Impaired working speed and executive functions as frontal lobe dysfunctions in young first-degree relatives of schizophrenic patients

d2-R test for Japanese adolescents: Concurrent validity with the attention deficit-hyperactivity disorder rating scale

BACKGROUND

The d2-R test is a cancellation test developed in Germany to measure concentration and attention. This study examined the validity of the d2-R test for Japanese adolescents in comparison with German standardized data.

METHODS

Japanese junior high school students (n = 121; 61 girls, 60 boys) participated in this study. The students' performance scores in the d2-R test were compared with their daily attentiveness and hyperactivity/impulsiveness assessments conducted by the teachers. The assessments were evaluated using the attention deficit-hyperactivity disorder rating scale, fourth edition (ADHD-RS)-IV. The comparison with German counterparts was also made.

RESULTS

Students who were rated as less attentive and more hyperactive/impulsive performed more slowly and committed more errors in the d2-R test. Although there were no sex differences in any of the d2-R parameters, male students were rated higher than female students in all of the ADHD-RS-IV scores. Japanese adolescents outscored German counterparts on speed, concentration, and carefulness.

CONCLUSION

The concurrent validity of the d2-R test is confirmed. It is an appropriate index to measure the sustained and focused attention of Japanese adolescents. The present research merits attention as the first investigation of the d2-R test conducted for Japanese adolescents.

Cognitive deficits in youth with familial and clinical high risk to psychosis: a systematic review and meta-analysis

OBJECTIVE

It is likely that cognitive deficits are vulnerability markers for developing schizophrenia, as these deficits are already well-established findings in first-episode psychosis. Studies at-risk adolescents and young adults are likely to provide information about cognitive deficits that predate the onset of the illness.

METHOD

We conducted meta-analyses of studies comparing familial-high risk (FHR) or ultra-high risk (UHR; n = 2113) and healthy controls (n = 1748) in youth studies in which the mean age was between 15 and 29.

RESULTS

Compared with controls, high risk subjects were impaired in each domain in both UHR (d = 0.34-0.71) and FHR (d = 0.24-0.81). Heterogeneity of effect sizes across studies was modest, increasing confidence to the findings of the current meta-analysis (I(2) = 0-0.18%). In both risk paradigms, co-occurrence of genetic risk with attenuated symptoms was associated with more severe cognitive dysfunction. In UHR, later transition to psychosis was associated with more severe cognitive deficits in all domains (d = 0.31-0.49) except sustained attention. However, cognitive impairment has a limited capacity to predict the outcome of high-risk patients.

CONCLUSION

Cognitive deficits are already evident in adolescents and young adults who have familial or clinical risk for psychosis. Longitudinal developmental studies are important to reveal timing and trajectory of emergence of such deficits.

Response initiation in young adults at risk for psychosis in the Northern Finland 1986 Birth Cohort

INTRODUCTION

This is one of the very few studies to investigate the specific executive function/processing speed component of response initiation in subjects at familial risk (FR) for psychosis, and the first such study in subjects at clinical risk (CR) for psychosis.

METHODS

Participants (N = 177) were members of the general population-based Northern Finland 1986 Birth Cohort in the following four groups: FR for psychosis (n = 62), CR for psychosis (n = 21), psychosis (n = 25) and control subjects (n = 69). The response initiation of these groups was compared in three different tests: Semantic fluency, Stockings of Cambridge and Spatial working memory.

RESULTS

The two risk groups did not differ significantly from control group, but differed from, and outperformed the psychosis group in semantic fluency response initiation.

CONCLUSIONS

Response initiation deficits were not evident in a non-help seeking psychosis high-risk sample.

A review of cognitive neuropsychiatry in the taxonomy of eating disorders: state, trait, or genetic?

A greater understanding of neuropsychological traits in eating disorders may help to construct a more biologically based taxonomy. The aim of this paper is to review the current evidence base of neuropsychological traits in people with eating disorders. Evidence of difficulties in set shifting, weak central coherence, emotional processing difficulties, and altered reward sensitivity is presented for people both in the acute and recovered phase of the illness. These traits are also seen in first degree relatives. At present there is limited research linking these neuropsychological traits with genetic and neuroanatomical measures. In addition to improving the taxonomy of eating disorders, neuropsychological traits may be of value in producing targeted treatments.

Neurocognition in youth and young adults under age 30 at familial risk for schizophrenia: a quantitative and qualitative review

INTRODUCTION

Neurocognitive dysfunction is a central feature of schizophrenia and is observed during all phases of the illness. Because schizophrenia is known to run in families, studying neurocognitive function in first-degree, nonpsychotic relatives has been a widely utilised strategy for almost 50 years for understanding presumed "genetic risk". Studying nonpsychotic relatives ("familial high-risk", or FHR) allows for identification of cognitive vulnerability markers independent of confounds associated with psychosis.

METHODS

Prior meta-analyses have elucidated the level and pattern of cognitive deficits in the premorbid, prodromal, and postonset periods of psychosis, and in relatives regardless of age. However, no prior quantitative analyses have specifically focused on studies of young first-degree relatives of individuals with schizophrenia who have not passed through the peak age illness risk (<age 30). The English language literature of neuropsychological studies of first-degree relatives for schizophrenia was identified up to 15 May 2011.

RESULTS

From 33 studies, 28 studies met our criteria for quantitative review, utilising >70 individual tests and 250 variables.

CONCLUSIONS

In general, young FHR individuals demonstrated deficits with a moderate level of severity compared with healthy controls. The largest average effect sizes (ESs), based on tests given in at least three independent studies, were on estimates of Full Scale IQ (d= -0.777), followed by Vocabulary (d= -0.749) and single word reading tests (d= -0.698) (often used as estimates of IQ). Measures of declarative memory, sustained attention, working memory and others had more modest ESs. Deficits were milder than in established schizophrenia, but often as severe as in clinical high-risk or putatively prodromal participants and in older relatives examined in prior meta-analyses. Additionally, while assessed from a more limited literature, youth at FHR for schizophrenia tended to show worse neurocognitive functioning than those at FHR for affective psychosis. This suggests that genetic risk for schizophrenia as reflected in a positive FHR carries an especially heavy impact on cognitive ability.

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Dimensions of executive functioning in schizophrenia and their relationship with processing speed

CONTEXT

The nature of executive dysfunction in schizophrenia is nebulous, due to inconsistencies in conceptualizing and operationalizing the construct, and the broader question of whether schizophrenia is best characterized in terms of specific vs generalized cognitive deficits. The current study aimed to determine whether executive functions represent unitary vs diverse constructs in schizophrenia.

METHODS

Participants included 145 community-dwelling individuals with schizophrenia. Executive functions were measured with the Delis-Kaplan Executive Functioning System (D-KEFS). We conducted an exploratory factor analysis (EFA) with principal axis factoring, as well as parallel analyses to examine the latent constructs underlying the D-KEFS tasks, a second EFA on weighted residuals of the D-KEFS tasks (after accounting for processing speed measured with the Digit Symbol task), and bivariate correlations to examine relationships between the D-KEFS components and relevant demographic and clinical variables, crystallized verbal knowledge, and functional capacity.

RESULTS

EFA of the D-KEFS tasks yielded 2 factors (cognitive flexibility/timed tests and abstraction). EFA of the processing speed-weighted D-KEFS residuals also yielded 2 factors (cognitive flexibility and abstraction). Cognitive flexibility was negatively correlated with psychopathology. Better abstraction was associated with higher education, shorter illness duration, and better functional capacity. Both factors were positively correlated with crystallized verbal knowledge.

CONCLUSIONS

Executive functions in schizophrenia could be parsed into 2 partially related but separable subconstructs. Future efforts to elucidate functional outcomes as well as neurobiological underpinnings of schizophrenia may be facilitated by attending to the distinction between cognitive flexibility and abstraction.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Sustained attention and working memory deficits follow a familial pattern in schizophrenia

Cognitive deficits are core features of schizophrenia and considered putative endophenotypes. This study assessed the familial pattern of deficits in sustained attention, working memory and executive function in remitted-schizophrenia patients and their unaffected siblings. Sixteen patients, 16 unaffected siblings, and 17 healthy control subjects underwent a battery of neuropsychological tasks that have so far yielded mixed findings in performance differences. Both groups had prolonged reaction times compared with controls in sustained attention tasks; the siblings made more false alarms in the working memory task, but only the patients' performance was poorer in the executive function tasks. These findings further support sustained attention and working memory deficits as potential endophenotypes of schizophrenia. Reaction time and false alarm rates are suggested as additional useful endophenotypic measures that could potentially account for differences in performance in tasks that are not purported to examine the specific measures per se.

Different vulnerability indicators for psychosis and their neuropsychological characteristics in the Northern Finland 1986 Birth Cohort

This study is one of very few that has investigated the neuropsychological functioning of both familial and clinical high risk subjects for psychosis. Participants (N = 164) were members of the Northern Finland 1986 Birth Cohort in the following four groups: familial risk for psychosis (n = 62), clinical risk for psychosis (n = 20), psychosis (n = 13), and control subjects (n = 69). The neurocognitive performance of these groups was compared across 19 cognitive variables. The two risk groups did not differ significantly from controls, but differed from the psychosis group in fine motor function. Neuropsychological impairments were not evident in a non-help-seeking high-risk sample.

Set shifting and working memory in adults with attention-deficit/hyperactivity disorder

Compared to the high number of studies that investigated executive functions (EF) in children with attention-deficit/hyperactivity disorder (ADHD), a little is known about the EF performance of adults with ADHD. This study compared 37 adults with ADHD (ADHD(total)) and 32 control participants who were equivalent in age, intelligence quotient (IQ), sex, and years of education, in two domains of EF--set shifting and working memory. Additionally, the ADHD(total) group was subdivided into two subgroups: ADHD patients without comorbidity (ADHD(-), n = 19) and patients with at least one comorbid disorder (ADHD(+), n = 18). Participants fulfilled two measures for set shifting (i.e., the trail making test, TMT and a computerized card sorting test, CKV) and one measure for working memory (i.e., digit span test, DS). Compared to the control group the ADHD(total) group displayed deficits in set shifting and working memory. The differences between the groups were of medium-to-large effect size (TMT: d = 0.48; DS: d = 0.51; CKV: d = 0.74). The subgroup comparison of the ADHD(+) group and the ADHD(-) group revealed a poorer performance in general information processing speed for the ADHD(+) group. With regard to set shifting and working memory, no significant differences could be found between the two subgroups. These results suggest that the deficits of the ADHD(total) group are attributable to ADHD rather than to comorbidity. An influence of comorbidity, however, could not be completely ruled out as there was a trend of a poorer performance in the ADHD(+) group on some of the outcome measures.

Stroop and emotional Stroop interference in unaffected relatives of patients with schizophrenic and bipolar disorders: distinct markers of vulnerability?

Reduced inhibition has been demonstrated in both schizophrenic and bipolar patients through the findings of increased interference on the Stroop Colour-Word Task (SCWT) and increased emotional interference on specific versions of the Emotional Stroop Task (EST). Despite previous findings of enhanced interference in unaffected relatives of schizophrenic and bipolar patients, it remains unclear whether interference might be a candidate endophenotype to both disorders. Moreover, data regarding emotional interference in unaffected relatives are critically lacking. In the present study, we aimed to compare unaffected relatives of patients with schizophrenia (SZ-rel, N = 30) and bipolar disorder (BD-rel, N= 30) with normal controls (N = 60) when performing the SCWT and an EST designed with neutral, depressive, paranoid and manic words. SZ-rel exhibited greater interference effect on both the SCWT and the EST as compared to either BD-rel or normal controls. BD-rel, and by contrast to SZ-rel and controls, showed increased emotional interference effect on the EST that was specifically associated to the disease-related words. The findings support the hypothesis of different markers of vulnerability to schizophrenic and bipolar disorders; impairment in cognitive inhibition could characterize high-risk individuals for schizophrenia whereas an emotional bias towards mood-related information could be a trait marker of bipolar disease.

Premorbid cognitive deficits in young relatives of schizophrenia patients

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

Inefficient neural activity in patients with schizophrenia and nonpsychotic relatives of schizophrenic patients: evidence from a working memory task

Studies of schizophrenia with functional MRI have shown hyper- and hypoactivations in various brain regions including the prefrontal cortex. Functional anomalies have also been reported in first-degree relatives of schizophrenic patients. The aim of this study was to examine working memory related brain functions in healthy subjects, schizophrenic patients and unaffected relatives and to determine the influence of psychopathology on these processes. A parametric n-back working memory task and functional MRI were used to examine 61 patients with schizophrenia, 11 nonpsychotic relatives of schizophrenic patients and a comparison group of 61 healthy subjects. The results indicated increased as well as decreased brain functions in schizophrenic patients compared to the control group depending on the task difficulty and the performance: during the attention task (0-back), which served as control condition, behavioral responses of patients and healthy subjects hardly differed but BOLD responses were considerably enhanced in schizophrenic patients. With increasing task difficulty differences between groups in BOLD responses diminished whereas behavioral deficits of patients increased. The examination of attention-independent working memory-functions (2- vs. 0-back) produced hypoactivations in patients, especially in frontal, temporal and subcortical brain regions. Furthermore, positive symptoms were associated with parietal dysfunctions. Behavioral performance and neural responses of unaffected relatives of schizophrenic patients were intermediate between schizophrenic patients and controls indicating slight brain dysfunctions. In addition, compensatory strategies were demonstrated. These findings suggest that the genetic risk for schizophrenia is accompanied by neural inefficiency which is associated with cognitive deficits, especially in difficult tasks.

Neurocognitive allied phenotypes for schizophrenia and bipolar disorder

Psychiatric disorders are genetically complex and represent the end product of multiple biological and social factors. Links between genes and disorder-related abnormalities can be effectively captured via assessment of phenotypes that are both associated with genetic effects and potentially contributory to behavioral abnormalities. Identifying intermediate or allied phenotypes as a strategy for clarifying genetic contributions to disorders has been successful in other areas of medicine and is a promising strategy for identifying susceptibility genes in complex psychiatric disorders. There is growing evidence that schizophrenia and bipolar disorder, rather than being wholly distinct disorders, share genetic risk at several loci. Further, there is growing evidence of similarity in the pattern of cognitive and neurobiological deficits in these groups, which may be the result of the effects of these common genetic factors. This review was undertaken to identify patterns of performance on neurocognitive and affective tasks across probands with schizophrenia and bipolar disorder as well as unaffected family members, which warrant further investigation as potential intermediate trait markers. Available evidence indicates that measures of attention regulation, working memory, episodic memory, and emotion processing offer potential for identifying shared and illness-specific allied neurocognitive phenotypes for schizophrenia and bipolar disorder. However, very few studies have evaluated neurocognitive dimensions in bipolar probands or their unaffected relatives, and much work in this area is needed.