

Patient samples were matched for age, gender, and duration of illness. An extensive network of gray matter deficits in frontal, temporal, insular, striatal, posterior cingulate, and cerebellar regions was detected in the NN-FES samples as compared with healthy controls. Major deficits were detected in the frontal, superior temporal, insular, and parahippocampal regions for the NT-FES group compared with the NN-FES group. In addition, the NT-FES group showed minor deficits in the caudate, cingulate, and inferior temporal regions compared with the NN-FES group. There were no regions with gray matter volumetric excess in the NT-FES group.

CONCLUSION

Frontal, striato-limbic, and temporal morphological abnormalities are present in the early stage of schizophrenia and are unrelated to the effects of neuroleptic treatment, chronicity, and duration of illness. There may be dynamic effects of treatment on striato-limbic and temporal, but not frontal, regional gray matter volumes of the brain.

Regional increase in P-glycoprotein function in the blood-brain barrier of patients with chronic schizophrenia: a PET study with [(11)C]verapamil as a probe for P-glycoprotein function

P-glycoprotein (P-gp), a major efflux pump in the blood-brain barrier (BBB) has a profound effect on entry of drugs, peptides and other substances into the central nervous system (CNS). The brain's permeability can be negatively influenced by modulation of the transport function of P-gp. Inflammatory mediators play a role in schizophrenia, and may be able to influence the integrity of the BBB, via P-gp modulation. We hypothesized that P-gp function in the BBB is changed in patients with schizophrenia. Positron-emission tomography was used to measure brain uptake of [(11)C]verapamil, which is normally extruded from the brain by P-gp. We found that patients with chronic schizophrenia under treatment with antipsychotic drugs compared with healthy controls showed a significant decrease in [(11)C]verapamil uptake in the temporal cortex, the basal ganglia, and the amygdala, and amygdalae, and a trend towards a significant decrease was seen throughout the brain. The decrease of [(11)C]verapamil uptake correlates with an increased activity of the P-gp pump. Increased P-gp activity may be a factor in drug resistance in schizophrenia, induced by the use of antipsychotic agents.

Positive schizotypy scores correlate with left visual field interference for negatively valenced emotional words: A lateralized emotional Stroop study

Fourteen men scoring high and 14 men scoring low on a positive schizotypy scale participated in a lateralized emotional Stroop task. Vocal reaction times for color naming of neutral, positive and negative emotional words were recorded. Across participants, the color naming of neutral and emotional words was slightly faster to right than to left visual field presentations. In men with high scores on positive schizotypy, the presentation of negative words to the left visual field (right hemisphere) resulted in significant affective interference with color naming, which was significantly larger than in men with low scores. Correlational analysis also showed that positive schizotypy was significantly associated with emotional interference in response to LVF negative words. The outcome is discussed in terms of right hemispheric engagement in negative emotions in high positive schizotypic men.

Cognitive performance is related to cortical grey matter volumes in early stages of schizophrenia: a population-based study of first-episode psychosis

BACKGROUND

Neuropsychological deficits have been reported in association with first-episode psychosis (FEP). Reductions in grey matter (GM) volumes have been documented in FEP subjects compared to healthy controls. However, the possible inter-relationship between the findings of those two lines of research has been scarcely investigated.

OBJECTIVE

To investigate the relationship between neuropsychological deficits and GM volume abnormalities in a population-based sample of FEP patients compared to healthy controls from the same geographical area.

METHODS

FEP patients (n=88) and control subjects (n=86) were evaluated by neuropsychological assessment (Controlled Oral Word Association Test, forward and backward digit span tests) and magnetic resonance imaging using voxel-based morphometry.

RESULTS

Single-group analyses showed that prefrontal and temporo-parietal GM volumes correlated significantly (p<0.05, corrected) with cognitive performance in FEP patients. A similar pattern of direct correlations between neocortical GM volumes and cognitive impairment was seen in the schizophrenia subgroup (n=48). In the control group, cognitive performance was directly correlated with GM volume in the right dorsal anterior cingulate cortex and inversely correlated with parahippocampal gyral volumes bilaterally. Interaction analyses with "group status" as a predictor variable showed significantly greater positive correlation within the left inferior prefrontal cortex (BA46) in the FEP group relative to controls, and significantly greater negative correlation within the left parahippocampal gyrus in the control group relative to FEP patients.

CONCLUSION

Our results indicate that cognitive deficits are directly related to brain volume abnormalities in frontal and temporo-parietal cortices in FEP subjects, most specifically in inferior portions of the dorsolateral prefrontal cortex.

Neurocognitive profile analysis in obsessive-compulsive disorder

Although neurocognitive deficits have been identified in obsessive-compulsive disorder (OCD), little research has focused on whether these deficits are generalized or specific to a given cognitive domain. We assessed the relative strengths and weaknesses of 26 adult patients with OCD compared to 38 age- and sex-matched healthy volunteers in domains of motor, verbal memory, visual memory, reasoning/problem solving, processing speed processing, and language. Profile analysis revealed an overall neurocognitive deficit of 1/2 standard deviation in OCD patients versus healthy volunteers, with relative weaknesses in motor and processing speed domains. In contrast, relative strengths were observed in language, verbal memory, and reasoning/problem solving. Our findings demonstrate neurocognitive impairment in OCD that may relate to functional outcome in this population. Findings of specific abnormalities on tasks of motor and processing speed are consistent with a hypothesized role of thalamocortical and basal ganglia regions in the pathogenesis of OCD.

Functional brain abnormalities in psychiatric disorders: neural mechanisms to detect and resolve cognitive conflict and interference

In the present article, we review functional neuroimaging studies on interference processing and performance monitoring in three groups of psychiatric disorders, (1) mood disorders, (2) schizophrenia, and (3) obsessive-compulsive disorder (OCD). Ad (1) Behavioral performance measures suggest an impaired interference resolution capability in symptomatic bipolar disorder patients. A series of neuroimaging analyses found alterations in the ACC-DLPFC system in mood disorder (unipolar depressed and bipolar) patients, putatively reflective of an abnormal interplay of monitoring and executive neurocognitive functions. Other studies of euthymic bipolar patients showed relatively decreased interference-related activation in rostroventral PFC which conceivably underlies defective inhibitory control. Ad (2) Behavioral Stroop studies revealed a specific performance pattern of schizophrenia patients (normal RT interference but increased error interference and RT facilitation) suggestive of a deficit in ignoring irrelevant (word) information. Moreover, reduced/absent behavioral post-error and post-conflict adaptation effects suggest alterations in performance monitoring and/or adjustment capability in these patients. Neuroimaging findings converge to suggest a disorder-related abnormal neurophysiology in ACC which consistently showed conflict- and error-related hypoactivation that, however, appeared to be modulated by different factors. Moreover, studies suggest a specific deficit in context processing in schizophrenia, evidently related to activation reduction in DLPFC. Ad (3) Behavioral findings provide evidence for impaired interference resolution in OCD. Neuroimaging results consistently showed conflict- and error-related ACC hyperactivation which--conforming OCD pathogenesis models--can be conclusively interpreted as reflecting overactive performance monitoring. Taken together, interference resolution and performance monitoring appeared to be fruitful concepts in the investigation of neurocognitive deficits in psychiatric disorders.

Neuroimaging and emerging psychotic disorders: the Melbourne ultra-high risk studies

Although the underlying neurobiology of emerging psychotic disorders is not well understood, evidence from structural imaging and other studies support the notion that schizophrenia arises as a consequence of both an 'early neurodevelopmental' disturbance, as well as 'late neurodevelopmental' changes occurring during the initial stages of a psychotic illness, including around the time of transition to illness. In line with this, our longitudinal MRI findings in individuals at ultra-high risk for developing a psychotic illness show that there are excessive neuroanatomical changes in those who convert to psychosis. These aberrant changes are observed most prominently in medial temporal and prefrontal lobe regions. In a further series of longitudinal studies in first-episode psychosis, we have identified changes in prefrontal regions that indicate an accelerated loss of grey matter in patients compared to healthy control subjects. We suggest that the available evidence is consistent with the presence of subtle regionally and temporally specific neurobiological changes through the course of psychosis (Pantelis et al., 2005), including: (1) evidence for early (pre- and peri-natal) neurodevelopmental anomalies, (2) evidence for progressive grey matter loss involving medial temporal and orbital prefrontal regions around the time of transition to illness, and (3) evidence of late (post-pubertal) neurodevelopmental changes soon after the onset of psychosis, involving an acceleration of normal brain maturational processes, associated with significant loss of grey matter in dorsal prefrontal regions. The pathological processes underlying such changes remain unclear and may reflect anomalies in genetic and/or other endogenous mechanisms responsible for brain maturation, the adverse effects of intense or prolonged stress, or other environmental factors. These findings suggest that early markers of impending illness may prove difficult to define, and that brain changes in psychosis may better be conceptualized as anomalous trajectories of brain development. Further, active changes during transition to illness may present the potential to intervene and ameliorate these changes with potential benefit clinically.

Increased prefrontal cerebral blood flow in first-episode schizophrenia following treatment: longitudinal positron emission tomography study

OBJECTIVE

Cognitive deficits, particularly those related to executive function and behavioural control, are a core feature of patients with schizophrenia and implicate disturbances of the prefrontal cortex (PFC). Consistent with this, functional imaging studies have identified abnormalities of PFC activity in chronically affected patients. The objective of the current study was to investigate executive-control related neural activity from first onset of the illness through to symptom stabilization.

METHOD

The authors examined eight neuroleptic-naïve first-episode psychosis (FEP) patients within 3 days of first presentation and eight healthy age- premorbid-IQ, and gender-matched controls (CTL). All FEP patients were later confirmed with a diagnosis of schizophrenia. Subjects underwent H2-15O positron emission tomography (PET) while performing the Stroop interference task that has previously been shown to engage the PFC in healthy samples. In a double-blind paradigm, FEP patients were randomly treated with either haloperidol or risperidone for 8 weeks, after which CTLs and all but one of the FEP patients were re-scanned.

RESULTS

Behaviorally, there was no change in task performance from baseline to follow up for either the FEPs or CTLs. However, there were significant changes in functional activation in both groups across the same period. For CTLs, task-performance was associated with greater recruitment of posterior brain regions at follow up compared to baseline, while for FEP this involved greater recruitment frontal regions. Concurrently, FEP also showed significant improvement in positive symptomatology.

CONCLUSIONS

These findings suggest that disturbances of the PFC often seen in FEP may be, at least partially, associated with acute symptom expression. However, it is still unclear whether this increase in frontal activity is due to symptom stabilization per se, the effects of medication, a lack of neurophysiological 'learning' with experience/practice, or a combination of these factors. In the context of the CTLs performance, we interpret the patient findings as reflective of greater neurophysiological effort required for task accomplishment relative to the learned, more automated, processing apparent in the CTLs.