Semantic Organization and Verbal Memory Efficiency in Patients With Schizophrenia

Sex differences in the association between serum BDNF and cognitive impairment in schizophrenia patients using various antipsychotics

BACKGROUND

Cognitive impairment is one of the core symptoms of schizophrenia patients. There are often various differences in the efficacy of different antipsychotics in the treatment of cognitive impairment by sex. The purpose of this study was to explore whether there are gender differences in the association between serum BDNF levels and cognitive performance in patients with schizophrenia taking different antipsychotics.

METHODS

We used Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognitive function of three groups of schizophrenia patients (420 on clozapine, 183 on risperidone, 215 on typical antipsychotic drugs) and 467 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess schizophrenia symptoms of patients. Enzyme-Linked ImmunoSorbent Assay was used to measure serum brain-derived neurotrophic factor (BDNF) levels.

RESULTS

Among the patients taking clozapine and typical antipsychotic drugs, the RBANS total score, immediate memory, attention, and delayed memory subscores in females were higher than those in males (all p < 0.05). The RBANS total score and the delayed memory subscores in female patients taking risperidone were higher than those in male patients (all p < 0.05). Significant correlation between BDNF and cognition only existed in male patients taking clozapine, male patients taking risperidone, and male and female patients taking typical antipsychotic drugs (all p < 0.05).

CONCLUSION

Regardless of antipsychotic effect, the cognitive function of female patients is better compared to that of male patients. For male patients, the association between BDNF and cognitive performance exists in each medication group. For female patients, this significant association was only shown in the typical antipsychotic group, but not in the clozapine and risperidone groups.

A Feasibility Study on the Use of the Method of Loci for Improving Episodic Memory Performance in Schizophrenia and Non-clinical Subjects

We investigated the feasibility of a short intervention using the Method of Loci (MoL), a well-known visuospatial mnemonic, to improve episodic memory recall performance in schizophrenia. The MoL training protocol comprised encoding and recall of two lists of items (words and images), a training session and practice with MoL. Then, participants had the opportunity to put into practice the newly learned MoL and were instructed to encode and recall two new lists of items using. This approach was first validated with healthy individuals (N = 71). Subsequently, five individuals with schizophrenia completed the protocol. Improvement in healthy individuals was observed for the word list (Wilcoxon effect size r = 0.15). No significant memory improvement was denoted in the schizophrenia group, possibly due to participants' difficulties using the method efficiently and due to fatigue. The MoL seems to require episodic memory, working memory monitoring and executive functions, making it suboptimal for a population with impairments in all those domains. Future research should examine the use of other strategies, better suited for individuals with cognitive impairments like those found in schizophrenia.

Metacognitive preserved generation strategy benefits for both younger and elderly participants with schizophrenia

Cognitive memory and introspection disturbances are considered core features of schizophrenia. Moreover, it remains unclear whether or not participants with schizophrenia are more cognitively impaired with ageing than healthy participants. The aims of this study were to use a metacognitive approach to determine whether elderly participants with schizophrenia are able to improve their memory performance using a specific generation strategy and to evaluate the memory benefits for them using this strategy. 20 younger and 20 older participants with schizophrenia and their comparison participants matched for age, gender and education learned paired associates words with either reading or generation, rated judgment of learning (JOL) and performed cued recall. Participants with schizophrenia recalled fewer words than healthy comparison participants, but they benefited more from generation, and this difference was stable with ageing. Their JOL magnitude was lower than that of healthy comparison participants, but JOL accuracy was not affected by either age or the pathology. In spite of their memory deficit, elderly and younger participants with schizophrenia benefited remarkably from the memory generation strategy. This result gives some cause for optimism as to the possibility for participants with schizophrenia to reduce memory impairment if learning conditions lead them to encode deeply.

Role for Positive Schizotypy and Hallucination Proneness in Semantic Processing

Semantic processing underpins the organization of verbal information for both storage and retrieval. Deficits in semantic processing are associated with both the risk for and symptoms presented in schizophrenia. However, studies are mixed and could reflect the confounding effects of medication and symptom heterogeneity. Therefore, we considered whether two risk phenotypes, positive schizotypy and hallucinatory predisposition, present in the general population were associated with differential responding profiles for a semantic processing task. One hundred and eighty-three participants completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, National Adult Reading Test, a handedness measure, and a computerized semantic relatedness judgment task. Pairs of words were related through their dominant or subordinate meanings, or unrelated. Participants were divided into four groups using a mean split on cognitive-perceptual (positive) schizotypy and hallucination proneness. Significant differences between groups were found for reaction time on the semantic relatedness task, with the high cognitive-perceptual schizotypy groups responding significantly slower to all word pairs compared to their low scoring counterparts. There was some evidence that high hallucination proneness was associated with significantly faster reaction times which may reflect disinhibitive processes, however additional support is required. The results suggest that these two components of psychosis risk are associated with different patterns of responding to semantic processing. More diffuse activation of semantic information appeared to be associated with positive schizotypy, while those predisposed to hallucinations appeared to respond quicker. These results have significant implications in the re-conceptualization of hallucination proneness as distinct from positive schizotypy. Additional research is required to investigate the association between psychotic-like experiences separate from personality variables such as positive schizotypy and semantic processing.

Sex difference in cognitive impairment in drug-free schizophrenia: Association with miR-195 levels

OBJECTIVE

There is evidence that microRNA-195 (miR-195) is associated with schizophrenia (SZ) and cognition, but the relationship between miR-195 and cognitive impairment in SZ is still unknown. Sex differences in both microRNA (miRNA) expression and cognition were found in SZ. We aim to investigate whether sex moderates the relationship between miR-195 levels and cognition in SZ.

METHODS

We recruited 121 drug-free SZ patients and 129 healthy controls. miR-195 expression levels in peripheral blood mononuclear cells (PBMCs) were measured using qRT-PCR. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was performed to assess cognitive function. MANCOVA, ANCOVA, correlation analysis and hierarchical linear regression analysis were used to test the effect of sex on the aforementioned variables.

RESULTS

All RBANS scores significantly decreased in patients compared to healthy controls (all p < 0.001); ANCOVA analysis demonstrated female SZ patients had lower delayed memory score (F = 15.36, p < 0.001) and total score (F = 5.26, p = 0.024) than male patients. There was no diagnosis, sex or sex by diagnosis interaction effect on miR-195 levels (all p > 0.05). Interestingly, correlation analysis showed significant negative association between miR-195 and attention score (r = -0.389, p = 0.019), delayed memory score (r= -0.351, p = 0.036), and total score (r = -0.386, p = 0.020) only in female patients. Hierarchical regression analysis showed sex by miR-195 interaction was a significant predictor of the RBANS total score (ΔR2 = 0.042, F(1, 67) = 4.71, p = 0.033).

CONCLUSION

Our data indicate that miR-195 is associated with cognitive impairment in female SZ patients, and it may be involved in the underlying mechanism of sex differences in cognitive impairment in SZ.

Retrieval practice improves memory in patients with schizophrenia: new perspectives for cognitive remediation

BACKGROUND

Schizophrenia is associated with severe cognitive deficits, particularly episodic memory deficits, that interfere with patients' socio-professional functioning. Retrieval practice (also known as testing effect) is a well-established episodic memory strategy that involves taking an initial memory test on a previously learned material. Testing later produces robust long-term memory improvements in comparison to the restudy of the same material both in healthy subjects and in some clinical populations with memory deficits. While retrieval practice might represent a relevant cognitive remediation strategy in patients with schizophrenia, studies using optimal procedures to explore the benefits of retrieval practice in this population are still lacking. Therefore, the purpose of our study was to investigate the benefits of retrieval practice in patients with schizophrenia.

METHODS

Nineteen stabilised outpatients with schizophrenia (DSM-5 criteria) and 20 healthy controls first studied a list of 60 word-pairs (30 pairs with weak semantic association and 30 non associated pairs). Half the pairs were studied again (restudy condition), while only the first word of the pair was presented and the subject had to recall the second word for the other half (retrieval practice condition). The final memory test consisted in a cued-recall which took place 2 days later. Statistical analyses were performed using Bayesian methods.

RESULTS

Cognitive performances were globally altered in patients. However, in both groups, memory performances for word-pairs were significantly better after retrieval practice than after restudy (56.1% vs 35.7%, respectively, Pr(RP > RS) > 0.999), and when a weak semantic association was present (64.7% vs 27.1%, respectively; Pr(weak > no) > 0.999). Moreover, the positive effect of RP was observed in all patients but one.

CONCLUSIONS

Our study is the first to demonstrate that retrieval practice efficiently improves episodic memory in comparison to restudy in patients with schizophrenia. This learning strategy should therefore be considered as a useful tool for cognitive remediation programs. In this perspective, future studies might explore retrieval practice using more ecological material.

Gender differences of neurocognitive functioning in patients with first-episode schizophrenia in China

AIMS

To investigate the gender differences in neurocognitive functioning in patients with first-episode schizophrenia (FES) in China.

METHODS

A total of 449 Chinese patients with FES (210 males, 239 females) were included in this study. Participants' psychopathology was assessed by the Positive and Negative Syndrome Scale (PANSS). Neurocognitive functioning was assessed by 10 neuropsychological tests from a battery. Neurocognitive test scores were converted to scale scores and t-scores using normative data from Chinese populations.

RESULTS

Males were younger and less likely to be married, had an earlier age of illness onset and a longer duration of untreated psychosis (DUP), and scored higher on the PANSS negative, general and total scales than females. After controlling for potential confounders, females performed better than males in the verbal learning and memory domain (p=0.016). While most neurocognitive domains were correlated with PANSS negative scores for male patients with FES, for female patients with FES, negative associations were found between scores on the PANSS general subscales and neurocognitive domains. We also performed a case-control comparison with a group of patients with clinically stable schizophrenia (CSS) (n=60) who were matched by age, sex and education years with patients with FES (n=58). After controlling for potential confounders, no significant differences were found between patients with FES and patients with CSS in all neurocognitive domains. Female patients still performed better in the verbal learning and memory domain (t=2.14, p=0.034). No interaction effects of gender and disease were found.

CONCLUSIONS

Gender was an independent influence factor for the verbal learning and memory domain. Both female patients with first-episode schizophrenia and female patients with clinically stable schizophrenia performed better than male patients.

Do shared semantic features facilitate Lexical-semantic processing in early course psychosis?

The lexical-semantic relatedness effect supposes different activation in the semantic memory of related versus unrelated word-pairs. Semantically related pairs are considered to result in a larger spread of activation as the activation of concept nodes is dependent on shared lexical-semantic features of concepts. The increased activation of concepts in the semantic memory in individuals with schizophrenia is found to be, faster spreading and lacking in inhibition in relation to healthy control subjects. The aim of this study was to examine whether the lexical-semantic relatedness effect influences processing in individuals with early course psychosis by utilizing an explicit semantic matching task with 0ms SOA (Stimulus Onset Asynchrony) to analyse the strategy-free automatic spreading activation process. Overall, the patient group had lower accuracy and longer reaction times compared with healthy subjects, as well as better accuracy for related word-pairs and longer reaction times are for unrelated word-pairs. In clinical practice, the determination of language classifiers for early course psychosis could potentially enable the creation of reliable diagnostic markers and instruments for identifying the population with an elevated risk ofdeveloping disorders within a spectrum of schizophrenia, and predicting the course of the disorder.

The neuropsychology of emerging psychosis and the role of working memory in episodic memory encoding

Background

Episodic memory encoding and working memory (WM) deficits are among the first cognitive signs and symptoms in the course of schizophrenia spectrum disorders. However, it is not clear whether the deficit pattern is generalized or specific in nature. We hypothesized that encoding deficits at an early stage of the disease might be due to the more fundamental WM deficits.

Methods

We examined episodic memory encoding and WM by administering the California Verbal Learning Test, a 2-back task, and the Wisconsin Card Sorting Test in 90 first-episode psychosis (FE) patients and 116 individuals with an at-risk mental state for psychosis (ARMS) compared to 57 healthy subjects.

Results

Learning progress, but not span of apprehension, was diminished to a similar extent in both the ARMS and the FE. We showed that this was due to WM impairment by applying a structural equation approach.

Conclusion

Thus, we conclude that verbal memory encoding deficits are secondary to primary WM impairment in emerging psychosis.

A 10-minute measure of global cognition: Validation of the Brief Cognitive Assessment Tool for Schizophrenia (B-CATS)

INTRODUCTION

Schizophrenia is marked by a global cognitive impairment that contributes significantly to chronic disability and unemployment. As new treatments are developed for cognition in schizophrenia, clinicians require easily administered instruments to assess cognition. We previously developed a very brief cognitive battery (Bell et al., 2005). The Brief Cognitive Assessment Tool for Schizophrenia (B-CATS) was developed specifically to provide clinicians with a way to assess cognition in their patients with schizophrenia. Here, we report the results of a validity study comparing B-CATS to a larger neurocognitive battery, the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) battery.

METHODS

Outpatients with schizophrenia (N=91) were administered the B-CATS and the non-overlapping tests of the MATRICS battery at two time points separated by 1month. They were also administered the UCSD Performance-based Skills Assessment-Brief (UPSA-B), a measure of functional capacity.

RESULT

The B-CATS has an administration time of approximately 10min. It demonstrates good test-retest reliability and internal consistency. It correlates 0.76 (p<0.01) with the MATRICS battery. The shorter B-CATS and the MATRICS battery correlate with the UPSA-B at 0.50 and 0.58 respectively.

CONCLUSION

A 10-minute version of the B-CATS correlates highly with the "gold standard" neurocognitive battery that has an administration time of over 60min. Both measures correlate moderately with a measure of functional capacity. This brief battery was designed to allow clinicians to monitor cognitive change and better inform treatment decisions.

Differential patterns of contextual organization of memory in first-episode psychosis

Contextual information is used to support and organize episodic memory. Prior research has reliably shown memory deficits in psychosis; however, little research has characterized how this population uses contextual information during memory recall. We employed an approach founded in a computational framework of free recall to quantify how individuals with first episode of psychosis (FEP, N = 97) and controls (CON, N = 55) use temporal and semantic context to organize memory recall. Free recall was characterized using the Hopkins Verbal Learning Test-Revised (HVLT-R). We compared FEP and CON on three measures of free recall: proportion recalled, temporal clustering, and semantic clustering. Measures of temporal/semantic clustering quantified how individuals use contextual information to organize memory recall. We also assessed to what extent these measures relate to antipsychotic use and differentiated between different types of psychosis. We also explored the relationship between these measures and intelligence. In comparison to CON, FEP had reduced recall and less temporal clustering during free recall (p < 0.05, Bonferroni-corrected), and showed a trend towards greater semantic clustering (p = 0.10, Bonferroni-corrected). Within FEP, antipsychotic use and diagnoses did not differentiate between free recall accuracy or contextual organization of memory. IQ was related to free recall accuracy, but not the use of contextual information during recall in either group (p < 0.05, Bonferroni-corrected). These results show that in addition to deficits in memory recall, FEP differed in how they organize memories compared to CON.

First-episode psychosis patients exhibit impaired memory recall and deviation in how context is used to support recall ability. A US team of researchers led by the University of Pittsburgh’s Vishnu Murty examined how FEP affects an individual’s ability to organize memory based on context, by noting how well patients could recall words from a spoken list. Alongside recollection accuracy, Murty’s team assesed participant ability to recall words said proximally in sequence, and the ability to recall words from the same category—measuring ‘temporal clustering’ and ‘semantic clustering.’ The researchers found that patients with FEP had reduced recall ability and less temporal clustering. Recall accuracy and IQ were also found to be related. This study increases knowledge of FEP-related cognitive changes and could help to target specific therapies.

Verbal working memory in schizophrenia: The role of syntax in facilitating serial recall

BACKGROUND

Deficits in verbal working memory (VWM) have consistently been observed in schizophrenia, ranging from impairments in capacity, encoding, to irregular semantic organisation. However, syntactic deficits are less well-characterised, despite its crucial role in language construction. This study examines the role of simple syntactic structure (basis of the "sentence superiority effect") in VWM of patients with psychotic disorders.

METHODS

Patients with schizophrenia-spectrum disorders (n=40) and healthy controls matched on age, sex and education (n=40) were administered an auditory serial recall task containing word lists with low semantic coherence and either syntactically familiar structure (noun-verb-noun sequence) or syntactically unfamiliar structure. Other neurocognitive measures, symptoms and social functioning of patients were also assessed.

RESULTS

A 4-way analysis of variance (group×version×list type×serial position) indicated that patients had significantly worse performance overall, suggesting a generalised verbal memory impairment. In addition, a significant interaction was found for list type and Group, demonstrating that healthy controls, but not patients, had superior performance in syntactically familiar word lists. A subgroup analysis of high-performing patients revealed that the interaction was not an artefact of poor verbal memory, but a selective deficit in syntactic facilitation.

CONCLUSIONS

Our findings may suggest segregated mechanisms for maintenance and computational aspects of VWM, and show that even simple syntactic structure facilitates recall of syntactically unfamiliar words lists. Additionally, schizophrenic patients show difficulty utilising syntactic information, which highlights the need to understand the neuropsychological basis of working memory and linguistic impairments in psychosis.

Strategy for Semantic Association Memory (SESAME) training: Effects on brain functioning in schizophrenia

Self-initiation of semantic encoding strategies is impoverished in schizophrenia and contributes to memory impairments. Recently, we observed that following a brief training, schizophrenia patients had the potential to increase the self-initiation of these strategies. In this study, we investigated the neural correlates underlying such memory improvements. Fifteen schizophrenia patients with deficits in self-initiation of semantic encoding strategies were enrolled in a Strategy for Semantic Association Memory (SESAME) training. Patients underwent a memory task in an fMRI scanner. Memory performance and brain activity during the task were measured pre- and post- training, and changes following training were assessed. We also investigated if structural preservation measured by the cortical thickness of the left dorsolateral prefrontal cortex (DLPFC) predicted memory improvement post-training. Memory training led to significant improvements in memory performance that were associated with increased activity in the left DLPFC, during a task in which patients needed to self-initiate semantic encoding strategies. Furthermore, patients with more cortical reserve in their left DLPFC showed greater memory improvement. Our findings provide evidence of neural malleability in the left DLPFC in schizophrenia using cognitive strategies training. Moreover, the brain-behavioural changes observed in schizophrenia provide hope that memory performance can be improved with a brief intervention.

An Event Related Potentials Study of Semantic Coherence Effect during Episodic Encoding in Schizophrenia Patients

The objective of this electrophysiological study was to investigate the processing of semantic coherence during encoding in relation to episodic memory processes promoted at test, in schizophrenia patients, by using the N400 paradigm. Eighteen schizophrenia patients and 15 healthy participants undertook a recognition memory task. The stimuli consisted of pairs of words either semantically related or unrelated to a given category name (context). During encoding, both groups exhibited an N400 external semantic coherence effect. Healthy controls also showed an N400 internal semantic coherence effect, but this effect was not present in patients. At test, related stimuli were accompanied by an FN400 old/new effect in both groups and by a parietal old/new effect in the control group alone. In the patient group, external semantic coherence effect was associated with FN400, while, in the control group, it was correlated to the parietal old/new effect. Our results indicate that schizophrenia patients can process the contextual information at encoding to enhance familiarity process for related stimuli at test. Therefore, cognitive rehabilitation therapies targeting the implementation of semantic encoding strategies can mobilize familiarity which in turn can overcome the recollection deficit, promoting successful episodic memory performance in schizophrenia patients.

Differing Time of Onset of Concurrent TMS-fMRI during Associative Memory Encoding: A Measure of Dynamic Connectivity

There has been a distinct shift in neuroimaging from localization of function into a more network based approach focused on connectivity. While fMRI has proven very fruitful for this, the hemodynamic signal is inherently slow which limits the temporal resolution of fMRI-only connectivity measures. The brain, however, works on a time scale of milliseconds. This study utilized concurrent transcranial magnetic stimulation (TMS)-fMRI in a novel way to obtain measures of dynamic connectivity by measuring changes in fMRI signal amplitude in regions distal to the site of stimulation following differing TMS onset times. Seventeen healthy subjects completed an associative memory encoding task known to involve the DLPFC, viewing pairs of objects which could be semantically related or unrelated. Three pulses of 10 Hz repetitive TMS were applied over the left DLPFC starting either at 200, 600, or 1000 ms after stimulus onset. Associations for related pairs were better remembered than unrelated pairs in a post-scan cued recall test. Differences in neural activity were assessed across different TMS onsets, separately for related and unrelated pairs. Time specific TMS effects were observed in several regions, including those associated with higher-level processing (lateral frontal, anterior cingulate), visual areas (occipital), and regions involved in semantic processing (e.g., left mid-temporal and medial frontal). Activity in the frontal cortex was decreased at 200 ms post-stimulus for unrelated pairs, and 1000 ms post-stimulus for related pairs. This suggests differences in the timing across conditions in which the DLFPC interacts with other PFC regions, consistent with the notion that the DLPFC is facilitating extended semantic processing for related items. This study demonstrates that time-varying TMS onset inside the MRI can be used to reliably measure fast dynamic connectivity with a temporal resolution in the hundreds of milliseconds.

Prefrontal activity and impaired memory encoding strategies in schizophrenia

Schizophrenia patients have significant memory difficulties that have far-reaching implications in their daily life. These impairments are partly attributed to an inability to self-initiate effective memory encoding strategies, but its core neurobiological correlates remain unknown. The current study addresses this critical gap in our knowledge of episodic memory impairments in schizophrenia. Schizophrenia patients (n = 35) and healthy controls (n = 23) underwent a Semantic Encoding Memory Task (SEMT) during an fMRI scan. Brain activity was examined for conditions where participants were a) prompted to use semantic encoding strategies, or b) not prompted but required to self-initiate such strategies. When prompted to use semantic encoding strategies, schizophrenia patients exhibited similar recognition performance and brain activity as healthy controls. However, when required to self-initiate these strategies, patients had significant reduced recognition performance and brain activity in the left dorsolateral prefrontal cortex, as well as in the left temporal gyrus, left superior parietal lobule, and cerebellum. When patients were divided based on performance on the SEMT, the subgroup with more severe deficits in self-initiation also showed greater reduction in left dorsolateral prefrontal activity. These results suggest that impaired self-initiation of elaborative encoding strategies is a driving feature of memory deficits in schizophrenia. We also identified the neural correlates of impaired self-initiation of semantic encoding strategies, in which a failure to activate the left dorsolateral prefrontal cortex plays a key role. These findings provide important new targets in the development of novel treatments aiming to improve memory and ultimately patients' outcome.

Gender differences in cognitive deficits in schizophrenia with and without diabetes

This study investigated gender differences in cognition in schizophrenia with and without diabetes. Cognition was assessed in 263 individuals with schizophrenia with age range (40-68): 67 males and 34 females with schizophrenia with diabetes; and 125 males and 37 females with schizophrenia without diabetes according to the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Fasting glucose, hemoglobin A1c (HbA1c) and lipid levels were measured. Results showed that male individuals performed worse on most cognitive tasks, especially attention, in schizophrenia with than without diabetes. This result was not observed in female individuals. Also, individuals of both genders showed higher fasting glucose and HbA1c in schizophrenia with than without diabetes. In schizophrenia with diabetes, males had significantly worse cognition than females in all cognitive domains. Higher HbA1c, lower high-density lipoprotein, and an earlier age of onset of schizophrenia were found in males compared with female individuals. HbA1c was negatively associated with attention and the RBANS total score for males but not for females. In schizophrenia without diabetes, males showed worse performance in immediate and delayed memory than females. This study support cognition was worse for males with schizophrenia irrespective of whether they have diabetes. However, diabetes exemplified the gender differences, especially in attention.

Application of the Audio Recorded Cognitive Screen and its relation to functioning in schizophrenia

OBJECTIVE

This study investigated the ability of the Audio Recorded Cognitive Screen (ARCS) to detect cognitive deficit in individuals with schizophrenia, relative to the Mini Mental State Examination (MMSE) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and explored the associations between the ARCS and functional outcomes. We hypothesised that the ARCS would be able to better discriminate between individuals with schizophrenia and healthy controls than the MMSE, and that ARCS performance would be correlated with measures of social and vocational functioning.

METHODS

The participants were 19 community-dwelling individuals with schizophrenia or schizoaffective disorder and 19 healthy controls recruited from the Australian Schizophrenia Research Bank (ASRB). Participants completed the ARCS, MMSE, and self-report measures of social and vocational functioning. Clinical and diagnostic data stored by the ASRB were also utilised.

RESULTS

The schizophrenia group performed worse than the control group on the ARCS, with memory, t(36)=2.49, p=0.02, 95% CI [-1.84, -18.79] and fluency, t(36)=2.40, p=0.02, 95% CI [-1.87, -22.24] domains being the main discriminating measures. The RBANS also discriminated between the two groups, and ARCS and RBANS total scores were moderately to strongly correlated. There was no difference between the two groups on the MMSE after controlling for demographic variables. ARCS performance was associated with employment status [χ2(1)=7.16, p=0.007].

CONCLUSION

The ARCS may be sensitive to the cognitive deficits in outpatients with schizophrenia and an indicator of functional outcomes in this population.

Gender difference in association of cognition with BDNF in chronic schizophrenia

While numerous studies have reported that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia, very few studies have explored its association with cognitive impairment or gender differences in schizophrenia which we explored. We compared gender differences in 248 chronic schizophrenic patients (male/female=185/63) to 188 healthy controls (male/female=98/90) on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and serum BDNF. Schizophrenic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Our results showed that schizophrenic patients performed worse than normals on most of the cognitive tasks, and male patients had significantly lower immediate memory and delayed memory scores than female patients. BDNF levels were significantly lower in patients than controls, and male patients had significantly lower BDNF levels than female patients. For the patients, BDNF was positively associated with immediate memory and the RBANS total score. Furthermore, these associations were only observed in female not male patients. Among healthy controls, no gender difference was observed in cognitive domains and BDNF levels, or in the association between BDNF and cognition. Our results suggest gender differences in cognitive impairments, BDNF levels and their association in chronic patients with schizophrenia. However, the findings should be regarded as preliminary due to the cross-sectional design and our chronic patients, which need replication in a first-episode and drug naïve patients using a longitudinal study.

Task demand influences relationships among sex, clustering strategy, and recall: 16-word versus 9-word list learning tests

OBJECTIVE

We compared the relationships among sex, clustering strategy, and recall across different task demands using the 16-word California Verbal Learning Test-Second Edition (CVLT-II) and the 9-word Philadelphia (repeatable) Verbal Learning Test (PrVLT).

BACKGROUND

Women generally score higher than men on verbal memory tasks, possibly because women tend to use semantic clustering. This sex difference has been established via word-list learning tests such as the CVLT-II.

METHODS

In a retrospective between-group study, we compared how 2 separate groups of cognitively healthy older adults performed on a longer and a shorter verbal learning test. The group completing the CVLT-II had 36 women and 26 men; the group completing the PrVLT had 27 women and 21 men.

RESULTS

Overall, multiple regression analyses revealed that semantic clustering was significantly associated with total recall on both tests' lists (P<0.001). Sex differences in recall and semantic clustering diminished with the shorter PrVLT word list.

CONCLUSIONS

Semantic clustering uniquely influenced recall on both the longer and shorter word lists. However, serial clustering and sex influenced recall depending on the length of the word list (ie, the task demand). These findings suggest a complex nonlinear relationship among verbal memory, clustering strategies, and task demand.

Semantic processes leading to true and false memory formation in schizophrenia

Encoding semantic relationships between items on word lists (semantic processing) enhances true memories, but also increases memory distortions. Episodic memory impairments in schizophrenia (SZ) are strongly driven by failures to process semantic relations, but the exact nature of these relational semantic processing deficits is not well understood. Here, we used a false memory paradigm to investigate the impact of implicit and explicit semantic processing manipulations on episodic memory in SZ. Thirty SZ and 30 demographically matched healthy controls (HC) studied Deese/Roediger-McDermott (DRM) lists of semantically associated words. Half of the lists had strong implicit semantic associations and the remainder had low strength associations. Similarly, half of the lists were presented under "standard" instructions and the other half under explicit "relational processing" instructions. After study, participants performed recall and old/new recognition tests composed of targets, critical lures, and unrelated lures. HC exhibited higher true memories and better discriminability between true and false memory compared to SZ. High, versus low, associative strength increased false memory rates in both groups. However, explicit "relational processing" instructions positively improved true memory rates only in HC. Finally, true and false memory rates were associated with severity of disorganized and negative symptoms in SZ. These results suggest that reduced processing of semantic relationships during encoding in SZ may stem from an inability to implement explicit relational processing strategies rather than a fundamental deficit in the implicit activation and retrieval of word meanings from patients' semantic lexicon.

Cognitive correlates of verbal memory and verbal fluency in schizophrenia, and differential effects of various clinical symptoms between male and female patients

BACKGROUND

Impairment of higher cognitive functions in patients with schizophrenia might stem from perturbation of more basic functions, such as processing speed. Various clinical symptoms might affect cognitive efficiency as well. Notably, previous research has revealed the role of affective symptoms on memory performance in this population, and suggested sex-specific effects.

METHOD

We conducted a post-hoc analysis of an extensive neuropsychological study of 88 patients with schizophrenia. Regression analyses were conducted on verbal memory and verbal fluency data to investigate the contribution of semantic organisation and processing speed to performance. The role of negative and affective symptoms and of attention disorders in verbal memory and verbal fluency was investigated separately in male and female patients.

RESULTS

Semantic clustering contributed to verbal recall, and a measure of reading speed contributed to verbal recall as well as to phonological and semantic fluency. Negative symptoms affected verbal recall and verbal fluency in the male patients, whereas attention disorders affected these abilities in the female patients. Furthermore, depression affected verbal recall in women, whereas anxiety affected it in men.

CONCLUSIONS

These results confirm the association of processing speed with cognitive efficiency in patients with schizophrenia. They also confirm the previously observed sex-specific associations of depression and anxiety with memory performance in these patients, and suggest that negative symptoms and attention disorders likewise are related to cognitive efficiency differently in men and women.

Distinct episodic verbal memory profiles in schizophrenia

According to some authors, episodic memory impairment may be a feature shared by all schizophrenic patients, whereas others argue in favor of the mnesic heterogeneity. Our aims were to determine whether patients can be grouped based on according to their mnesic performances. The California Verbal Learning Test (CVLT), an episodic verbal learning test, was compared in 61 schizophrenic patients and 61 matched healthy subjects. The 32 indices were calculated using CVLT Scoring Software. This process allowed us to describe patients' episodic processes in detail (encoding, storage, retrieval). We isolated one group with normative data, another showed impairment of both encoding and retrieval processes, and in the last one, only encoding process was impaired. As schizophrenia is heterogeneous with regard to episodic memory, impairments should not be considered as a common core to the various forms of the illness and it would be fruitful to systematically assess episodic processes in detail to take into account individual abilities and challenges.

The influence of semantic processing on odor identification ability in schizophrenia

Despite the well-documented observation of odor identification deficits in schizophrenia, less is known about where the disruption in the process of correctly identifying an odor occurs. This study aimed to determine the potential moderating effects of semantic processing on the observed olfactory dysfunction in schizophrenia. Schizophrenia patients and healthy comparison subjects completed two versions of the University of Pennsylvania Smell Identification Test (UPSIT): an uncued free-response version and the standard multiple-choice paradigm, as well as three semantic measures: The Boston Naming Test, Animal Naming, and Pyramids and Palm Tree Test. Schizophrenia patients yielded significantly lower scores than the comparison group on the standard UPSIT and on semantic measures. No relationship was observed between olfactory and semantic task performance in patients. These data suggest that odor identification deficits may not be primarily due to semantic processing deficits in schizophrenia.

Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia

Several authors have noted that there are no reported cases of people with schizophrenia who were born blind or who developed blindness shortly after birth, suggesting that congenital or early (C/E) blindness may serve as a protective factor against schizophrenia. By what mechanisms might this effect operate? Here, we hypothesize that C/E blindness offers protection by strengthening cognitive functions whose impairment characterizes schizophrenia, and by constraining cognitive processes that exhibit excessive flexibility in schizophrenia. After briefly summarizing evidence that schizophrenia is fundamentally a cognitive disorder, we review areas of perceptual and cognitive function that are both impaired in the illness and augmented in C/E blindness, as compared to healthy sighted individuals. We next discuss: (1) the role of neuroplasticity in driving these cognitive changes in C/E blindness; (2) evidence that C/E blindness does not confer protective effects against other mental disorders; and (3) evidence that other forms of C/E sensory loss (e.g., deafness) do not reduce the risk of schizophrenia. We conclude by discussing implications of these data for designing cognitive training interventions to reduce schizophrenia-related cognitive impairment, and perhaps to reduce the likelihood of the development of the disorder itself.

Verbal and Visual Memory Impairments in Bipolar I and II Disorder

OBJECTIVE

To compare verbal and visual memory performances between patients with bipolar I disorder (BD I) and patients with bipolar II disorder (BD II) and to determine whether memory deficits were mediated by impaired organizational strategies.

METHODS

Performances on the Korean-California Verbal Learning Test (K-CVLT) and the Rey-Osterrieth Complex Figure Test (ROCF) in 37 patients with BD I, 46 patients with BD II and 42 healthy subjects were compared. Mediating effects of impaired organization strategies on poor delayed recall was tested by comparing direct and mediated models using multiple regression analysis.

RESULTS

Both patients groups recalled fewer words and figure components and showed lower Semantic Clustering compared to controls. Verbal memory impairment was partly mediated by difficulties in Semantic Clustering in both subtypes, whereas the mediating effect of Organization deficit on the visual memory impairment was present only in BD I. In all mediated models, group differences in delayed recall remained significant.

CONCLUSION

Our findings suggest that memory impairment may be one of the fundamental cognitive deficits in bipolar disorders and that executive dysfunctions can exert an additional influence on memory impairments.

The relationship of verbal learning and verbal fluency with written story production: implications for social functioning in first episode psychosis

BACKGROUND

Impairments in speech, communication and Theory of Mind are common in schizophrenia, and compromise social functioning. Some of these impairments may already be present pre-morbidly. This study aimed to investigate verbal functions in relation to written story production and social functioning in people experiencing a first episode of psychosis (FEP).

METHOD

Two groups of participants: FEP (N=31) and healthy controls (HC, N=31), completed measures of clinical status, social functioning, a series of neuropsychological tests targeting verbal functioning, and the "Frog Where Are You?" story production task.

RESULTS

Story results showed reduced efficiency (words per minute) and self-monitoring (corrections per minute) for FEP compared with HC groups (p<0.01). The FEP group performed significantly poorer than the HC group on most indices of verbal learning and verbal fluency. Story production was positively associated with verbal learning and verbal fluency for the FEP group only (p<0.05). Premorbid function decline was associated with impaired verbal learning and memory for the FEP group.

CONCLUSION

Individuals with FEP show a childhood history of reduced social and academic performance that is associated with skills essential for daily social interactions, as evidenced by the findings for story production, verbal learning and verbal fluency.

Strategic manipulations for associative memory and the role of verbal processing abilities in schizophrenia

Individuals with schizophrenia demonstrate episodic memory (EM) deficits and abnormal EM-related brain activity. Experimental encoding manipulations significantly benefit memory performance in schizophrenia, suggesting that a strategic processing deficit may contribute to memory impairment. However, few studies have investigated the combined effects of encoding and retrieval strategies on EM in schizophrenia. The current study examined the impact of encoding and retrieval strategies on associative memory and brain activity in schizophrenia. We also assessed the role of verbal processing ability in response to strategic memory interventions in schizophrenia. Behavioral and functional neuroimaging data were collected from 23 participants with schizophrenia and 24 comparison subjects while performing associative memory encoding and recall tasks. Behaviorally, both schizophrenia participants and controls benefited from memory strategies and showed significant associations between verbal processing ability and recall. Additionally, among schizophrenia participants, encoding strategy use was associated with enhanced brain activity in multiple brain areas. Schizophrenia participants also demonstrated significant associations between verbal processing ability and encoding-related brain activity in prefrontal cortex. Findings suggest that memory performance and brain activity in schizophrenia can be enhanced via strategic manipulations, and individual differences in cognitive abilities in schizophrenia can affect behavioral and neurobiological responses to strategic memory interventions.

Effect of explicit instruction on Japanese Verbal Learning Test in schizophrenia patients

After random assignment of 20 schizophrenia patients to either an explicit or normal instruction group, the Japanese Verbal Learning Test was administered to them. Results reveal that explicit instruction group patients demonstrated more improved memory performance using semantic clustering, suggesting that explicit and direct teaching facilitates patients' learning of information.

The role of encoding strategies in the verbal memory performance in patients with schizophrenia

BACKGROUND. Verbal learning and memory is often compromised in patients with schizophrenia who prefer encoding words in order of their presentation (serial clustering) rather than using semantic categories (semantic clustering). METHOD. One hundred and four in-patients with schizophrenia were assessed twice with the California Verbal Learning Test. RESULTS. Patients showed significantly less semantic than serial clustering at both assessment times. Usage of encoding strategies were not stable over time. An increase in semantic clustering improved recall and recognition performance. CONCLUSIONS. Patients with schizophrenia should be taught to use the more effective encoding strategy of semantic clustering in order to improve their memory performance.

A brief cognitive assessment tool for schizophrenia: construction of a tool for clinicians

Cognitive impairment in schizophrenia is often severe, enduring, and contributes significantly to chronic disability. But clinicians have difficulty in assessing cognition due to a lack of brief instruments. We evaluated whether a brief battery of cognitive tests derived from larger batteries could generate a summary score representing global cognitive function. Using data from 3 previously published trials, we calculated the corrected item-total correlations (CITCs) or the correlation of each test with the battery total score. We computed the proportion of variance that each test shares with the global score excluding that test (R(t)(2)=CITC(2)) and the variance explained per minute of administration time for each test (R(t)(2)/min). The 3 tests with the highest R(t)(2)/min were selected for the brief battery. The composite score from the trail making test B, category fluency, and digit symbol correlated .86 with the global score of the larger battery in 2 of the studies and correlated between .73 and .82 with the total battery scores excluding these 3 tests. A Brief Cognitive Assessment Tool for Schizophrenia (B-CATS) using the above 3 tests can be administered in 10-11 min. The full batteries of the larger studies have administration times ranging from 90 to 210 min. Given prior research suggesting that a single factor of global cognition best explains the pattern of cognitive deficit in schizophrenia, an instrument like B-CATS can provide clinicians with meaningful data regarding their patients' cognitive function. It can also serve researchers who want an estimate of global cognitive function without requiring a full neuropsychological battery.

Serial and semantic encoding of lists of words in schizophrenia patients with visual hallucinations

Previous research has suggested that visual hallucinations in schizophrenia are associated with abnormal salience of visual mental images. Since visual imagery is used as a mnemonic strategy to learn lists of words, increased visual imagery might impede the other commonly used strategies of serial and semantic encoding. We had previously published data on the serial and semantic strategies implemented by patients when learning lists of concrete words with different levels of semantic organisation (Brébion et al., 2004). In this paper we present a re-analysis of these data, aiming at investigating the associations between learning strategies and visual hallucinations. Results show that the patients with visual hallucinations presented less serial clustering in the non-organisable list than the other patients. In the semantically organisable list with typical instances, they presented both less serial and less semantic clustering than the other patients. Thus, patients with visual hallucinations demonstrate reduced use of serial and semantic encoding in the lists made up of fairly familiar concrete words, which enable the formation of mental images. Although these results are preliminary, we propose that this different processing of the lists stems from the abnormal salience of the mental images such patients experience from the word stimuli.

Brief neuropsychological profiles in psychosis: a pilot study using the Audio Recorded Cognitive Screen (ARCS)

Loughland CM, Allen J, Gianacas L, Schofield PW, Lewin TJ, Hunter M, Carr VJ. Brief neuropsychological profiles in psychosis: a pilot study using the Audio Recorded Cognitive Screen (ARCS).

OBJECTIVE

This pilot study examines the utility of a novel, standardised brief neuropsychological assessment tool (the ARCS, Audio Recorded Cognitive Screen) in a different clinical setting to that in which it was initially developed. We hypothesised that the ARCS would be feasible to administer to individuals with a psychotic illness and that it would detect cognitive deficits similar to those identified by an established instrument (the RBANS, Repeatable Battery for the Assessment of Neuropsychological Status).

METHODS

Twenty-five people with psychosis (mean age = 43.72, SD = 9.78) and 25 age- and gender-matched controls were recruited from the Newcastle community (NSW, Australia). The ARCS and RBANS were completed about 1 week apart in a counterbalanced order.

RESULTS

The ARCS was well received, performed satisfactorily and both the ARCS and RBANS were sensitive to deficits typically associated with psychosis (e.g. memory and attention). After controlling for memory deficits, the largest disparity between the psychosis and control groups was on the ARCS fluency domain [p < 0.001, partial Eta-squared (η p 2) = 0.21].

CONCLUSION

The ARCS uses audio administration (approximately 34 min) to reduce clinician time (to 3-5 min for scoring) and appears to be a useful brief assessment tool for examining the cognitive deficits associated with psychosis. However, the potential clinical utility of the ARCS needs to be investigated further in larger samples drawn from a wider variety of specialist and non-specialist settings.

Is semantic memory impaired in schizophrenia? A systematic review and meta-analysis of 91 studies

INTRODUCTION

Semantic memory impairments in schizophrenia have been reported across a wide range of neuropsychological tests. Set against a backdrop of fairly widespread cognitive impairments, it is difficult to know whether there is a primary, or secondary, impairment of semantic memory in schizophrenia. Also, whether there is a profile of differential impairment across the range of neuropsychological tests.

METHODS

Employing a systematic search strategy, 91 papers were identified which have assessed participants with schizophrenia on a measure of semantic memory. A series of meta-analyses were then conducted which provided combined weighted means for performance on tasks of naming, word-picture matching, verbal fluency, priming, and categorisation.

RESULTS

An uneven profile of impairment is reported with large effect sizes for tests of naming and verbal fluency, medium effect sizes for word-picture matching and association and small effect sizes for categorisation and priming tests.

CONCLUSIONS

This uneven profile supports the claim that a degradation of semantic knowledge may not be adequate in explaining the semantic memory impairment in schizophrenia. This conclusion is supported by the data which report a relationship between an executive dysfunction and poor priming and fluency performance particularly. The data support a link between Formal Thought Disorder and semantic memory impairments on tests of naming and verbal fluency but on other tests evidence is equivocal.

Memory for everyday actions in schizophrenia

In healthy people, enacting actions by manipulating objects improves memory compared to verbal encoding of the description of the same actions. We used this paradigm to test memory for actions in 40 stable schizophrenia participants and 24 healthy volunteers. Three encoding conditions were used and consisted of action sentences that were: 1) self-performed by the participants, 2) performed by an experimenter (observed), or 3) encoded verbally. Memory for those actions was tested in two formats. First a cued-recall task with the object as a retrieval cue was administered. Secondly source recognition was examined by asking the participants to decide in which of the three conditions each action was encoded. On cued-recall, schizophrenia participants largely benefited from self-enacting actions, reaching performance levels comparable to that of the healthy volunteers. On the source recognition test however, they showed a substantial impairment. The present study thus indicates that people with schizophrenia can benefit from the enactment effect. However, the fact that their performance was reduced considerably during source recognition relative to healthy volunteers suggests that the beneficial effect provided by enactment was mostly implicit.

Working memory in schizophrenia: a meta-analysis

BACKGROUND

Memory impairment is being recognized increasingly as an important feature of the neuropsychology of schizophrenia. Dysfunction of working memory, a system for the short-term storage and manipulation of information, may relate to a number of core symptoms of schizophrenia. Many studies have examined working memory function in schizophrenia but a clear understanding of the nature and extent of any deficit has been elusive.

METHOD

A systematic review and meta-analysis of studies comparing working memory function in subjects with schizophrenia and healthy controls was performed. Following a comprehensive literature search, meta-analyses were conducted on 36 measures of phonological, visuospatial and central executive working memory functioning, encompassing 441 separate results from 187 different studies.

RESULTS

Statistically significant effect sizes were found for all working memory measures, indicating deficits in schizophrenia groups. Some of these were robust findings in the absence of evidence of significant heterogeneity or publication bias. Meta-regression analyses showed that the working memory deficit was not simply explained by discrepancies in current IQ between schizophrenia and control groups.

CONCLUSIONS

Large deficits in working memory were demonstrated in schizophrenia groups across all three working memory domains. There were, however, no clear differences across subdomains or between particular working memory tasks. There was substantial heterogeneity across results that could only be partly explained.

Hallucinations and two types of free-recall intrusion in schizophrenia

BACKGROUND

Previous research has demonstrated that various types of verbal source memory error are associated with positive symptoms in patients with schizophrenia. Notably, intrusions in free recall have been associated with hallucinations and delusions. We tested the hypothesis that extra-list intrusions, assumed to arise from poor monitoring of internally generated words, are associated with verbal hallucinations and that intra-list intrusions are associated with global hallucination scores.

METHOD

A sample of 41 patients with schizophrenia was administered four lists of words, followed by free recall. The number of correctly recalled words and the number of extra- and intra-list intrusions were tallied.

RESULTS

The verbal hallucination score was significantly correlated with the number of extra-list intrusions, whereas it was unrelated to the number of correctly recalled words. The number of intra-list intrusions was significantly correlated with the global, but not with the verbal, hallucination score in the subsample of hallucinating patients. It was marginally significantly correlated with the delusion score in delusional patients.

CONCLUSIONS

The data corroborate the view that verbal hallucinations are linked to defective monitoring of internal speech, and that errors in context processing are involved in hallucinations and delusions.

Individual Differences in Episodic Memory: The Role of Self-initiated Encoding Strategies

Individuals' abilities to form and retrieve episodic memories vary widely. Consistent with this, there are substantial individual differences in brain activity during encoding and retrieval that are associated with individual differences in memory performance. Growing evidence suggests that individual differences in self-initiated encoding strategy use play an important role in individual differences in episodic memory and brain activity during intentional encoding. This review examines the role of individual differences in self-initiated encoding strategy use in individual differences in episodic memory, and outlines the major findings of brain lesion and functional neuroimaging studies that characterize the neural correlates of individual differences in self-initiated encoding strategy use. The relevance of individual differences in self-initiated encoding strategy use to understanding episodic memory impairments and alterations in brain activity in clinical populations such as individuals with schizophrenia is also discussed.

The relationship between prefrontal brain volume and characteristics of memory strategy in schizophrenia spectrum disorders

The present study investigated the relationship between memory strategy use and prefrontal gray/white matter volumes of healthy control subjects, patients with schizophrenia or schizotypal disorder. Gray/white matter volumes were measured for the superior, middle, inferior, ventral medial and orbital prefrontal regions, using high-resolution magnetic resonance (MR) images that were acquired from 35 patients with schizophrenia, 25 patients with schizotypal disorder and 19 healthy subjects. Participants were also administered the Japanese Verbal Learning Test (JVLT). In control subjects, larger left inferior frontal and straight gyrus's gray matter volumes were associated with higher semantic clustering rates on the JVLT, and smaller left inferior frontal gray matter volumes were associated with higher serial clustering ratio. In schizophrenic patients, smaller left orbitofrontal gray matter volumes were associated with lower semantic clustering rates on the JVLT. In schizotypal patients, smaller left inferior frontal white matter volume was associated with smaller serial clustering rates and larger semantic clustering rate. These findings suggest that semantic organization in schizophrenic patients might depend on mobilization of a memory strategy that is mediated by orbitofrontal cortex functioning. Failure to use a semantic organization strategy might be related to reduced volume in the inferior frontal gyrus. The findings for schizotypal patients suggest a compensation mechanism to remember the words using a serial processing strategy is at work when the inferior frontal gyrus cannot mediate semantic processing.

Pattern of memory compromise in chronic geriatric schizophrenia, frontotemporal dementia and normal geriatric controls

OBJECTIVE

The purpose of this study was to explore whether memory deficits in schizophrenia are attributable to poor organisation/encoding during initial learning vs. memory decay.

METHODS

Subjects included geriatric schizophrenia/schizoaffective disorders [SSD; n = 37; age = 59.92 (55-74); education = 11.70 (7-18)]; frontotemporal dementia [FTD; n = 41; age = 76.59 (64-83); education = 14.61 (12-20)] and geriatric controls [n = 107; age = 70.97 (55-93); education = 13.76 (6-20)]. Subjects were administered the Wechsler Memory Scale, Third Edition and discrepancy scores between immediate and delayed subtests/indices were used to explore possible differences between groups in pattern of impairment.

RESULTS

Significant differences were found between groups on age/education and these variables were related to several outcome measures. Gender was not related to diagnostic group and there were no gender differences on study variables. There were differences between the SSD subjects on several variables, with the schizoaffective subjects performing worse despite equivalence on global cognitive function, living status and chronicity. Seven one-way between-subjects ANCOVAs compared groups on discrepancy scores. RESULTS failed to suggest differences between groups on immediate-delayed memory discrepancy scores (p > 0.05). Subsequent analyses revealed differences in percentage retention scores between SSD and FTD on the faces subtest (p = 0.040), with SSD retaining greater information over time.

CONCLUSION

RESULTS failed to show distinctions between groups on pattern of memory impairment when using discrepancy comparisons. However, an analysis examining percentage retention scores revealed better maintenance of non-contextual visual information over time in SSD. Findings may suggest deficits in immediate encoding rather than memory decay for some types of memory ability among geriatric SSD. Our failure to document group differences when using discrepancy comparisons may be attributable to relative similarity in pattern between groups or the limited sensitivity of this technique.

Cognitive substrates in semantic memory of formal thought disorder in schizophrenia

Formal thought disorder (FTD) has been associated with abnormalities in the semantic memory system. However, it is still unclear whether these abnormalities are related to the organization of the semantic system, or to the automatic spread of activation-inhibition in semantic networks. In this paper these alternative proposals are examined. Schizophrenic patients and healthy matched controls were given two semantic memory tasks. In the first task, participants were required to judge the similarity between pairs of natural concepts. These ratings are assumed to reflect the underlying knowledge organization. In the second task, participants were required to name pictures that were preceded by related or unrelated word primes. Interference is typically observed when pictures are preceded by semantically related primes, and it is explained as due to inhibitory processes from the word prime to the related picture target. The results showed that the semantic structures derived from the similarity ratings were similar for patients with and without FTD and for control participants. However, results from the picture-naming task indicated that both non-FTD and control participants showed the normal interference/inhibition effects from the related prime words, whereas the patients with FTD showed similar performance for pictures preceded by related words than for pictures preceded by unrelated words. These findings support the hypothesis that abnormalities in inhibitory processes in semantic memory underlie FTD.

Functional mechanisms of episodic memory impairment in schizophrenia

OBJECTIVE

To achieve a better understanding of the functional mechanisms underlying episodic memory dysfunction in schizophrenia, which is a prerequisite for unravelling schizophrenia's neural correlates in neuroimaging studies and, more generally, for developing an integrated approach to the pathophysiology of schizophrenia. It is also crucial for developing cognitive remediation.

METHOD

This paper reviews empirical evidence of episodic memory dysfunction in schizophrenia obtained with reference to various theoretical models of episodic memory.

RESULTS

All the studies converge to show a significant impairment of the critical feature of episodic memory: conscious recollection. Schizophrenia is also associated with a defect of autobiographical memory. The episodic memory dysfunction results from a predominant failure of strategic processing at encoding, although an impairment of strategic processing at retrieval cannot be ruled out. The possibility that it is not the execution of the encoding strategies that is defective but, rather, their self-initiation by the patients is plausible.

CONCLUSIONS

These findings may explain some behavioural abnormalities associated with schizophrenia, notably, inadequate functional outcomes in everyday life. They may also have implications for cognitive remediation and better social and work functioning of patients with schizophrenia.

Subjective organisation in the free recall learning of adults with Asperger's syndrome

Single trial methods reveal unimpaired free recall of unrelated words in Asperger's syndrome (AS). When repeated trials are used (free recall learning), typical individuals show improved recall over trials, subjective organisation of material (SO) and a correlation between free recall and SO. We tested oral (Experiment 1) and written (Experiment 2) free recall over 16 trials in adults with AS and typical individuals. Across both experiments AS participants showed marginally diminished recall. Poorer SO was seen in the Asperger group only in Experiment 2, but in both experiments, individual differences in SO in the Asperger group were less likely to converge over trials. This lack of convergence suggests that the AS group organise material in idiosyncratic ways.

RBANS neuropsychological profiles within schizophrenia samples recruited from non-clinical settings

BACKGROUND

This paper examines the potential impact of recruitment source differences in schizophrenia research by comparing the neuropsychological performance of volunteers from the NISAD Schizophrenia Research Register with recently published schizophrenia normative data for the Repeatable Battery for Neuropsychological Status (RBANS).

METHODS

The Register sample comprised 285 volunteers with schizophrenia or schizoaffective disorder. Their RBANS performance was compared with US data from 575 predominantly outpatient-recruited schizophrenia patients.

RESULTS

The Register sample displayed impairments in immediate and delayed memory, but near-normal language, attention and visuospatial-constructional performance (mean RBANS total score=88.72, SD=16.35). By contrast, health service-recruited schizophrenia patients displayed impairments on all RBANS scales (mean RBANS total score=70.54, SD=14.80). Within the Register sample, volunteers with low levels of current functioning had immediate and delayed memory performance comparable to the US schizophrenia sample. Gender and school completion status were also associated with different RBANS profiles.

CONCLUSIONS

These findings reinforce the notion that a severity/functioning gradient exists across schizophrenia recruitment sources, which has important implications for research design and generalizability. Memory impairments have emerged as a central feature of schizophrenia.

A neuropsychological study of patients with temporal lobe epilepsy and chronic interictal psychosis

PURPOSE

To characterize the pattern of cognitive deficits in patients with temporal lobe epilepsy (TLE) and interictal (schizophrenia-like) psychosis and to examine the relationship between neuropsychological deficits and Magnetization transfer imaging.

METHODS

Twenty patients with TLE and interictal psychosis were compared to 20 non-psychotic TLE patients. Patients were matched with respect to premorbid IQ, age and conventional MRI findings. A battery of neuropsychological tests was administered. The neuropsychological tests which showed significant group differences were used for correlational analysis with magnetization transfer ratio (MTR) which provides a quantitative measure of macromolecular structural integrity.

RESULTS

Patients with interictal psychosis were significantly more impaired on executive and semantic memory tasks than the non-psychotic TLE group. Vocabulary test scores correlated significantly with MTR reduction in the left fusiform gyrus in the psychotic but not the non-psychotic group.

DISCUSSION

In this study, patients with TLE and interictal psychosis were more cognitively impaired than non-psychotic TLE patients. Our findings suggest that the cognitive deterioration in these patients may occur as the illness progresses and the causes for this are probably multifactorial. Our study also provides further evidence that MTR may be useful in investigating structural correlates of cognitive impairment.