Declarative memory and WCST-64 performance in subjects with schizophrenia and healthy controls

Correlation of Insulin-Like Growth Factor 1 With Cognitive Functions in Mild Traumatic Brain Injury Patients

Mild traumatic brain injury (mTBI) is a prevalent health concern with variable recovery trajectories, necessitating reliable prognostic markers. Insulin-like growth factor 1 (IGF-1) emerges as a potential candidate because of its role in cellular growth, repair, and neuroprotection. However, limited studies investigate IGF-1 as a prognostic marker in mTBI patients. This study aimed to explore the correlation of IGF-1 with cognitive functions assessed using the Wisconsin Card Sorting Test (WCST) in mTBI patients. We analyzed data from 295 mTBI and 200 healthy control participants, assessing demographic characteristics, injury causes, and IGF-1 levels. Cognitive functions were evaluated using the WCST. Correlation analyses and regression models were used to investigate the associations between IGF-1 levels, demographic factors, and WCST scores. Significant differences were observed between mTBI and control groups in the proportion of females and average education years. Falls and traffic accidents were identified as the primary causes of mTBI. The mTBI group demonstrated worse cognitive outcomes on the WCST, except for the "Learning to Learn" index. Correlation analyses revealed significant relationships between IGF-1 levels, demographic factors, and specific WCST scores. Regression models demonstrated that IGF-1, age, and education years significantly influenced various WCST scores, suggesting their roles as potential prognostic markers for cognitive outcomes in mTBI patients. We provide valuable insights into the potential correlation of IGF-1 with cognitive functions in mTBI patients, particularly in tasks requiring cognitive flexibility and problem solving.

Ketamine as a pharmacological tool for the preclinical study of memory deficit in schizophrenia

Schizophrenia is a serious neuropsychiatric disorder characterized by the presence of positive symptoms (hallucinations, delusions, and disorganization of thought and language), negative symptoms (abulia, alogia, and affective flattening), and cognitive impairment (attention deficit, impaired declarative memory, and deficits in social cognition). Dopaminergic hyperactivity seems to explain the positive symptoms, but it does not completely clarify the appearance of negative and cognitive clinical manifestations. Preclinical data have demonstrated that acute and subchronic treatment with NMDA receptor antagonists such as ketamine (KET) represents a useful model that resembles the schizophrenia symptomatology, including cognitive impairment. This latter has been explained as a hypofunction of NMDA receptors located on the GABA parvalbumin-positive interneurons (near to the cortical pyramidal cells), thus generating an imbalance between the inhibitory and excitatory activity in the corticomesolimbic circuits. The use of behavioral models to explore alterations in different domains of memory is vital to learn more about the neurobiological changes that underlie schizophrenia. Thus, to better understand the neurophysiological mechanisms involved in cognitive impairment related to schizophrenia, the purpose of this review is to analyze the most recent findings regarding the effect of KET administration on these processes.

Fluid Intelligence: Review of Foreign Studies

The present review focuses on modern research of fluid intelligence. The concept of fluid intelligence, the place of fluid intelligence in the structure of cognitive abilities, its relation to general intelligence is revealed. The current models of fluid intelligence are considered, including the current leading Cattell–Horn–Carroll model. The neurobiological processes underlying the flexibility of fluid reasoning processes in solving novel problems are discussed. In particular, studies are presented showing that fluid intelligence is mediated by subregions of the prefrontal cortex. Studies of the relationship between fluid intelligence and working memory, as well as studies of fluid intelligence in clinical groups such as children with ADHD and adults with schizophrenia are also discussed. Clinical evidence suggests that fluid intelligence may be key to understanding the structure of cognitive deficits in ADHD syndrome.

Clinical utility of the Multiple Errands Test in schizophrenia: A preliminary assessment

Schizophrenia (SZ) is a chronic, severe disease, which results in misperception of reality, major social withdrawal, and cognitive disturbances. One type of cognitive disturbance, known as executive dysfunction, is widely considered as a primary determinant of functional outcome. However, classic neuropsychological measures of executive functioning (EF) poorly represent patients' functional outcome, and thus seem inappropriate for evaluating the real-world functional impact of diseases such as SZ. We hypothesized that the Multiple Errands Test (MET), an ecological assessment of executive function would show greater ability to measure everyday adaptive functioning SZ, compared to conventional EF assessment methods. 100 clinically stable SZ patients were administered the MET, Wisconsin Card Sorting Test - 64 and a paper version of MET. Correlation analyses were performed between each EF measure and functional outcome, as measured by the Social Autonomy Scale (SAS). After adjusting for age, education, IQ and illness duration, SAS was significantly predicted by MET global score. No other EF measure correlated with SAS. Results from this study suggest that MET offers a valuable prediction of daily life functional outcome in this large sample of SZ patients. Therefore, it could be used as a complementary measure to improve the identification of executive dysfunctions prior to psychosocial interventions.

The relationship between executive functions and fluid intelligence in schizophrenia

An enduring question is unity vs. separability of executive deficits resulting from impaired frontal lobe function. In previous studies, we have asked how executive deficits link to a conventional measure of fluid intelligence, obtained either by standard tests of novel problem-solving, or by averaging performance in a battery of novel tasks. For some classical executive tasks, such as the Wisconsin Card Sorting Test (WCST), Verbal Fluency, and Trail Making Test B (TMTB), frontal deficits are entirely explained by fluid intelligence. However, on a second set of executive tasks, including tests of multitasking and decision making, deficits exceed those predicted by fluid intelligence loss. In this paper we discuss how these results shed light on the diverse clinical phenomenology observed in frontal dysfunction, and present new data on a group of 15 schizophrenic patients and 14 controls. Subjects were assessed with a range of executive tests and with a general cognitive battery used to derive a measure of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate. In line with our previous results, significant patient-control differences in classical executive tests were removed when fluid intelligence was introduced as a covariate. However, for tests of multitasking and decision making, deficits remained. We relate our findings to those of previous factor analytic studies describing a single principal component, which accounts for much of the variance of schizophrenic patients' cognitive performance. We propose that this general factor reflects low fluid intelligence capacity, which accounts for much but not all cognitive impairment in this patient group. Partialling out the general effects of fluid intelligence, we propose, may clarify the role of additional, more specific cognitive impairments in conditions such as schizophrenia.

The global cognitive impairment in schizophrenia: consistent over decades and around the world

OBJECTIVE

Schizophrenia results in cognitive impairments as well as positive, negative, and disorganized symptomatology. The present study examines the extent to which these cognitive deficits are generalized across domains, potential moderator variables, and whether the pattern of cognitive findings reported in schizophrenia has remained consistent over time and across cultural and geographic variation.

METHOD

Relevant publications from 2006 to 2011 were identified through keyword searches in PubMed and an examination of reference lists. Studies were included if they (1) compared the cognitive performance of adult schizophrenia patients and healthy controls, (2) based schizophrenia diagnoses on contemporary diagnostic criteria, (3) reported information sufficient to permit effect size calculation, (4) were reported in English, and (5) reported data for neuropsychological tests falling into at least 3 distinct cognitive domains. A set of 100 non-overlapping studies was identified, and effect sizes (Hedge's g) were calculated for each cognitive variable.

RESULTS

Consistent with earlier analyses, patients with schizophrenia scored significantly lower than controls across all cognitive tests and domains (grand mean effect size, g=-1.03). Patients showed somewhat larger impairments in the domains of processing speed (g=-1.25) and episodic memory (g=-1.23). Our results also showed few inconsistencies when grouped by geographic region.

CONCLUSIONS

The present study extends findings from 1980 to 2006 of a substantial, generalized cognitive impairment in schizophrenia, demonstrating that this finding has remained robust over time despite changes in assessment instruments and alterations in diagnostic criteria, and that it manifests similarly in different regions of the world despite linguistic and cultural differences.

Neurodevelopment in schizophrenia: the role of the wnt pathways

OBJECTIVES

To review the role of Wnt pathways in the neurodevelopment of schizophrenia.

METHODS

SYSTEMATIC PUBMED SEARCH, USING AS KEYWORDS ALL THE TERMS RELATED TO THE WNT PATHWAYS AND CROSSING THEM WITH EACH OF THE FOLLOWING AREAS: normal neurodevelopment and physiology, neurodevelopmental theory of schizophrenia, schizophrenia, and antipsychotic drug action.

RESULTS

Neurodevelopmental, behavioural, genetic, and psychopharmacological data point to the possible involvement of Wnt systems, especially the canonical pathway, in the pathophysiology of schizophrenia and in the mechanism of antipsychotic drug action. The molecules most consistently found to be associated with abnormalities or in antipsychotic drug action are Akt1, glycogen synthase kinase3beta, and beta-catenin. However, the extent to which they contribute to the pathophysiology of schizophrenia or to antipsychotic action remains to be established.

CONCLUSIONS

The study of the involvement of Wnt pathway abnormalities in schizophrenia may help in understanding this multifaceted clinical entity; the development of Wnt-related pharmacological targets must await the collection of more data.

Prediction of patient contacts by cognition in schizophrenia

OBJECTIVE

To investigate the correlations between cognitive function and clinical outcome variables.

METHOD

Patients diagnosed for the first time with schizophrenia between January 2004 and June 2010 were cognitively tested in conjunction with diagnostic procedures. Cognitive test data were connected to Danish healthcare registers and patients were followed in the registers from their first contact with psychiatric in- and outpatient care until October 2011.

RESULTS

Patients had impaired attention, processing speed and executive function as measured by Trail Making Test part B; their executive functions, as measured by the Wisconsin Card Sorting Test (WCST), and working memory, as measured by Rigshospitalet's digit span test, were unaffected as compared to norms. The admission rate, from schizophrenia diagnosis to the end of the study, was predicted by Trail Making Test part A, Rey's Auditory Verbal Learning Test (RAVLT), RAVLT (total learning), RAVLT (memory), d2 Test of Attention (total) and d2 type 2 error (error of commission), independent of gender, age and schizophrenia subtype. The length of hospitalization after the schizophrenia diagnosis was mainly determined by the schizophrenia subtype (schizophrenia simplex: incidence rate ratio (IRR) 0.24; 95% confidence interval (CI) 0.15-0.40, p < 0.001). Diagnosis was secondarily determined by deficits in attention and executive function, Trail Making Test part B, d2 Test of Attention (total), d2 type 1 error (error of omission), d2 type 2 error, and also by age and substance use disorder. The outpatient contact rate from schizophrenia diagnosis to the end of the study was predicted by d2 Test of Attention, Trail Making Test part A, and d2 type 2 error. The annual rate of criminal conviction, institutionalization and social retirement pension was mainly predicted by substance misuse.

CONCLUSION

Cognitive function only predicted hospitalization and outpatient contacts to a minor degree in a cohort of newly diagnosed patients with schizophrenia.