Verbal and visual memory: characterizing the clinical and intermediate phenotype in schizophrenia

The relationship between gray/white matter contrast and cognitive performance in first-episode schizophrenia

Previous postmortem brain studies have revealed disturbed myelination in the intracortical regions in patients with schizophrenia, possibly reflecting anomalous brain maturational processes. However, it currently remains unclear whether this anomalous myelination is already present in early illness stages and/or progresses during the course of the illness. In this magnetic resonance imaging study, we examined gray/white matter contrast (GWC) as a potential marker of intracortical myelination in 63 first-episode schizophrenia (FESz) patients and 77 healthy controls (HC). Furthermore, we investigated the relationships between GWC findings and clinical/cognitive variables in FESz patients. GWC in the bilateral temporal, parietal, occipital, and insular regions was significantly higher in FESz patients than in HC, which was partly associated with the durations of illness and medication, the onset age, and lower executive and verbal learning performances. Because higher GWC implicates lower myelin in the deeper layers of the cortex, these results suggest that schizophrenia patients have less intracortical myelin at the time of their first psychotic episode, which underlies lower cognitive performance in early illness stages.

A seven-year longitudinal study of the association between neurocognitive function and basic self-disorders in schizophrenia

Introduction

Basic self-disorders (SDs) and neurocognitive impairments are fundamental trait-like aspects of schizophrenia spectrum disorders. There has been little research on the association between SDs and neurocognitive impairments in schizophrenia, and no longitudinal studies have investigated if they are related. The aim of this study was to investigate the association between SDs and neurocognitive function in a follow-up study of patients with schizophrenia.

Methods

SDs and neurocognition were examined in 35 patients with schizophrenia during their first treatment and 7 years later (mean 7.1, SD 0.42). SDs were examined with the Examination of Anomalous Self-Experience (EASE) instrument. The neurocognitive examination included assessments of psychomotor speed, executive- and memory functions.

Results

Poorer executive functions at baseline were significantly associated with more SDs 7 years later and smaller reductions in SDs over time. There were no significant associations between other neurocognitive functions and SDs.

Discussion

Executive functions are important for self-regulation, and impairments in these functions in everyday life may have an impact on the development and/or persistence of SDs.

Low-frequency rTMS treatment alters the topographical organization of functional brain networks in schizophrenia patients with auditory verbal hallucination

Auditory verbal hallucinations (AVH) are an important characteristic of schizophrenia. Repeated transcranial magnetic stimulation (rTMS) has been evidence to be effective in treating AVH. We evaluated the topological properties of resting-state functional brain networks in schizophrenia patients with AVH (n = 32) who received 1-Hz rTMS treatment and matched healthy controls (n = 33). The results showed that the psychotic symptoms and certain neurocognitive performances in patients were improved by rTMS treatment. Furthermore, the pretreatment patients showed abnormal global topological metrics compared with the controls, including lower global efficiency (E_glob, represents the relative quality of information transmission between all nodes in the network) and higher characteristic path length (L_p, characterizes the mean shortest distance between any two nodes in the network). The pretreament patients also showed decreased local topological metrics relative to the controls, including the nodal shortest path (NL_p, quantifies the mean distance between the given node and the other nodes in the network) and nodal efficiency (N_e, measures the information interchange among the neighbor nodes when one node is removed), mainly located in the prefrontal cortex, occipital cortex, and subcortical regions. While the abnormal global and local topological patterns were normalized in patients after rTMS treatment. The multiple linear regression analysis indicated that the baseline topological metrics could be associated with the clinical responses after treatment in the patient group. The results suggested that the topological organization of the functional brain network was globally and regionally altered in schizophrenia patients with AVH after rTMS treatment and may be a potential therapeutic effect for AVH in schizophrenia.

Neurocognitive features, personality traits, and social function in patients with schizophrenia with a history of violence

Recent literature examining associations between cognitive function, clinical features, and violence in patients with schizophrenia has been growing; however, the results are inconsistent. Reports on social function and personality are limited. These studies are yet to be reflected in risk assessment tools and management plans. The aim of this study is to provide a resource for risk assessment and intervention studies by conducting multifaceted well-established assessments in a large population. Data from 355 patients with schizophrenia (112 patients with a history of violence; 243 patients without a history of violence) and 1265 healthy subjects were extracted from a large database of individuals with mental disorders in a general psychiatric population in Japan. The associations between violence in patients with schizophrenia and intellectual function, cognitive function (memory function, executive function, attentional function, verbal learning, processing speed, social cognition), clinical variables, personality traits, social function, and quality of life (QOL) were analyzed. Compared with healthy subjects, the schizophrenia group had broadly impaired cognitive function and social cognition, and their personality traits showed similar differences as those reported previously. Patients with schizophrenia with a history of violence showed significantly more impaired visual memory function (P = 1.9 × 10^-5, Cohen's d = 0.34), longer hospitalization (P = 5.9 × 10^-4, Cohen's d = 0.38), more severe excited factor on Positive and Negative Syndrome Scale (P = 1.6 × 10^-4, Cohen's d = 0.47), higher self-transcendence personality construct on the Temperament and Character Inventory (P = 1.8 × 10^-4, Cohen's d = 0.46), and shorter total working hours per week (P = 4.8 × 10^-4, Cohen's d = 0.53) than those with schizophrenia without a history of violence. New findings, including impaired visual memory, a high self-transcendence personality trait, and shorter total working hours, could be focused on in future interventional research.

Cognitive dysfunction and cortical structural abnormalities in first-episode drug-naïve schizophrenia patients with auditory verbal hallucination

OBJECTIVE

The current study aimed to examine the cognitive profiles and cortical structural alterations in first-episode drug-naïve schizophrenia with AVH (auditory verbal hallucination).

METHODS

Cortical structural parameters including cortical thickness and local gyrification index (LGI) estimated using FreeSurfer as well as cognitive performance assessed on the MATRICS Consensus Cognitive Battery (MCCB) were acquired from 78 schizophrenia patients with AVH, 74 schizophrenia patients without AVH (non-AVH), and 76 healthy controls (HC). Hoffman Auditory Hallucination Rating Scale (HAHRS) was applied to assess the severity of AVH.

RESULTS

The results revealed extensive deficits in all cognitive domains among AVH, non-AVH, and HC groups. Compared to non-AVH group, the AVH group showed poorer performance on visual learning and verbal learning domains. There were six brain regions with cortical thinning in the right hemisphere of inferior temporal gyrus, superior temporal gyrus, lateral orbito frontal cortex, rostral anterior cingulate cortex, supramarginal gyrus and insula, and two brain regions with increased LGI in the left hemisphere of superior parietal gyrus and the right hemisphere of caudal anterior cingulate cortex on AVH group relative to non-AVH group. Correlation analysis revealed that the cortical thickness in the right hemisphere of lateral orbito frontal cortex was negatively correlated with the severity of AVH in schizophrenia patients with AVH.

CONCLUSION

Visual learning, verbal learning dysfunction, and specific disruption of cortical structure may characterize schizophrenia patients with AVH during early stages of the disorder. Right lateral orbito frontal cortical deficits may be the pathological mechanisms underlying AVH in first-episode drug-naïve schizophrenia.

Changes of neurocognitive status in patients with the first-episode psychosis after 18 months of treatment-A prospective cohort study

Neurocognitive symptoms exert the most influence on treatment outcomes over the course of schizophrenia, starting from the first-episode of psychosis (FEP) onwards. Our aim was to analyze the neurocognitive status of FEP compared to healthy controls (HC), and its change after 18 months of treatment. We performed a study in a sample of 159 patients with FEP and 100 HC. We followed the patients up for 18 months after initial assessment with a battery of neurocognitive tests. We observed statistically significant improvement in the majority of neurocognitive tests after 18 months, but several tests of specific neurocognitive domains (verbal memory, language functions, executive functions) did not show significant differences between the two assessments. The results for the majority of tests obtained from patients with FEP after 18 months of treatment showed significant deterioration compared with HC. Although our study showed significant improvement of baseline neurocognitive deficits in FEP with treatment, this varied across domains and overall performance remained below that of HC. Thus, while it seems that treatment of FEP may help to delay or restore neurocognitive deterioration, it is unclear whether specific areas of neurocognitive deterioration (e.g. verbal domain) would benefit from more time or specific treatment approaches.

The association between exposure to herpes simplex virus type 1 (HSV-1) and cognitive functioning in schizophrenia: A meta-analysis

Cognitive deficits are characteristic of schizophrenia but their etiology is not understood. Previous studies show an association between viral exposures and cognitive impairment. This meta-analysis was undertaken to determine the relationship of herpes simplex virus type 1 (HSV-1) exposure and cognitive functioning in schizophrenia. A systematic search was performed for studies comparing the cognitive functioning of HSV-1 seropositive vs. seronegative persons with schizophrenia. The primary outcome was the standardized mean difference (SMD) in composite cognitive score using Hedges' g. Secondary outcomes were SMDs in 9cognitive domains. Study heterogeneity was estimated using the I² index and formal tests of heterogeneity using Cochran's Q. In a sample of 3516 individuals from 9 studies the SMD was negative for the composite score and all 9 domains indicating a significant deficit for seropositive individuals in 8 domains. The SMDs ranged from -0.11 (Working Memory) to -0.36 (Visual Spatial). Cochran's Q test indicated heterogeneity for one domain. The I² index of heterogeneity was in the low -moderate range for all but one domain. Exposure to HSV-1 is associated with decreased cognitive functioning in schizophrenia. An increased understanding of HSV-1 exposure might lead to improved methods for the prevention and treatment of cognitive deficits in schizophrenia.

Neurocan genome-wide psychiatric risk variant affects explicit memory performance and hippocampal function in healthy humans

Alterations of the brain extracellular matrix (ECM) can perturb the structure and function of brain networks like the hippocampus, a key region in human memory that is commonly affected in psychiatric disorders. Here, we investigated the potential effects of a genome-wide psychiatric risk variant in the NCAN gene encoding the ECM proteoglycan neurocan (rs1064395) on memory performance, hippocampal function and cortical morphology in young, healthy volunteers. We assessed verbal memory performance in two cohorts (N = 572, 302) and found reduced recall performance in risk allele (A) carriers across both cohorts. In 117 participants, we performed functional magnetic resonance imaging using a novelty-encoding task with visual scenes. Risk allele carriers showed higher false alarm rates during recognition, accompanied by inefficiently increased left hippocampal activation. To assess effects of rs1064395 on brain morphology, we performed voxel-based morphometry in 420 participants from four independent cohorts and found lower grey matter density in the ventrolateral and rostral prefrontal cortex of risk allele carriers. In silico eQTL analysis revealed that rs1064395 SNP is linked not only to increased prefrontal expression of the NCAN gene itself, but also of the neighbouring HAPLN4 gene, suggesting a more complex effect of the SNP on ECM composition. Our results suggest that the NCAN rs1064395 A allele is associated with lower hippocampus-dependent memory function, variation of prefrontal cortex structure and ECM composition. Considering the well-documented hippocampal and prefrontal dysfunction in bipolar disorder and schizophrenia, our results may reflect an intermediate phenotype by which NCAN rs1064395 contributes to disease risk.

Applying speech technologies to assess verbal memory in patients with serious mental illness

Verbal memory deficits are some of the most profound neurocognitive deficits associated with schizophrenia and serious mental illness in general. As yet, their measurement in clinical settings is limited to traditional tests that allow for limited administrations and require substantial resources to deploy and score. Therefore, we developed a digital ambulatory verbal memory test with automated scoring, and repeated self-administration via smart devices. One hundred and four adults participated, comprising 25 patients with serious mental illness and 79 healthy volunteers. The study design was successful with high quality speech recordings produced to 92% of prompts (Patients: 86%, Healthy: 96%). The story recalls were both transcribed and scored by humans, and scores generated using natural language processing on transcriptions were comparable to human ratings (R = 0.83, within the range of human-to-human correlations of R = 0.73-0.89). A fully automated approach that scored transcripts generated by automatic speech recognition produced comparable and accurate scores (R = 0.82), with very high correlation to scores derived from human transcripts (R = 0.99). This study demonstrates the viability of leveraging speech technologies to facilitate the frequent assessment of verbal memory for clinical monitoring purposes in psychiatry.

Genetic Effects of DISC1 and G72 (DAOA) on Visual Learning of Patients with Schizophrenia

BACKGROUND

Visual learning plays an important role in general populations and patients with schizophrenia. Genetic influences on visual learning remain unknown. Two functional single nucleotide polymorphisms (SNPs), Ser704Cys of the DISC1 gene and M24 (rs1421292) of the G72 gene, are strongly associated with pathogenesis and pathophysiology of schizophrenia. This study examined these two SNPs' effects on visual learning in schizophrenia patients.

METHODS

Two hundred seventy-one patients (mean age, 37.0 years [SD = 9.3]; 159 men) with chronic schizophrenia were genotyped for the DISC1 Ser704Cys and G72 M24 SNPs and assessed for visual learning with Visual Reproduction II (delayed reproduction) of Wechsler Memory Scale - III (WMS-III). For comparison, verbal learning (using Word list II of WMS-III) and attention (by Continuous Performance Test) were also measured.

RESULTS

The DISC1 Ser carriers excelled DISC1 Cys/Cys homozygotes in visual learning (p=0.004, effect size: 0.43), but not in other cognitive functions. G72 M24 A-allele carriers and G72 M24 T/T homozygotes performed similarly (effect size: 0.07). In SNP-SNP interaction analysis, the patients with Ser carrier_T/T had better visual learning than those with Cys/Cys_T/T (p=0.004, effect size: 0.70) and those with Cys/Cys_A-allele carrier (p=0.003, effect size: 0.65). Education had a positive effect (p=0.007), while negative symptoms had a negative effect (p<0.001) on visual learning.

CONCLUSION

The findings suggest that genetic variations in DISC1 Ser704Cys and G72 M24 affect visual learning in schizophrenia patients. The effect sizes of SNP-SNP interaction surpassed the sum (0.50) of effect sizes from two individual genes, suggesting synergistic DISC1-G72 interaction.

Altered Brain Activation During Memory Retrieval Precedes and Predicts Conversion to Psychosis in Individuals at Clinical High Risk

Memory deficits are a hallmark of psychotic disorders such as schizophrenia. However, whether the neural dysfunction underlying these deficits is present before the onset of illness and potentially predicts conversion to psychosis is unclear. In this study, we investigated brain functional alterations during memory processing in a sample of 155 individuals at clinical high risk (including 18 subjects who later converted to full psychosis) and 108 healthy controls drawn from the second phase of the North American Prodrome Longitudinal Study (NAPLS-2). All participants underwent functional magnetic resonance imaging with a paired-associate memory paradigm at the point of recruitment and were clinically followed up for approximately 2 years. We found that at baseline, subjects at high risk showed significantly higher activation during memory retrieval in the prefrontal, parietal, and bilateral temporal cortices (PFWE < .035). This effect was more pronounced in converters than nonconverters and was particularly manifested in unmedicated subjects (P < .001). The hyperactivation was significantly correlated with retrieval reaction time during scan in converters (P = .009) but not in nonconverters and controls, suggesting an exaggerated retrieval effort. These findings suggest that hyperactivation during memory retrieval may mark processes associated with conversion to psychosis, and such measures have potential as biomarkers for psychosis prediction.

Nrg1 deficiency modulates the behavioural effects of prenatal stress in mice

Little is known about the exact genes that confer vulnerability or resilience to environmental stressors during early neurodevelopment. Partial genetic deletion of neuregulin 1 (Nrg1) moderates the neurobehavioural effects of stressors applied in adolescence and adulthood, however, no study has yet examined its impact on prenatal stress. Here we examined whether Nrg1 deficiency in mice modulated the impact of prenatal stress on various behaviours in adulthood. Male heterozygous Nrg1 mice were mated with wild-type female mice who then underwent daily restraint stress from days 13 to 19 of gestation. Surprisingly, prenatal stress had overall beneficial effects by facilitating sensorimotor gating, increasing sociability, decreasing depressive-like behaviour, and improving spatial memory in adulthood. Such benefits were not due to any increase in maternal care, as prenatal stress decreased nurturing of the offspring. Nrg1 deficiency negated the beneficial behavioural effects of prenatal stress on all measures except sociability. However, Nrg1 deficiency interacted with prenatal stress to trigger locomotor hyperactivity. Nrg1 deficiency, prenatal stress or their combination failed to alter acute stress-induced plasma corticosterone concentrations. Collectively these results demonstrate that Nrg1 deficiency moderates the effects of prenatal stress on adult behaviour, but it does so in a complex, domain-specific fashion.

Associative Memory Impairments Are Associated With Functional Alterations Within the Memory Network in Schizophrenia Patients and Their Unaffected First-Degree Relatives: An fMRI Study

Memory impairments are a major characteristic of schizophrenia (SZ). In the current study, we used an associative memory task to test the hypothesis that SZ patients and first-degree relatives have altered functional patterns in comparison to healthy controls. We analyzed the fMRI activation pattern during the presentation of a face-name task in 27 SZ patients, 23 first-degree relatives, and 27 healthy controls. In addition, we performed correlation analyses between individual psychopathology, accuracy and reaction time of the task and the beta scores of the functional brain activations. We observed a lower response accuracy and increased reaction time during the retrieval of face-name pairs in SZ patients compared with controls. Deficient performance was accompanied by abnormal functional activation patterns predominantly in DMN regions during encoding and retrieval. No significant correlation between individual psychopathology and neuronal activation during encoding or retrieval of face-name pairs was observed. Findings of first-degree relatives indicated slightly different functional pattern within brain networks in contrast to controls without significant differences in the behavioral task. Both the accuracy of memory performance as well as the functional activation pattern during retrieval revealed alterations in SZ patients, and, to a lesser degree, in relatives. The results are of potential relevance for integration within a comprehensive model of memory function in SZ. The development of a neurophysiological model of cognition in psychosis may help to clarify and improve therapeutic options to improve memory and functioning in the illness.

Cognitive deficit in patients with paranoid schizophrenia: Its clinical and laboratory correlates

The aim of this study was to search for correlates of cognitive impairment in patients with paranoid schizophrenia among clinical, demographic, anamnestic and biochemical markers (NSE, S100B protein, BDNF, hs-CRP). Patients with paranoid schizophrenia (n=125) were examined using the Brief Assessment of Cognitive Function in Schizophrenia, the Rey-Osterrieth Complex Figure task, and a number of clinical scales including the Positive and Negative Syndrome Scale. The majority of patients demonstrated cognitive impairment. The type of impairment was highly heterogeneous and individual. Relationships were found between the degree of executive functioning and family history of mental illness; working memory and age of onset of schizophrenia; and visual memory and psychopathological symptomatology. Negative and affective symptoms were not significantly associated with cognitive functioning. Treatment with first generation antipsychotics was associated with a more frequent impairment of motor skills, and concomitant anticholinergic drugs, with reduced accuracy. Use of second-generation antipsychotics only was associated with better accuracy, working memory and speech fluency. Among the patients, 21.4% had signs of a systemic inflammatory response, indicating a possible role of inflammatory response in the development of schizophrenia. CRP, S100B and NSE levels reflected features of the course of illness and therapeutic response. Patients with lower concentrations of BDNF were characterized by lower processing speeds.

Greater extracellular free-water in first-episode psychosis predicts better neurocognitive functioning

Free Water Imaging is a novel diffusion magnetic resonance (MR) imaging method that is able to separate changes affecting the extracellular space from those that reflect changes in neuronal cells and processes. A previous Free Water Imaging study in schizophrenia identified significantly greater extracellular water volume in the early stages of the disorder; however, its clinical and functional sequelae have not yet been investigated. Here, we applied Free Water Imaging to a larger cohort of 63 first-episode patients with psychosis and 70 healthy matched controls to better understand the functional significance of greater extracellular water. We used diffusion MR imaging data and the Tract-Based Spatial Statistics analytic pipeline to first analyze fractional anisotropy (FA), the most commonly employed metric for assessing white matter. This comparison was then followed by Free Water Imaging analysis, where two parameters, the fractional volume of extracellular free-water (FW) and cellular tissue FA (FA-t), were estimated and compared across the entire white matter skeleton between groups, and correlated with cognitive measures at baseline and following 12 weeks of antipsychotic treatment. Our results indicated lower FA across the whole brain in patients compared with healthy controls that overlap with significant increases in FW, with only limited decreases in FA-t. In addition, higher FW correlated with better neurocognitive functioning following 12 weeks of antipsychotic treatment. We believe this is the first study to suggest that an extracellular water increase during the first-episode of psychosis, which may be indicative of an acute neuroinflammatory process, and/or cerebral edema may predict better functional outcome.

Exercise Treatments for Psychosis: A Review

Schizophrenia is a devastating mental illness that has profound effects on a person's health and quality of life. Exercise represents a promising new treatment option that may supplement current psychosocial and pharmacological interventions for psychosis. A large body of work suggests that exercise can improve cardio-metabolic and health behavior and facilitate neurogenesis in areas of the brain that are notably impacted by psychosis. Recent efforts to incorporate exercise as either stand-alone or adjunctive treatment for individuals with schizophrenia range from yoga and light stretching to moderately intense walking, bike riding, or team sports. These interventions suggest that moderately intense exercise may be beneficial for improving both positive and negative symptomatology, cognition and functioning. Indeed, exercise may be beneficial for decreasing risk factors for a wide range of health problems often observed in patients with schizophrenia, including weight gain and metabolic syndrome as well as tobacco and substance use. Given the positive results from interventions in schizophrenia patients, there is an impetus for incorporating exercise in the early stages of the disorder. Notably, individuals at ultrahigh risk (UHR) for psychosis report more sedentary behavior and perceive less benefit from exercise; interventions prior to the onset of the disorder may be helpful for increasing health behaviors, perhaps delaying or preventing the onset of psychosis. Taken together, for individuals with psychosis, exercise may provide holistic benefits for the neural to the social impairments.

D-cycloserine in Schizophrenia: New Strategies for Improving Clinical Outcomes by Enhancing Plasticity

Background

Dysregulation of N-methyl D-aspartate (NMDA) receptor signaling is strongly implicated in schizophrenia. Based on the ketamine model of NMDA receptor hypoactivity, therapeutic approaches designed to maintain a sustained increase in agonist activity at the glycine site of the NMDA receptor have produced promising, although inconsistent, efficacy for negative symptoms.

Methods

A review of the published literature on D-cycloserine (DCS) pharmacology in animal models and in clinical studies was performed. Findings relevant to DCS effects on memory and plasticity and their potential clinical application to schizophrenia were summarized.

Results

Studies in animals and clinical trials in patients with anxiety disorders have demonstrated that single or intermittent dosing with DCS enhances memory consolidation. Preliminary trials in patients with schizophrenia suggest that intermittent dosing with DCS may produce persistent improvement of negative symptoms and enhance learning when combined with cognitive behavioral therapy for delusions or with cognitive remediation. The pharmacology of DCS is complex, since it acts as a “super agonist” at NMDA receptors containing GluN2C subunits and, under certain conditions, it may act as an antagonist at NMDA receptors containing GluN2B subunits.

Conclusions

There are preliminary findings that support a role for D-cycloserine in schizophrenia as a strategy to enhance neuroplasticity and memory. However, additional studies with DCS are needed to confirm these findings. In addition, clinical trials with positive and negative allosteric modulators with greater specificity for NMDA receptor subtypes are needed to identify the optimal strategy for enhancing neuroplasticity in schizophrenia.

Visual working memory deterioration preceding relapse in psychosis

BACKGROUND

Relapse is distressingly common after the first episode of psychosis, yet it is poorly understood and difficult to predict. Investigating changes in cognitive function preceding relapse may provide new insights into the underlying mechanism of relapse in psychosis. We hypothesized that relapse in fully remitted first-episode psychosis patients was preceded by working memory deterioration.

METHOD

Visual memory and verbal working memory were monitored prospectively in a 1-year randomized controlled trial of remitted first-episode psychosis patients assigned to medication continuation (quetiapine 400 mg/day) or discontinuation (placebo). Relapse (recurrence of positive symptoms of psychosis), visual (Visual Patterns Test) and verbal (Letter-Number span test) working memory and stressful life events were assessed monthly.

RESULTS

Remitted first-episode patients (n = 102) participated in the study. Relapsers (n = 53) and non-relapsers (n = 49) had similar baseline demographic and clinical profiles. Logistic regression analyses indicated relapse was associated with visual working memory deterioration 2 months before relapse [odds ratio (OR) 3.07, 95% confidence interval (CI) 1.19-7.92, P = 0.02], more stressful life events 1 month before relapse (OR 2.11, 95% CI 1.20-3.72, P = 0.01) and medication discontinuation (OR 5.52, 95% CI 2.08-14.62, P = 0.001).

CONCLUSIONS

Visual working memory deterioration beginning 2 months before relapse in remitted first-episode psychosis patients (not baseline predictor) may reflect early brain dysfunction that heralds a psychotic relapse. The deterioration was found to be unrelated to a worsening of psychotic symptoms preceding relapse. Testable predictors offer insight into the brain processes underlying relapse in psychosis.

Temporal perception deficits in schizophrenia: integration is the problem, not deployment of attentions

Patients with schizophrenia are known to have impairments in sensory processing. In order to understand the specific temporal perception deficits of schizophrenia, we investigated and determined to what extent impairments in temporal integration can be dissociated from attention deployment using Attentional Blink (AB). Our findings showed that there was no evident deficit in the deployment of attention in patients with schizophrenia. However, patients showed an increased temporal integration deficit within a hundred-millisecond timescale. The degree of such integration dysfunction was correlated with the clinical manifestations of schizophrenia. There was no difference between individuals with/without schizotypal personality disorder in temporal integration. Differently from previous studies using the AB, we did not find a significant impairment in deployment of attention in schizophrenia. Instead, we used both theoretical and empirical approaches to show that previous findings (using the suppression ratio to correct for the baseline difference) produced a systematic exaggeration of the attention deficits. Instead, we modulated the perceptual difficulty of the task to bring the baseline levels of target detection between the groups into closer alignment. We found that the integration dysfunction rather than deployment of attention is clinically relevant, and thus should be an additional focus of research in schizophrenia.

Prospective memory performance in non-psychotic first-degree relatives of patients with schizophrenia: a controlled study

Objective

We aimed at investigating prospective memory and its socio-demographic and neurocognitive correlates in non-psychotic, first-degree relatives (FDRs) of patients with schizophrenia compared to patients with first episode schizophrenia (FES), and healthy controls (HCs).

Methods

Forty-seven FES patients, 50 non-psychotic FDRs (23 offspring and 27 siblings) of patients with chronic schizophrenia (unrelated to the FES group) and 51 HCs were studied. The Chinese version of the Cambridge Prospective Memory Test (C-CAMPROMPT) was used to measure time-based prospective memory (TBPM) and event-based prospective memory (EBPM) performance. Other cognitive functions (involving respective memory and executive functions) were evaluated with standardized tests.

Results

After controlling for basic demographic characteristics including age, gender and educational level, there was a significant difference between FDRs, FES and HCs with respect to both TBPM (F_(2,142) = 10.4, p<0.001) and EBPM (F_(2,142) = 10.8, p<0.001). Multiple linear regression analyses revealed that lower scores of the Hopkins Verbal Learning Test-Revised (HVLT-R) and the STROOP Word-Color Test (SWCT) contributed to TBPM impairment, while lower educational level and higher scores of the Color Trails Test-2 (CTT-2) contributed to EBPM deficit in FDRs.

Conclusions

FDRs share similar but attenuated prospective memory impairments with schizophrenia patients, suggesting that prospective memory deficits may represent an endophenotype of schizophrenia.

Executive functioning and psychopathological profile in relatives of individuals with deficit v. non-deficit schizophrenia: a pilot study

Aims. Heterogeneity of schizophrenia is known to be reflected in neuropsychological functioning of patients, but its expression in relatives is understudied. This study aims at exploring relationship between executive functioning and clinical profiles of first-degree relatives of patients who are classified as having or not having the deficit subtype of schizophrenia (DSRELs v. non-DSRELs), with the prediction of greater executive impairment in DSRELs. Methods. DSRELs (n = 15) and non-DSRELs (n = 40) were compared with community controls (CCs, n = 55) on executive functioning measured by the Wisconsin Card Sorting Test (WCST) and the phonemic verbal fluency (PVF), and clinical measures. Effects of psychopathology and intelligence quotient (IQ) measures were investigated to determine their association with executive performance. Results. DSRELs showed more executive dysfunction on WCST and poorer social functioning than CCs and more severe negative symptoms than non-DSRELs. Differences on WCST-categories achieved (WCST-CA) remained significant after adjustment for clinical confounders and IQ. WCST-CA was associated with apathy and paranoid ideation only within the DSREL subgroup. Conclusions. Executive functioning and negative symptoms are severely impaired in first-degree relatives of deficit syndrome patients, thus suggesting that some neurocognitive deficits in patients may be transmitted within families according to the pathophysiology of the probands.

A computational language approach to modeling prose recall in schizophrenia

Many cortical disorders are associated with memory problems. In schizophrenia, verbal memory deficits are a hallmark feature. However, the exact nature of this deficit remains elusive. Modeling aspects of language features used in memory recall have the potential to provide means for measuring these verbal processes. We employ computational language approaches to assess time-varying semantic and sequential properties of prose recall at various retrieval intervals (immediate, 30 min and 24 h later) in patients with schizophrenia, unaffected siblings and healthy unrelated control participants. First, we model the recall data to quantify the degradation of performance with increasing retrieval interval and the effect of diagnosis (i.e., group membership) on performance. Next we model the human scoring of recall performance using an n-gram language sequence technique, and then with a semantic feature based on Latent Semantic Analysis. These models show that automated analyses of the recalls can produce scores that accurately mimic human scoring. The final analysis addresses the validity of this approach by ascertaining the ability to predict group membership from models built on the two classes of language features. Taken individually, the semantic feature is most predictive, while a model combining the features improves accuracy of group membership prediction slightly above the semantic feature alone as well as over the human rating approach. We discuss the implications for cognitive neuroscience of such a computational approach in exploring the mechanisms of prose recall.

Verbal memory impairment in healthy siblings of patients with schizophrenia

Cognitive deficits have been recognized as a core feature of schizophrenia (SZ) and are present in most patients. Verbal memory (VM), working memory (WM), and executive function (EF) are domains commonly impaired in patients with SZ. These latter domains have been related to the genetic risk of the disorder characterizing as possible endophenotypes. In order to study neurocognitive endophenotypes in a Brazilian population with elevated genetic risks to develop SZ, we measured VM (Hopkins Verbal Learning Test Revised), WM (Letter-Number Sequencing and Digit Span) and EF (Stroop Test) in 90 subjects (45 unaffected siblings of patients with SZ and 45 matched healthy controls). No differences were found in EF and WM (Letter-Number Sequencing and Digit Span). However, in VM, siblings of patients performed worse than controls on the immediate recall and delayed recall. Our results suggest that VM impairment could be considered an endophenotype of SZ.

Ten year neurocognitive trajectories in first-episode psychosis

Objective: Neurocognitive impairment is commonly reported at onset of psychotic disorders. However, the long-term neurocognitive course remains largely uninvestigated in first episode psychosis (FEP) and the relationship to clinically significant subgroups even more so. We report 10 year longitudinal neurocognitive development in a sample of FEP patients, and explore whether the trajectories of cognitive course are related to presence of relapse to psychosis, especially within the first year, with a focus on the course of verbal memory.

Method: Forty-three FEP subjects (51% male, 28 ± 9 years) were followed-up neurocognitively over five assessments spanning 10 years. The test battery was divided into four neurocognitive indices; Executive Function, Verbal Learning, Motor Speed, and Verbal Fluency. The sample was grouped into those relapsing or not within the first, second and fifth year.

Results: The four neurocognitive indices showed overall stability over the 10 year period. Significant relapse by index interactions were found for all indices except Executive Function. Follow-up analyses identified a larger significant decrease over time for the encoding measure within Verbal Memory for patients with psychotic relapse in the first year [F_{(4, 38)} = 5.8, p = 0.001, η² = 0.40].

Conclusions: Main findings are long-term stability in neurocognitive functioning in FEP patients, with the exception of verbal memory in patients with psychotic relapse or non-remission early in the course of illness. We conclude that worsening of specific parts of cognitive function may be expected for patients with on-going psychosis, but that the majority of patients do not show significant change in cognitive performance during the first 10 years after being diagnosed.

Discrimination within Recognition Memory in Schizophrenia

Episodic memory is one of the most affected cognitive domains in schizophrenia. First-degree biological relatives of individuals with schizophrenia also have been found to exhibit a similar, but milder, episodic memory deficit. Unlike most studies that focus on the percent of previously presented items recognized, the current investigation sought to further elucidate the nature of memory dysfunction associated with schizophrenia by examining the discrimination of old and new material during recognition (measured by d') to consider false recognition of new items. Using the Recurring Figures Test and the California Verbal Learning Test (CVLT), we studied a sample of schizophrenia probands and the first-degree biological relatives of patients with schizophrenia, as well as probands with bipolar disorder and first-degree biological relatives to assess the specificity of recognition memory dysfunction to schizophrenia. The schizophrenia sample had poorer recognition discrimination in both nonverbal and verbal modalities; no such deficits were identified in first-degree biological relatives or bipolar disorder probands. Discrimination in schizophrenia and bipolar probands failed to benefit from the geometric structure in the designs in the manner that controls did on the nonverbal test. Females performed better than males in recognition of geometric designs. Episodic memory dysfunction in schizophrenia is present for a variety of stimulus domains and reflects poor use of item content to increase discrimination of old and new items.

Verbal and visual-spatial memory impairment in youth at familial risk for schizophrenia or affective psychosis: a pilot study

BACKGROUND

Schizophrenia and affective psychoses share several common biological origins, particularly genetic susceptibility. Kraepelin posited that differing clinical expressions in these disorders reflect different etiopathologies. We tested a neuropsychological component of this hypothesis by evaluating verbal memory and visual memory performance in nonpsychotic youth at familial risk for psychosis, taking into account contributions to memory dysfunction including executive processing and psychopathology.

METHODS

Teenage and young adults (ages 13-25) at familial high-risk (FHR) for schizophrenia (HR-SCZ, n=41) or affective psychosis (HR-AFF, n=24) were compared to community controls (CC, n=54) on verbal (Miller-Selfridge Context Memory) and visual (Rey-Osterrieth Complex Figure) memory tests in which the roles of strategy and contextual processing on distinct recall domains could be assessed. Effects of psychopathology, vigilance and working memory were investigated to determine their influence on memory performance.

RESULTS

HR-AFF and HR-SCZ exhibited similarly impaired memory profiles and elevated levels of psychopathology compared to CC. HR-SCZ were significantly impaired on both verbal memory and visual-spatial memory, while HR-AFF in verbal memory only. However, effect sizes, in the medium range, were largely comparable between the two HR groups. Deficits in verbal recall and in visual memory organization remained significant after adjustment for confounders.

CONCLUSIONS

Youth at FHR for psychosis present relatively common memory deficits across both visual-spatial and verbal modalities that are not explained by current psychopathology, vigilance or working memory deficits. Deficits in organizing information to be recalled represent a promising trait of psychosis vulnerability.

A protective-compensatory model may reconcile the genetic and the developmental findings in schizophrenia

OBJECTIVE

The neurodevelopmental, the multifactorial-oligogenic and the gene-environment diathesis models have provoked advances in schizophrenia research, yet the exact pathophysiology remains indefinable. We broadened our analysis of 20years of findings in adults and children descending from densely affected families in the Québec population with a founder effect. The goal was to inspect the link between these family-genetic and developmental findings.

METHOD

48 multigenerational families affected by schizophrenia or bipolar disorder represented a quasi-total sample of affected kindreds in the Eastern-Quebec catchment area. Among the 1274 adult family members with lifetime best-estimate diagnoses, 341 had DSM-IV schizophrenia or bipolar disorder. Young offspring of an affected parent were studied with the same clinical, physiological and cognitive measures as the adults.

RESULTS

Four new observations emerged: 1. A striking resemblance between the clinical, neuropsychological and genetic findings in these densely affected families and those reported in sporadic samples; 2. A high degree of heterogeneity despite the origin from a founder-effect population; 3. Cognitive deficits in some non-affected adult relatives as severe as those in patients; 4. Children descending from kindreds displayed neurodevelopmental endophenotypic anomalies comparable to those of adult patients.

CONCLUSION

These four observations could be reconciled under the hypothesis that highly familial and sporadic cases share mechanisms based on defective protective genes, a model to an extent similar to cancer findings. These defective protective genes running in families would longitudinally disturb the compensatory mechanisms in children inheriting them and might be at the core of the schizophrenia process.

The AKT1 gene is associated with attention and brain morphology in schizophrenia

OBJECTIVES

A meta-analysis of the associations between genetic variants in the AKT1 gene and schizophrenia found that a single nucleotide polymorphism (SNP5; rs2494732) was associated with schizophrenia in Asian populations.

METHODS

In this study, we investigated the effects of this SNP on memory and attentional performance and brain structure using magnetic resonance imaging in a Japanese population (117 patients with schizophrenia and 189 healthy subjects).

RESULTS

The memory performance, particularly attention/concentration score, measured by the Wechsler Memory Scale-Revised in A carriers of SNP5, which was found to be enriched in patients with schizophrenia, was lower than that in individuals with the G/G genotype. We confirmed the association of the SNP with attentional performance using the Continuous Performance Test, which assessed sustained attention and vigilance of attentional function. Patients with A allele demonstrated lower attentional performance than patients with the G/G genotype. Patients with the A allele had smaller gray matter volumes in the right inferior parietal lobule related to attentional processes and in the frontostriatal region related to different SNPs in AKT1 than patients with the G/G genotype.

CONCLUSIONS

Our results suggest that a genetic variant of AKT1 might be associated with attentional deficits and brain morphological vulnerability in patients with schizophrenia.

Promoter polymorphisms in two overlapping 6p25 genes implicate mitochondrial proteins in cognitive deficit in schizophrenia

In a previous study, we detected a 6p25-p24 region linked to schizophrenia in families with high composite cognitive deficit (CD) scores, a quantitative trait integrating multiple cognitive measures. Association mapping of a 10 Mb interval identified a 260 kb region with a cluster of single-nucleotide polymorphisms (SNPs) significantly associated with CD scores and memory performance. The region contains two colocalising genes, LYRM4 and FARS2, both encoding mitochondrial proteins. The two tagging SNPs with strongest evidence of association were located around the overlapping putative promoters, with rs2224391 predicted to alter a transcription factor binding site (TFBS). Sequencing the promoter region identified 22 SNPs, many predicted to affect TFBSs, in a tight linkage disequilibrium block. Luciferase reporter assays confirmed promoter activity in the predicted promoter region, and demonstrated marked downregulation of expression in the LYRM4 direction under the haplotype comprising the minor alleles of promoter SNPs, which however is not driven by rs2224391. Experimental evidence from LYRM4 expression in lymphoblasts, gel-shift assays and modelling of DNA breathing dynamics pointed to two adjacent promoter SNPs, rs7752203-rs4141761, as the functional variants affecting expression. Their C-G alleles were associated with higher transcriptional activity and preferential binding of nuclear proteins, whereas the G-A combination had opposite effects and was associated with poor memory and high CD scores. LYRM4 is a eukaryote-specific component of the mitochondrial biogenesis of Fe-S clusters, essential cofactors in multiple processes, including oxidative phosphorylation. LYRM4 downregulation may be one of the mechanisms involved in inefficient oxidative phosphorylation and oxidative stress, increasingly recognised as contributors to schizophrenia pathogenesis.

Epistatic interactions of AKT1 on human medial temporal lobe biology and pharmacogenetic implications

AKT1 controls important processes in medial temporal lobe (MTL) development and plasticity, but the impact of human genetic variation in AKT1 on these processes is not known in healthy or disease states. Here, we report that an AKT1 variant (rs1130233) previously associated with AKT1 protein expression, prefrontal function and schizophrenia, affects human MTL structure and memory function. Further, supporting AKT1's role in transducing hippocampal neuroplasticity and dopaminergic processes, we found epistasis with functional polymorphisms in BDNF and COMT--genes also implicated in MTL biology related to AKT1. Consistent with prior predictions that these biologic processes relate to schizophrenia, we found epistasis between the same AKT1, BDNF and COMT functional variants on schizophrenia risk, and pharmacogenetic interactions of AKT1 with the effects on cognition and brain volume measures by AKT1 activators in common clinical use--lithium and sodium valproate. Our findings suggest that AKT1 affects risk for schizophrenia and accompanying cognitive deficits, at least in part through specific genetic interactions related to brain neuroplasticity and development, and that these AKT1 effects may be pharmacologically modulated in patients.

Brain activation patterns during visual episodic memory processing among first-degree relatives of schizophrenia subjects

Episodic memory deficits are proposed as a potential intermediate phenotype of schizophrenia. We examined deficits in visual episodic memory and associated brain activation differences among early course schizophrenia (n=22), first-degree relatives (n=16) and healthy controls without personal or family history of psychotic disorders (n=28). Study participants underwent functional magnetic resonance imaging on a 3T scanner while performing visual episodic memory encoding and retrieval task. We examined in-scanner behavioral performance evaluating response time and accuracy of performance. Whole-brain BOLD response differences were analyzed using SPM5 correcting for multiple comparisons. There was an incremental increase in response time among the study groups (healthy controls<first-degree relatives<schizophrenia) with no differences in accuracy for encoding. Response time for retrieval was significantly increased in schizophrenia subjects compared to healthy controls with no difference in accuracy. Although there were no significant differences in BOLD responses for the encoding task, we noted increased BOLD response to retrieval in the prefrontal regions (Brodmann areas 9 and 8), thalamus and insula among the schizophrenia subjects compared to healthy controls, and first-degree relatives. Familial risk for schizophrenia may be associated with qualitatively similar but quantitatively milder abnormalities in visual episodic memory retrieval but not for encoding in the prefrontal cortex and thalamus.

Do the same factors predict outcome in schizophrenia and non-schizophrenia syndromes after first-episode psychosis? A two-year follow-up study

OBJECTIVE

The aim of this two-year longitudinal study was to identify the best baseline predictors of functional outcome in first-episode psychosis (FEP). We tested whether the same factors predict functional outcomes in two different subsamples of FEP patients: schizophrenia and non-schizophrenia syndrome groups.

METHODS

Ninety-five patients with FEP underwent a full clinical evaluation (i.e., PANSS, Mania, Depression and Insight). Functional outcome measurements included the WHO Disability Assessment Schedule (DAS-WHO), Global Assessment of Functioning (GAF) and Clinical Global Impression (CGI). Estimation of cognition was obtained by a neuropsychological battery which included attention, processing speed, language, memory and executive functioning.

RESULTS

Greater severity of visuospatial functioning at baseline predicted poorer functional outcome as measured by the three functional scales (GAF, CGI and DAS-WHO) in the pooled FEP sample (explaining ut to the 12%, 9% and 10% of the variance, respectively). Negative symptoms also effectively contributed to predict GAF scores (8%). However, we obtained different predictive values after differentiating sample diagnoses. Processing speed significantly predicted most functional outcome measures in patients with schizophrenia, whereas visuospatial functioning was the only significant predictor of functional outcomes in the non-schizophrenia subgroup.

CONCLUSIONS

Our results suggest that processing speed, visuospatial functioning and negative symptoms significantly (but differentially) predict outcomes in patients with FEP, depending on their clinical progression. For patients without a schizophrenia diagnosis, visuospatial functioning was the best predictor of functional outcome. The performance on processing speed seemed to be a key factor in more severe syndromes. However, only a small proportion of the variance could be explained by the model, so there must be many other factors that have to be considered.

The impact of familial risk for schizophrenia or bipolar disorder on cognitive control during episodic memory retrieval

Episodic memory impairment is a robust correlate of familial risk for schizophrenia (SZ) and bipolar disorder (BD); still much is unknown about the processes that underlie this deficit and how they may be implicated in BD and SZ. We examined the possibility that (a) episodic memory impairment may arise from abnormalities in the cognitive control of interference between task-relevant and task-irrelevant memories during retrieval; inability to suppress task-irrelevant representations could give rise to intrusions of inappropriate memories and increased rate of forgetting, (b) cognitive control deficits during retrieval may be differentially affected by familial predisposition to SZ or BD. We examined episodic memory in relatives of patients with SZ (SZ-R) (n=15) or BD (BD-R) (n=17) compared to healthy controls (n=23) using the California Verbal Learning Test (CVLT) and the Doors and People Test (DPT). All relatives were free of any psychiatric morbidity and were matched to controls on age, sex, educational achievement and general intellectual ability. During the CVLT, both relatives' groups made significantly more perseverative recall errors than controls. However, intrusion errors were significantly increased in SZ-R only. SZ-R also showed increased rate of forgetting in the DPT while BD-R were comparable to controls. Familial predisposition to SZ, compared to that of BD, was associated with significantly greater impairment in cognitive control processes during episodic memory retrieval with some evidence of specificity for SZ in connection with mechanisms relating to increased forgetting.

Impaired visual cortical plasticity in schizophrenia

BACKGROUND

Impaired cortical plasticity may be part of the core pathophysiology of schizophrenia (SZ). Long-term potentiation is a form of neuroplasticity that has been recently demonstrated in humans by showing that repetitive visual stimulation produces lasting enhancement of visual evoked potentials (VEP). Using this paradigm, we examined whether visual cortical plasticity is impaired in SZ.

METHODS

Electroencephalographic data were recorded from 19 SZ and 22 healthy control (HC) subjects during a visual long-term potentiation paradigm. Visual evoked potentials were elicited by standard visual stimuli (∼.83 Hz, 2-minute blocks) at baseline and at 2, 4, and 20 minutes following exposure to visual high-frequency stimulation (HFS) (∼8.8 Hz, 2 minutes) designed to induce VEP potentiation. To ensure attentiveness during VEP assessments, subjects responded with a button press to infrequent (10%) target stimuli. Visual evoked potentials were subjected to principal components analysis. Two negative-voltage components prominent over occipital-parietal electrode sites were evident at 92 msec (C1) and at 146 msec (N1b). Changes in C1 and N1b component scores from baseline to the post-HFS assessments were compared between groups.

RESULTS

High-frequency stimulation produced sustained potentiation of visual C1 and N1b in HCs but not in SZs. The HCs and SZs had comparable HFS-driven electroencephalographic visual steady state responses. However, greater visual steady state responses to the HFS predicted greater N1b potentiation in HCs but not in SZs. Schizophrenia patients with greater N1b potentiation decreased their reaction times to target stimuli.

CONCLUSIONS

Visual cortical plasticity is impaired in schizophrenia, consistent with hypothesized deficits in N-methyl-D-aspartate receptor function.

The association between self-disorders and neurocognitive dysfunction in schizophrenia

BACKGROUND

Neurocognitive deficits and self-disorders (i.e. altered basic self-awareness or - sense of self) have both been suggested as fundamental trait features of schizophrenia. However, no study until now has investigated the relationship between these two core features.

AIM

To investigate the relationship between self-disorders and neurocognitive performance in patients with schizophrenia.

METHOD

Self-disorders were assessed in 57 patients in the early phase of schizophrenia by means of the Examination of Anomalous Self-Experience (EASE) instrument. The neurocognitive assessments included measures of psychomotor speed, working memory, executive- and memory functions.

RESULTS

There were few associations between self-disorders and neurocognitive impairments. However, high levels of SDs were significantly associated with impaired verbal memory.

CONCLUSION

The reason for the general lack of associations between self-disorders and neurocognition could be that they represent different basic features of the illness. Verbal memory may however be linked to deficits in the patients' ability to comprehend, direct, remember and reason about their thoughts, functions that are intimately related to the basic sense of self.

Metaphor interpretation and use: a window into semantics in schizophrenia

The nature of putative semantic anomalies in schizophrenia is controversial. Metaphor interpretation and use provide a useful methodology with which to probe semantics since metaphors are critical in reasoning processes and in how conceptual knowledge is organized. The first study examined free speech for figurative language. The second study explored whether emotional versus non-emotional metaphorical language interpretation elicits differences in the tendencies to produce idiosyncratic (bizarre) or literal interpretations or use of other metaphors to describe the meaning of a metaphor. The third study examined the interpretation of time metaphors. We expected the time perspective in ambiguous sentences to be differentially influenced by previously presented unambiguous sentences of a specific perspective, either events moving relative to a stationary observer (moving-time) or an observer moving relative to a stationary event (moving-ego). First, we found that patients used a similar amount of figurative language as control participants. Second, we did not find any difference between the groups in terms of idiosyncratic interpretations, although patients did interpret more metaphors literally and controls utilized more figurative language. Third, we did not find evidence of a difference between the groups in terms of time perspectives influencing ambiguous target sentences differentially. As operationalized here, the interpretation and use of metaphors is similar in patients with schizophrenia to that of healthy control participants. To the extent that metaphors recruit semantic processes this area of cognition is generally intact in schizophrenia.

Verbal and visual memory impairments among young offspring and healthy adult relatives of patients with schizophrenia and bipolar disorder: selective generational patterns indicate different developmental trajectories

OBJECTIVE

Memory deficits have been shown in patients affected by schizophrenia (SZ) and bipolar (BP)/mood disorder. We recently reported that young high-risk offspring of an affected parent were impaired in both verbal episodic memory (VEM) and visual episodic memory (VisEM). Understanding better the trajectory of memory impairments from childhood to adult clinical status in risk populations is crucial for early detection and prevention. In multigenerational families densely affected by SZ or BP, our aim was to compare the memory impairments observed in young nonaffected offspring with memory functioning in nonaffected adult relatives and patients.

METHODS

For 20 years, we followed up numerous kindreds in the Eastern Québec population. After having characterized the Diagnostic and Statistical Manual of Mental Disorders phenotypes, we assessed cognition (N = 381) in 3 subsamples in these kindreds and in controls: 60 young offspring of a parent affected by SZ or BP, and in the adult generations, 92 nonaffected adult relatives and 40 patients affected by SZ or BP. VEM was assessed with the California Verbal Learning Test and VisEM with the Rey figures.

RESULTS

The VEM deficits observed in the offspring were also found in adult relatives and patients. In contrast, the VisEM impairments observed in the young offspring were present only in patients, not in the adult relatives.

CONCLUSION

Implications for prevention and genetic mechanisms can be drawn from the observation that VEM and VisEM would show distinct generational trajectories and that the trajectory associated with VisEM may offer a better potential than VEM to predict future risk of developing the disease.

Comparison between young siblings and offspring of subjects with schizophrenia: clinical and neuropsychological characteristics

INTRODUCTION

High rates of psychopathology and worse performance in cognitive areas have been described in high risk (HR) first degree relatives of subjects with schizophrenia. The present study aimed to examine clinical and neuropsychological characteristics in two different groups of first degree relatives of patients with schizophrenia - one of siblings (HRs), and one of offspring (HRo) - and compare them with healthy controls (HC).

METHODS

Participants were 30 HRo, 26 HRs and 33 HC, all aged between 7 and 16 years. Clinical and neuropsychological assessments were completed by all participants.

RESULTS

No significant differences were observed between HR groups in DSM-IV diagnoses. The most prevalent diagnosis in both HR samples was attention deficit/hyperactivity disorder (ADHD) followed by oppositional defiant disorder and generalized anxiety disorder. Both HR groups obtained worse scores than HC on prodromal symptoms, premorbid adjustment and behavioral problem scales. In cognitive areas, HRo performed worse than HC on most WISC-IV index scores, logical memory, visual memory and perceptual organization, whereas HRs only performed worse in WISC-IV indexes, logical memory and perceptual organization. Most of these differences remained stable after controlling for ADHD. The comparison between HRo and HRs showed significant differences in prodromal symptoms and working memory after controlling for ADHD.

CONCLUSION

Similar abnormalities in HRo and HRs were found in relation to clinical and neuropsychological variables. Subtle differences were found between HR groups with HRo showing difficulties in more clinical and neuropsychological areas than HRs and HC. This suggests that, the specific kind of family relationship should to be taken into account in future HR research.

Group and site differences on the California Verbal Learning Test in persons with schizophrenia and their first-degree relatives: findings from the Consortium on the Genetics of Schizophrenia (COGS)

Genetic studies of schizophrenia focus increasingly on putative endophenotypes because their genetic etiology may be simpler than clinical diagnosis. The Consortium on the Genetics of Schizophrenia (COGS), a multisite family study, aims to identify the genetic basis of several endophenotypes including verbal declarative memory (VDM), a neurocognitive function that shows robust impairment in schizophrenia. We present data on one type of measure of VDM, the California Verbal Learning Test, Second Edition (CVLT-II), in schizophrenia probands (n=305), their full biological siblings (n=449) and parents (n=232), and in community comparison subjects (CCS; n=509) across seven sites. Probands performed more poorly on each of five CVLT-II measures compared to related sibling and parent groups and CCS. Siblings and parents performed significantly worse than CCS on one measure (Discriminability), but with smaller effect sizes and less impairment than observed previously. The results raise questions about the homogeneity of VDM as an endophenotype, about methodological issues related to sampling, and about psychometric issues that impact the utility of the CVLT for detecting VDM deficits in nonpsychotic relatives of persons with schizophrenia.

Young offspring at genetic risk of adult psychoses: the form of the trajectory of IQ or memory may orient to the right dysfunction at the right time

Objective

Neurocognitive dysfunctions analogous to those of adult patients have been detected in children at risk of schizophrenia and bipolar disorder. This led to the following developmental question: Do IQ and memory impairments exhibit different developmental courses from childhood to young adulthood in terms of stability or fluctuations?

Methods

In a high risk sample, we used a step by step sampling approach to narrow-down the early disease mechanisms. Upstream, we started with a 20-year follow-up of 48 densely affected multigenerational kindreds, including 1500 clinically characterized adult members. We then identified 400 adult members affected by a DSM-IV schizophrenia or bipolar disorder. Downstream, we finally focused on 65 offspring (of an affected parent) aged 7 to 22, who were administered a neuropsychological battery. We then constructed cross-sectional trajectories that were compared to those of controls.

Results

The childhood IQ deficit displayed a stability until young adulthood. The delay in visual memory exhibited a non-linear two-stage trajectory: a lagging period during childhood followed by a recuperation period from adolescence until adulthood, as supported by a significant Group x Age Periods interaction. No data suggested deterioration between 7 and 22.

Conclusion

In these offspring at genetic risk, the developmental trajectory of global IQ impairment may not apply to specific domains of cognition such as episodic memory. Different cognitive dysfunctions would mark different developmental courses. The shape of the trajectories might itself have a meaning and provide empirical leads for targeting the right dysfunction at the right time in future prevention research.

Polymorphisms associated with normal memory variation also affect memory impairment in schizophrenia

Neurocognitive dysfunction is a core feature of schizophrenia with particularly prominent deficits in verbal episodic memory. The molecular basis of this memory impairment is poorly understood and its relatedness to normal variation in memory performance is unclear. In this study, we explore, in a sample of cognitively impaired schizophrenia patients, the role of polymorphisms in seven genes recently reported to modulate episodic memory in normal subjects. Three polymorphisms (GRIN2B rs220599, GRM3 rs2189814 and PRKCA rs8074995) were associated with episodic verbal memory in both control and patients with cognitive deficit, but not in cognitively spared patients or the pooled schizophrenia sample. GRM3 and PRKCA acted in opposite directions in patients compared to controls, possibly reflecting an abnormal brain milieu and/or adverse environmental effects in schizophrenia. The encoded proteins balance glutamate signalling vs. excitotoxicity in complex interactions involving the excitatory amino acid transporter 2 (EAAT2), implicated in the dysfunctional glutamatergic signalling in schizophrenia. Double carrier status of the GRM3 and PRKCA minor alleles was associated with lower memory test scores and with increased risk of schizophrenia. Single nucleotide polymorphism (SNP) rs8074995 lies within the PRKCA region spanned by a rare haplotype associated with schizophrenia in a recent UK study and provides further evidence of PRKCA contribution to memory impairment and susceptibility to schizophrenia. Our study supports the utility of parsing the broad phenotype of schizophrenia into component cognitive endophenotypes that reduce heterogeneity and enable the capture of potentially important genetic associations.

Declarative and nondeclarative memory in schizophrenia: What is impaired? What is spared?

The study's aim was to assess a broad range of declarative and nondeclarative memory functions in schizophrenia to identify areas of impairment versus relative preservation. Participants included 40 schizophrenia outpatients and 30 demographically comparable community residents. All participants were administered a battery assessing declarative memory (verbal learning, working memory, semantic memory, remote memory, verbal retention) and nondeclarative memory (procedural learning, priming). To control for order effects, the battery was divided into three parts of approximately equal length with order of administration counterbalanced across study participants. The results showed persons with schizophrenia to be significantly impaired relative to community residents in verbal learning, working memory, semantic memory, remote memory, and priming. In contrast, the two groups were comparable in verbal retention and procedural learning. In the schizophrenia group, priming ability best discriminated past year's vocational status. In sum, the findings indicate a specific pattern of impairment and preservation of memory functioning in schizophrenia. Skill (procedural) learning and retention of learned, declarative verbal information across a delay appear intact, while all other areas measured appear impaired.

Genetics and intermediate phenotypes of the schizophrenia--bipolar disorder boundary

Categorization of psychotic illnesses into schizophrenic and affective psychoses remains an ongoing controversy. Although Kraepelinian subtyping of psychosis was historically beneficial, modern genetic and neurophysiological studies do not support dichotomous conceptualization of psychosis. Evidence suggests that schizophrenia and bipolar disorder rather present a clinical continuum with partially overlapping symptom dimensions, neurophysiology, genetics and treatment responses. Recent large scale genetic studies have produced inconsistent findings and exposed an urgent need for re-thinking phenomenology-based approach in psychiatric research. Epidemiological, linkage and molecular genetic studies, as well as studies in intermediate phenotypes (neurocognitive, neurophysiological and anatomical imaging) in schizophrenia and bipolar disorders are reviewed in order to support a dimensional conceptualization of psychosis. Overlapping and unique genetic and intermediate phenotypic signatures of the two psychoses are comprehensively recapitulated. Alternative strategies which may be implicated into genetic research are discussed.

Premorbid cognitive deficits in young relatives of schizophrenia patients

Neurocognitive deficits in schizophrenia (SZ) are thought to be stable trait markers that predate the illness and manifest in relatives of patients. Adolescence is the age of maximum vulnerability to the onset of SZ and may be an opportune "window" to observe neurocognitive impairments close to but prior to the onset of psychosis. We reviewed the extant studies assessing neurocognitive deficits in young relatives at high risk (HR) for SZ and their relation to brain structural alterations. We also provide some additional data pertaining to the relation of these deficits to psychopathology and brain structural alterations from the Pittsburgh Risk Evaluation Program (PREP). Cognitive deficits are noted in the HR population, which are more severe in first-degree relatives compared to second-degree relatives and primarily involve psychomotor speed, memory, attention, reasoning, and social-cognition. Reduced general intelligence is also noted, although its relationship to these specific domains is underexplored. Premorbid cognitive deficits may be related to brain structural and functional abnormalities, underlining the neurobiological basis of this illness. Cognitive impairments might predict later emergence of psychopathology in at-risk subjects and may be targets of early remediation and preventive strategies. Although evidence for neurocognitive deficits in young relatives abounds, further studies on their structural underpinnings and on their candidate status as endophenotypes are needed.

Do people with schizophrenia have differential impairment in episodic memory and/or working memory relative to other cognitive abilities?

Efforts to identify differential or core cognitive deficits in schizophrenia have been made for several decades, with limited success. Part of the difficulty in establishing a cognitive profile in schizophrenia is the considerable inter-patient heterogeneity in the level of cognitive impairment. Thus, it may be useful to examine the presence of relative cognitive weaknesses on an intra-person level. In the present study we examined the rates of significant intra-person differences between crystallized verbal ability versus five other cognitive abilities among 127 persons with schizophrenia or schizoaffective disorder and 127 demographically matched normal comparison (NC) subjects. We found that the rates of significant discrepancies above the NC group base-rates was significantly greater in reference to those discrepancies involving visual memory relative to those associated with auditory memory, working memory, processing speed, and perceptual organization. The findings conflict with prior suggestions that working memory or auditory episodic memory are differential or core deficits in schizophrenia, and highlight the importance of considering visual memory in characterizing the cognitive effects of this condition.

Neurological disorders in schizophrenia

Schizophrenia (SZ) is a complex, heterogeneous, and disabling psychiatric disorder that impairs multiple aspects of human cognitive, perceptual, emotional, and behavioral functioning. SZ is relatively frequent (prevalence around 1%), with onset usually during adolescence or early adulthood, and has a deteriorating course. The rapidly growing area of neuroimaging research has has found clear evidence of many cortical and subcortical abnormalities in individuals with SZ. In this article the most recent findings from multiple studies on neurological disorders in SZ are reviewed, and the authors make a strong argument for a neurological basis of the schizophrenic process.

Of mice and men: bridging the translational disconnect in CNS drug discovery

The tremendous advances in transgene animal technology, especially in the area of Alzheimer's disease, have not resulted in a significantly better success rate for drugs entering clinical development. Despite substantial increases in research and development budgets, the number of approved drugs in general has not increased, leading to the so-called innovation gap. While animal models have been very useful in documenting the possible pathological mechanisms in many CNS diseases, they are not very predictive in the area of drug development. This paper reports on a number of under-appreciated fundamental differences between animal models and human patients in the context of drug discovery with special emphasis on Alzheimer's disease and schizophrenia, such as different affinities of the same drug for human versus rodent target subtypes and the absence of many functional genotypes in animal models. I also offer a number of possible solutions to bridge the translational disconnect and improve the predictability of preclinical models, such as more emphasis on good-quality translational studies, more pre-competitive information sharing and the embracing of multi-target pharmacology strategies. Re-engineering the process for drug discovery and development, in a similar way to other more successful industries, is another possible but disrupting solution to the growing innovation gap. This includes the development of hybrid computational models, based upon documented preclinical physiology and pharmacology, but populated and validated with clinical data from actual patients.

Dissociation of long-term verbal memory and fronto-executive impairment in first-episode psychosis

BACKGROUND

Verbal memory is frequently and severely affected in schizophrenia and has been implicated as a mediator of poor clinical outcome. Whereas encoding deficits are well demonstrated, it is unclear whether retention is impaired. This distinction is important because accelerated forgetting implies impaired consolidation attributable to medial temporal lobe (MTL) dysfunction whereas impaired encoding and retrieval implicates involvement of prefrontal cortex.

METHOD

We assessed a group of healthy volunteers (n=97) and pre-morbid IQ- and sex-matched first-episode psychosis patients (n=97), the majority of whom developed schizophrenia. We compared performance of verbal learning and recall with measures of visuospatial working memory, planning and attentional set-shifting, and also current IQ.

RESULTS

All measures of performance, including verbal memory retention, a memory savings score that accounted for learning impairments, were significantly impaired in the schizophrenia group. The difference between groups for delayed recall remained even after the influence of learning and recall was accounted for. Factor analyses showed that, in patients, all variables except verbal memory retention loaded on a single factor, whereas in controls verbal memory and fronto-executive measures were separable.

CONCLUSIONS

The results suggest that IQ, executive function and verbal learning deficits in schizophrenia may reflect a common abnormality of information processing in prefrontal cortex rather than specific impairments in different cognitive domains. Verbal memory retention impairments, however, may have a different aetiology.