Comparison of attention and brain functional connectivity between patient groups with schizophrenia and attention deficit hyperactivity disorder

Schizophrenia and attention deficit hyperactivity disorder (ADHD) have many contradicting features, but both these disorders share inattention as a core symptom. This study explored how the characteristics of inattention differ between the two disorders. 20 patients with schizophrenia, 20 patients with adult ADHD and 20 healthy controls participated in this study. Comprehensive attention test, Korean Wechsler adult intelligence scale-IV and resting-state functional magnetic resonance imaging (fMRI) were collected, among other things. The schizophrenia and ADHD groups showed low and high levels of functional connectivity in the default mode network (DMN), respectively. Functional connectivity level within the DMN was also positively correlated with processing speed index in the schizophrenia group and positively correlated with the number of divided-attention commission errors in the ADHD group. These results show that schizophrenia and adult ADHD have similarities in the characteristics of attention deficit, in that both may arise from dysregulation within the DMN. However, the differences in the levels of functional connectivity in the DMN between these groups affect how inattention manifests in each group.

Crystallized and fluid cognitive abilities have different genetic associations with neuropsychiatric disorders

Cognitive function is associated with risk for multiple neuropsychiatric disorders. Previous research on the genetic relations between cognition and psychopathology has largely treated cognitive function as unitary, in part due to a lack of well-powered genome-wide association studies (GWAS) on specific domains, particularly crystallized knowledge (Gc). Important domains within the hierarchy of cognitive function, especially Gc, have been underexplored regarding their associations with psychiatric disorders. Here, we parse the genetics of cognitive test performance into components representing reaction time, fluid reasoning, and crystallized knowledge. This multivariate approach that allows us to report results from a GWAS meta-analysis of crystallized knowledge (N ~ 438,000). We then test how multiple neuropsychiatric disorders with established links to cognitive function (Schizophrenia, Bipolar Disorder, Autism Spectrum Disorder, Attention Deficit Hyperactivity Disorder, and Alzheimer's Disease) are genetically related to these three cognitive domains, and to a noncognitive factor associated with educational attainment (NonCog). We document specific and heterogenous patterns of genetic associations between each neuropsychiatric disorder and the different domains of cognitive function and the noncognitive factor. Previous reports of genetic sharing between neuropsychiatric disorders and GWAS of aggregate cognitive function or educational attainment have failed identify these substantial differences in which cognitive functions drive these relations for which disorders.

Comparison of social cognition and neurocognition in schizophrenia and autism spectrum disorder: A systematic review and meta-analysis

BACKGROUND

This report aimed to compare group differences in social and non-social cognition in autism spectrum disorders (ASD) and schizophrenia, and examine the influence of age and other factors on group differences.

METHODS

Literature searches were conducted in Pubmed and Web of Science from January 1980 to August 2022. Original research articles reporting objective measures of cognition were selected.

RESULTS

57 articles involving 1864 patients with schizophrenia and 1716 patients with ASD have been included. Schizophrenia was associated with more severe non-social-cognitive impairment, particularly in fluency (g=0.47;CI[0.17-0.76]) and processing speed domains (g=0.41;CI[0.20-0.62]). Poorer performance in social cognition (Z = 3.68,p = 0.0002) and non-social cognition (Z = 2.48,p = 0.01) in schizophrenia were significantly related to older age. ASD was associated with more severe social cognitive impairment when groups were matched for non-social-cognition (g=-0.18, p = 0.04) or reasoning/problem solving (g=-0,62; CI [-1,06-(-0.08)].

DISCUSSION

While both disorders present with social and non-social cognitive impairments, the pattern and developmental trajectories of these deficits are different. The limitations included heterogeneity of the cognitive measures, and the lack of sufficient information about antipsychotic use.

Cognitive Profile Discrepancies among Typical University Students and Those with Dyslexia and Mixed-Type Learning Disorder

BACKGROUND

Previous studies have identified areas of cognitive weakness in children diagnosed with Specific Learning Disorder (SLD), in the areas of working memory and processing speed in particular. In adulthood, this literature is still scant, and no studies have compared the cognitive profile of university students with dyslexia (DD) with that of students with Mixed-type SLD.

METHOD

Thus, in this study, the WAIS-IV was used to examine the cognitive functioning of three groups of university students: students with DD, with Mixed-type SLD, and typical students. Statistical analyses were performed to examine differences in WAIS-IV FSIQ, main, and additional indexes and subtests.

RESULTS

The results showed strengths in perceptual reasoning and good verbal comprehension abilities in both the DD and Mixed-type SLD group, with weaknesses in working memory and processing speed, leading to a pattern of a better General Ability Index (GAI) than Cognitive Proficiency Index (CPI) in both clinical groups. Thus, discrepancies between GAI and CPI, well documented in children with SLD, still manifest in adulthood in university students. Our findings also revealed worse cognitive performance in university students with mixed learning disorder relative to students with only a reading deficit.

CONCLUSIONS

The cognitive features and distinctive subtest profiles that emerged should guide the assessment and the definitions of intervention programs, special educational needs, and strategies of compensation.

Abnormalities in visual cognition and associated impaired interactions between visual and attentional networks in schizophrenia and brief psychotic disorder

The extent and nature of cognitive impairment in brief psychotic disorder remains unclear, being rarely studied unlike schizophrenia. The present study hence sought to directly compare the visual cognitive dysfunction and its associated brain networks in brief psychotic disorder and schizophrenia. Data from picture completion (a complex visual task) and whole-brain functional connectome from resting-state fMRI were acquired from a sample of clinically stable patients with an established psychotic disorder (twenty with brief psychotic disorder, twenty with schizophrenia) and twenty-nine healthy controls. Group differences and the inter-relationships in task performances and brain networks were tested. Picture completion task deficits were found in brief psychotic disorder compared with healthy controls, though the deficits were less than schizophrenia. Task performance also correlated with severity of psychotic symptoms in patients. The task performance was inversely correlated with the functional connectivity between peripheral visual and attentional networks (dorsal attention and salience ventral attention), with increased functional connectivity in brief psychotic disorder compared with healthy controls and in schizophrenia compared with brief psychotic disorder. Present findings showed pronounced visual cognitive impairments in brief psychotic disorder that were worse in schizophrenia, underpinned by abnormal interactions between higher-order attentional and lower-order visual processing networks.

Advanced glycation end products and cognitive impairment in schizophrenia

Advanced glycation end products play a key role in the pathophysiology of schizophrenia. Cognitive impairment is one of the central features of schizophrenia; however, the association between advanced glycation end products and cognitive impairment remains unknown. This study investigated whether advanced glycation end products affect the cognitive domain in patients with schizophrenia. A total of 58 patients with chronic schizophrenia were included in this cross-sectional study. Plasma advanced glycation end products were measured using high-performance liquid chromatography (HPLC). Neuropsychological and cognitive functions were assessed using the Wechsler Adult Intelligence Scale, Third Version, and the Wisconsin Card Sorting Test Keio-FS version. Multiple regression analysis adjusted for age, sex, body mass index, educational years, daily dose of antipsychotics, and psychotic symptoms revealed that processing speed was significantly associated with plasma pentosidine, a representative advanced glycation end product (standardized β = -0.425; p = 0.009). Processing speed is the cognitive domain affected by advanced glycation end products. Considering preceding evidence that impaired processing speed is related to poor functional outcome, interventions targeted at reducing advanced glycation end products may contribute to promoting recovery of patients with schizophrenia as well as cognitive function improvement.

The Relationship of Functional Status of Cortisol, Testosterone, and Parameters of Metabolic Syndrome in Male Schizophrenics

Background

The cross-sectional study is aimed at investigating the relationship between cortisol, testosterone, and metabolic characteristics among male schizophrenics.

Methods

174 patients were grouped based on their risk of metabolic syndrome (MetS) into the non-MetS, high-risk-MetS (HR-MetS), or MetS groups. Metabolic indices (body mass index (BMI), mean arterial pressure (MAP), cholesterol, triglyceride, and fasting blood glucose (FBG)) were associated with cortisol and testosterone levels using correlation analysis. Multiple linear regression analysis was used to associate the correlations between the WHO Quality of Life–BREF (WHOQOL–BREF) score and the five metabolic indices.

Results

The WHOQOL–BREF score for the non-MetS group significantly differed from the scores of the HR-MetS and MetS groups. The triglyceride level was positively correlated with the cortisol level, while all five metabolic indices were negatively correlated with testosterone level. Stepwise regression analysis produced a model predicting WHOQOL–BREF scores with four variables including MAP, intelligence quotient (IQ), FBG, and age. The correlation analysis then showed that there was a weak linear correlation between the testosterone level and all five metabolic indices.

Conclusions

Among the five metabolic indices, the risks of hypertension and hyperglycemia are correlated with the quality of life in male schizophrenics rather than those of obesity or hyperlipidemia.

Psychotically driven aggression is associated with greater mentalizing challenges in psychotic spectrum disorders

BACKGROUND

Some aggressive acts committed by individuals with psychotic spectrum disorders (PSD) are understandable in the context of interpersonal conflict or goal attainment, yet others are unpredictable, arising from delusions or hallucinations (psychotically driven aggressive acts, PDA). It is unknown if there are underlying differences in cognitive or perceptive social cognition in relation to aggression motivation in PSD.

METHOD

We compared differences in social cognition performance between 49 individuals with PSD who had committed PDA with those exhibiting other types of aggression (n = 31) (non-PDA) and to community controls (n = 81) on the Swedish version of Double Movie for the Assessment of Social Cognition - Multiple Choice (DMASC-MC). Participants with PSD had more than 3 months of clinical stability and substance use abstention and stable antipsychotic medication doses. General intellectual ability was assessed with the information and matrix reasoning subtests of the Wechsler Intelligence Scales.

RESULTS

The PSD group with a history of PDA exhibited lower total and perceptive social cognition scores on the DMASC-MC than the non-PDA group and controls. In addition, they also showed lower cognitive scores compared to typical controls. Lower total scores were associated with lower scores on Wechsler intelligence subtests information and matrix reasoning. Taking this into account, the PDA group still had lower social cognition scores. There were no associations of antipsychotic medication dosages, positive or negative symptoms with social cognition scores. Higher antipsychotic dosage at the time of DMASC-MC testing and social cognition scores predicted a past history of PDA.

CONCLUSIONS

We conclude that impaired social cognition, particularly perceptive social cognition, is associated with PDA in individuals with PSD.

Organization framework and preliminary findings from the Athens First-Episode Psychosis Research Study

AIMS

Athens First-Episode Psychosis (FEP) Research study, aims to explore the potential associations between multiple genetic, environmental and neurometabolic risk factors of psychotic disorders, through the clinical management of FEP patients with minimal exposure (<2 weeks) to antipsychotic treatment at entry. The goal of this paper is to introduce the background, rationale and design of the study and present its preliminary findings.

METHODS

We developed a longitudinal cohort study of FEP patients 16-45 years old, presenting at the emergency units of five psychiatric hospitals across Athens, Greece. Research timeline includes baseline, 1-month and 1-year follow-up. Clinical, genetic, environmental, cognitive and biochemical parameters are measured, using psychometric tools, clinical interviews and laboratory tests. A descriptive analysis of baseline and 1-month assessments was performed including demographic characteristics, family history, medication, clinical picture, traumatic experiences, drug use and cognitive functioning.

RESULTS

During the last 3 years, 130 subjects have been enrolled in the study. Data so far reveal that, despite the severity of baseline presentation, at 1-month the majority (57.4%) met the Andreasen symptom severity criteria for remission, without the time criterion and showed mild functional improvement. Several environmental adversities and poor cognitive performance were identified, which need to be further elaborated.

CONCLUSIONS

Athens FEP Research study is the first gene-environment interaction study in Greece. In this article we introduce the organization and methodological framework of the project, along with its basic initial findings. Future analysis will allow the validation of tractable predictors and risk factors implicated in the development and outcome of psychosis.

Unified and disease specific alterations to brain structure in patients across six categories of mental disorders who experience own-thought auditory verbal hallucinations: A pilot study

OBJECTIVE

To explore the unified and disease specific structural features of the brain in patients spanning six mental disorders who experience own-thought auditory verbal hallucinations (OTAVH).

METHODS

A pilot study was conducted on 25 patients with schizophrenia (FUSCH-OTAVH), 20 patients with major depression disorder (FUMDD-OTAVH), 28 patients with bipolar disorder (FUBD-OTAVH), 22 patients with posttraumatic stress disorder (FUPTSD-OTAVH), 21 patients with anxiety disorder (FUAD-OTAVH), and 27 patients with borderline personality disorder (FUBPD-OTAVH). Twenty-five healthy controls (HCs) were also recruited. Auditory Hallucinations Rating Scale (AHRS) multiple psychometric scales were adopted to assess the clinical features of voxel-based morphometry (VBM), tract-based spatial statistics (TBSS), and multiple regression in all patients. Common and specific brain features of OTAVH among these mental disorders were investigated.

RESULTS

Compared to HCs, GMV aberrant pattern across all the six categories patients with OTAVH decreased in the occipital cortex, left parietal lobe, prefrontal cortex (PFC), and insular cortex (IC). Aberrant patterns in white matter (WM) were detected in the corpus callosum and impairment of the fronto-occipital fasciculus. Structural differences in the brain were observed for each mental disorder versus HCs.

CONCLUSIONS

The unified brain aberrant features of OTAVH across six mental disorders were characterized by decreased GMV and WM impairments in some regions and the specific brain features of each disease were also characterized. In conclusion, this study provides evidence for the structural basis of OTAVH and potential avenues for investigating disease specific brain features of OTAVH.

Preliminary examination of the validity of the NIH toolbox cognition battery in treatment-resistant psychosis

Objective: Prior research has suggested that treatment-resistant psychosis (TRP) may be a categorically distinct subtype from treatment-responsive psychotic disorders. However, relatively few studies have investigated the cognitive profile of individuals with TRP. Moreover, no prior studies have investigated the effectiveness of using the NIH Toolbox Cognition Battery (NTCB) for assessing cognition among psychiatric inpatients despite its promising efficiency and practicality in such settings. The current study aimed to investigate the validity of the NTCB and the associated cognitive profile of inpatients with TRP.Methods: Participants (N = 38) were administered the NTCB and a neuropsychological test battery. The Positive and Negative Syndrome Scale and the Routine Assessment of Patient Progress measured psychosis symptomatology and daily functioning, respectively.Results: Results showed deficits relative to normative values in fluid cognitive abilities using the NTCB, as predicted. There was strong convergent validity and adequate divergent validity between the NTCB subtests and corresponding neuropsychological measures, though no NTCB subtest correlated with performance on the Wisconsin Card Sorting Task. NTCB performance correlated with positive and disorganized symptoms of psychosis as well as daily functioning.Conclusions: Taken together, the NTCB appears to be a relatively strong tool for cognitive screening among psychiatric inpatients and may be used to identify which patients might benefit from further neuropsychological evaluation.

Intellectual functioning in Silver-Russell syndrome: First study in adults

Silver-Russell syndrome (SRS) is a rare genetic disorder (estimated incidence 1/30,000 to 100,000 live births). So far, only a few studies have focused on the cognitive profile of individuals with SRS, and these were conducted some time ago, concentrated on pediatric cohorts, and included patients who had been diagnosed using a variety of clinical diagnostic systems. There has yet to be any research on the intellectual functioning of adults with SRS. This study sought to establish the intelligence, strengths and weaknesses within intellectual profile of adults with SRS, compared with normative data. Ten individuals with 11p15 epimutation aged 18-39 years completed the Wechsler Adult Intelligence Scale-Fourth Edition. Measures of interest included participants' intelligence (Full Scale Intelligence Quotient [FSIQ]) and four domains of cognitive functioning: verbal comprehension, perceptual reasoning, working memory and processing speed. Discrepancy scores were calculated, and descriptive statistical and linear correlations were used to investigate factors associated with IQ outcome. Clinical and medical information such as rehabilitation, and perceived difficulties in daily life were collected by interviews and questionnaires. Results showed that the mean FSIQ score was in the average range (M = 95.40, SD = 18.55) and they performed best on verbal comprehension. Frequent daily difficulties were reported by patients and/or their families: learning disabilities and low self-esteem were perceived by 60% of adults. Early intervention and multidisciplinary care from childhood to adulthood are important in SRS for care potential medical, cognitive and psychosocial problems. This is the first study to document the intellectual functioning of adults with SRS.

WAIS-IV Performance in Patients With Schizophrenia

Wechsler Adult Intelligence Scale (WAIS) is one of the most widely used instruments to measure cognitive functioning. The aims of this study were 1) to obtain the cognitive profile of Spanish patients with schizophrenia on the WAIS-IV; 2) to compare their profile to the profile of a healthy control group; and 3) to compare the cognitive profile of patients with schizophrenia to the performance observed in two separate previous studies in Canada and China. A sample of 99 outpatients and 99 healthy control participants, matched on age, sex, and educational level, were measured using the WAIS-IV, including 10 core subtests, 4 indices, and 2 general intelligence scores, to obtain their cognitive profile. Results showed that only the performance on the Verbal Comprehension Index and its subtests was similar in the patient and control groups. This pattern of cognitive impairment was similar to the pattern reported in the Canadian and Chinese studies.

Feasibility of a web-based neurocognitive battery for assessing cognitive function in critical illness survivors

PURPOSE

To assess the feasibility of using a widely validated, web-based neurocognitive test battery (Cambridge Brain Sciences, CBS) in a cohort of critical illness survivors.

METHODS

We conducted a prospective observational study in two intensive care units (ICUs) at two tertiary care hospitals. Twenty non-delirious ICU patients who were mechanically ventilated for a minimum of 24 hours underwent cognitive testing using the CBS battery. The CBS consists of 12 cognitive tests that assess a broad range of cognitive abilities that can be categorized into three cognitive domains: reasoning skills, short-term memory, and verbal processing. Patients underwent cognitive assessment while still in the ICU (n = 13) or shortly after discharge to ward (n = 7). Cognitive impairment on each test was defined as a raw score that was 1.5 or more standard deviations below age- and sex-matched norms from healthy controls.

RESULTS

We found that all patients were impaired on at least two tests and 18 patients were impaired on at least three tests. ICU patients had poorer performance on all three cognitive domains relative to healthy controls. We identified testing related fatigue due to battery length as a feasibility issue of the CBS test battery.

CONCLUSIONS

Use of a web-based patient-administered cognitive test battery is feasible and can be used in large-scale studies to identify domain-specific cognitive impairment in critical illness survivors and the temporal course of recovery over time.

Intra-individual variability in neurocognitive function in schizophrenia: relationships with the corpus callosum

Patients with schizophrenia not only have impairments in neurological function, but also have instability and variability in neurocognitive function. However, previous researchers have not fully studied the relationships between dispersion across multiple neurocognitive domains and white matter (WM) structures of the brain. This study focuses on intra-individual variability (IIV) in patients with schizophrenia and its relationship with WM integrity of the corpus callosum (CC). Thirty-eight patients with schizophrenia were enrolled in the study. All subjects underwent assessments of neurocognitive function using the Korean-Wechsler Adult Intelligence Scale-Revised (K-WAIS-R) and the severity of clinical symptoms using the Positive and Negative Syndrome Scale (PANSS). IIV across subtests of the K-WAIS-R was calculated using the Holtzer's equation. Tract-based spatial statistics were used to analyze diffusion tensor images. In subjects with schizophrenia, a negative correlation was found between IIV in performance intelligence quotient (PIQ) and fractional anisotropy (FA) values in the genu of the CC. In addition, FA values of the same region were negatively correlated with the total and subscale scores of positive symptoms and general psychopathology from the PANSS. Our findings suggest that the genu of the CC may play an important role in IIV in PIQ and symptomatology in patients with schizophrenia.

The Screen for Cognitive Impairment in Psychiatry: Proposal for a polytomous scoring system

The Screen for Cognitive Impairment in Psychiatry is a simple, fast, and easy to administer scale that has been validated in clinical and community samples. The aim of this study was to propose a polytomous scoring system for the Screen for Cognitive Impairment in Psychiatry and to demonstrate its functioning, thus providing new and complementary information regarding the utility and precision of this screening tool. Three hundred seventy-six Spanish patients diagnosed with schizophrenia spectrum disorder were evaluated. A polytomous scoring system was generated and analyzed by means of the partial credit model. Category assessment revealed optimal functioning after collapsing the 7-category system to 1 with either 5 or 4 categories, depending on the item. The proposed polytomous scoring system shows good psychometric properties and an adequate fit to the partial credit model. These results provide further confirmation of the test's utility in clinical settings and of its suitability for detecting cognitive impairment.

Usefulness of the Wechsler Intelligence Scale short form for assessing functional outcomes in patients with schizophrenia

The Wechsler Adult Intelligence Scale (WAIS) has been widely used to assess intellectual functioning not only in healthy adults but also people with psychiatric disorders. The purpose of the study was to develop an optimal WAIS-3 short form (SF) to evaluate intellectual status in patients with schizophrenia. One hundred and fifty patients with schizophrenia and 221 healthy controls entered the study. To select subtests for SFs, following criteria were considered: 1) predictability for the full IQ (FIQ), 2) representativeness for the IQ structure, 3) consistency of subtests across versions, 4) sensitivity to functional outcome measures, 5) conciseness in administration time. First, exploratory factor analysis (EFA) and multiple regression analysis were conducted to select subtests satisfying the first and the second criteria. Then, candidate SFs were nominated based on the third criterion and the coverage of verbal IQ and performance IQ. Finally, the optimality of candidate SFs was evaluated in terms of the fourth and fifth criteria. The results suggest that the dyad of Similarities and Symbol Search was the most optimal satisfying the above criteria.

Anticholinergic burden in schizophrenia and ability to benefit from psychosocial treatment programmes: a 3-year prospective cohort study

BACKGROUND

Many medications administered to patients with schizophrenia possess anticholinergic properties. When aggregated, pharmacological treatments may result in a considerable anticholinergic burden. The extent to which anticholinergic burden has a deleterious effect on cognition and impairs ability to participate in and benefit from psychosocial treatments is unknown.

METHOD

Seventy patients were followed for approximately 3 years. The MATRICS consensus cognitive battery (MCCB) was administered at baseline. Anticholinergic burden was measured with the Anticholinergic Cognitive Burden (ACB) scale. Ability to benefit from psychosocial programmes was measured using the DUNDRUM-3 Programme Completion Scale (D-3) at baseline and follow-up. Psychiatric symptoms were measured using the PANSS. Total antipsychotic dose was measured using chlorpromazine equivalents. Functioning was measured using the Social and Occupational Functioning Assessment Scale (SOFAS).

RESULTS

Mediation analysis found that the influence of anticholinergic burden on ability to participate and benefit from psychosocial programmes was completely mediated by the MCCB. For every 1-unit increase on the ACB scale, change scores for DUNDRUM-3 decreased by -0.27 points. This relationship appears specific to anticholinergic burden and not total antipsychotic dose. Moreover, mediation appears to be specific to cognition and not psychopathology. Baseline functioning also acted as mediator but only when MCCB was not controlled for.

CONCLUSIONS

Anticholinergic burden has a significant impact on patients' ability to participate in and benefit from psychosocial treatment programmes. Physicians need to be mindful of the cumulative effect that medications can have on patient cognition, functional capacity and ability to benefit from psychosocial treatments.

WAIS-IV Seven-Subtest Short Form: Validity and Clinical Use in Schizophrenia

OBJECTIVE

This study assesses the psychometric properties of Ward's seven-subtest short form (SF) for WAIS-IV in a sample of adults with schizophrenia (SZ) and schizoaffective disorder.

METHOD

Seventy patients diagnosed with schizophrenia or schizoaffective disorder were administered the full version of the WAIS-IV. Four different versions of the Ward's SF were then calculated. The subtests used were: Similarities, Digit Span, Arithmetic, Information, Coding, Picture Completion, and Block Design (BD version) or Matrix Reasoning (MR version). Prorated and regression-based formulae were assessed for each version.

RESULTS

The actual and estimated factorial indexes reflected the typical pattern observed in schizophrenia. The four SFs correlated significantly with their full-version counterparts, but the Perceptual Reasoning Index (PRI) correlated below the acceptance threshold for all four versions. The regression-derived estimates showed larger differences compared to the full form. The four forms revealed comparable but generally low clinical category agreement rates for factor indexes. All SFs showed an acceptable reliability, but they were not correlated with clinical outcomes.

CONCLUSIONS

The WAIS-IV SF offers a good estimate of WAIS-IV intelligence quotient, which is consistent with previous results. Although the overall scores are comparable between the four versions, the prorated forms provided a better estimation of almost all indexes. MR can be used as an alternative for BD without substantially changing the psychometric properties of the SF. However, we recommend a cautious use of these abbreviated forms when it is necessary to estimate the factor index scores, especially PRI, and Processing Speed Index.

MRI correlates of general intelligence in neurotypical adults

There is growing interest in the neurobiological substrate of general intelligence. Psychometric estimates of general intelligence are reduced in a range of neurological disorders, leading to practical application as sensitive, but non-specific, markers of cerebral disorder. This study examined estimates of general intelligence in neurotypical adults using diffusion tensor imaging and resting-state functional connectivity analysis. General intelligence was related to white matter organisation across multiple brain regions, confirming previous work in older healthy adults. We also found that variation in general intelligence was related to a large functional sub-network involving all cortical lobes of the brain. These findings confirm that individual variance in general intelligence is related to diffusely represented brain networks.

An examination of the Wechsler Adult Intelligence Scales, Fourth Edition (WAIS-IV) in individuals with complicated mild, moderate and Severe traumatic brain injury (TBI)

This study examined the clinical utility of the Wechsler Adult Intelligence Scales-Fourth Edition (WAIS-IV) in individuals with complicated mild, moderate or severe TBI. One hundred individuals with TBI (n = 35 complicated mild or moderate TBI; n = 65 severe TBI) and 100 control participants matched on key demographic variables from the WAIS-IV normative dataset completed the WAIS-IV. Univariate analyses indicated that participants with severe TBI had poorer performance than matched controls on all index scores and subtests (except Matrix Reasoning). Individuals with complicated mild/moderate TBI performed more poorly than controls on the Working Memory Index (WMI), Processing Speed Index (PSI), and Full Scale IQ (FSIQ), and on four subtests: the two processing speed subtests (SS, CD), two working memory subtests (AR, LN), and a perceptual reasoning subtest (BD). Participants with severe TBI had significantly lower scores than the complicated mild/moderate TBI on PSI, and on three subtests: the two processing speed subtests (SS and CD), and the new visual puzzles test. Effect sizes for index and subtest scores were generally small-to-moderate for the group with complicated mild/moderate and moderate-to-large for the group with severe TBI. PSI also showed good sensitivity and specificity for classifying individuals with severe TBI versus controls. Findings provide support for the clinical utility of the WAIS-IV in individuals with complicated mild, moderate, and severe TBI.

Comparing Canadian and American normative scores on the Wechsler Adult Intelligence Scale-Fourth Edition

Psychologists practicing in Canada must decide which set of normative data to use for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). The purpose of this study was to compare the interpretive effects of applying American versus Canadian normative systems in a sample of 432 Canadian postsecondary-level students who were administered the WAIS-IV as part of an evaluation for a learning disability, attention-deficit hyperactivity disorder, or other mental health problems. Employing the Canadian normative system yielded IQ, Index, and subtest scores that were systematically lower than those obtained using the American norms. Furthermore, the percentage agreement in normative classifications, defined as American and Canadian index scores within five points or within the same classification range, was between 49% and 76%. Substantial differences are present between the American and Canadian WAIS-IV norms. Clinicians should consider carefully the implications regarding which normative system is most appropriate for specific types of evaluations.

Clinical utility of the Wechsler Adult Intelligence Scale-Fourth Edition after traumatic brain injury

The performance of 100 patients with traumatic brain injury (TBI) on the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) was compared with that of 100 demographically matched neurologically healthy controls. Processing Speed was the only WAIS-IV factor index that was able to discriminate between persons with moderate-severe TBI on the one hand and persons with either less severe TBI or neurologically healthy controls on the other hand. The Processing Speed index also had acceptable sensitivity and specificity when differentiating between patients with TBI who either did or did not have scores in the clinically significant range on the Trail Making Test. It is concluded that WAIS-IV Processing Speed has acceptable clinical utility in the evaluation of patients with moderate-severe TBI but that it should be supplemented with other measures to assure sufficient accuracy in the diagnostic process.

Comparison of intellectually disabled offenders with a combined history of sexual offenses and other offenses versus intellectually disabled offenders without a history of sexual offenses on dynamic client and environmental factors

Sexually offensive behavior is prevalent among individuals with intellectual disabilities (ID) and many sex offenders also commit other offenses such as vandalism or assault. We examined the differences between sex offenders with ID and a history of combined sex and other types of offenses (mixed sex offenders) versus offenders with no history of sexual offenses (non-sex offenders). Dynamic client and environmental factors were measured using the Adult Behaviour Checklist (ABCL) and the Risk Inventarization Scale on Sexually Offensive Behavior of Clients with intellectual disabilities (RISC-V). Item, subscale, and total scores were then compared for the two groups. Most of the comparisons did not reveal significant differences between the two groups. The findings call for a general theory of offending behavior to explain the absence of differences between the mixed sex offenders and non-sex offenders with ID.