Identical Pairs Version Research Articles

Practice Effects and Test-Retest Reliability of the Continuous Performance Test, Identical Pairs Version in Patients with Schizophrenia over Four Serial Assessments.

The purposes of this study were to examine the practice effects and test-retest reliability of the Continuous Performance Test, Identical Pairs version (CPT-IP) over four serial assessments in patients with schizophrenia. Fifty-six patients with schizophrenia were assessed with the CPT-IP four times, once per week. The CPT-IP contains four indices: "2-digit score," "3-digit score," "4-digit score," and "total score." The four indices showed trivial-to-small practice effects (Cohen's d=-0.13-0.24), good-to-excellent test-retest reliability (ICC=0.62-0.88), and unacceptable random measurement error (MDC%=33.8%-110.8%). The total score had the best reliability among the four indices. Although practice effects of the four indices all appeared cumulative, all four CPT-IP indices reached a plateau after the second assessment. These results indicate that clinicians should interpret the change scores of the CPT-IP conservatively and use the total-score index in their routine repeated assessments.

Relationships between intra-individual variability and subclinical psychosis

Extensive research indicates that elevated intra-individual variability (IIV) of reaction time is associated with subclinical psychosis, as well as clinically diagnosed psychotic disorder. However, findings regarding the details of this relationship are equivocal. In particular, it is unknown whether associations between elevated IIV and subclinical psychosis are specific to certain psychotic symptoms or to complex reaction time tasks. Data from 492 undergraduates from the University of Otago were used to address this issue. Schizotypy and psychotic-like experiences (PLE) were assessed via interview and questionnaire, and participants completed both a simple reaction time (SRT) task and a continuous performance task–identical pairs version (CPT-IP). The individual standard deviation and coefficient of variation (ICV) were used as measures of IIV. Participants reporting PLE were more likely to have elevated ICV on the CPT-IP. These associations were specific to paranoid psychotic experiences, and to the suspiciousness subscale of the Schizotypal Personality Questionnaire. There were also weak associations between SRT ICV and PLE. The inclusion of a battery of reaction time tasks assessing different aspects of cognitive control is suggested for future research, and the findings are discussed in relation to theoretical approaches to paranoia and delusions.

The effects of carbamazepine on prefrontal activation in manic youth with bipolar disorder

This preliminary study investigated the neurofunctional effects of carbamazepine-extended release (XR) treatment in 11 manic youth with bipolar disorder during performance of a sustained attention task, the Continuous Performance Task – Identical Pairs version (CPT-IP), during functional magnetic resonance imaging (fMRI). All patients underwent baseline fMRI, and 10 patients were scanned again at endpoint. Nine demographically matched healthy youth, who were scanned once, served as controls. Carbamazepine-XR treatment was associated with normalization of activation in right Brodmann area 10 (BA). These results suggest that carbamazepine-XR treatment may correct prefrontal dysfunction in adolescent mania.

Is There an Association between Advanced Paternal Age and Endophenotype Deficit Levels in Schizophrenia?

The children of older fathers have increased risks of developing schizophrenia spectrum disorders, and among those who develop these disorders, those with older fathers present with more severe clinical symptoms. However, the influence of advanced paternal age on other important domains related to schizophrenia, such as quantitative endophenotype deficit levels, remains unknown. This study investigated the associations between paternal age and level of endophenotypic impairment in a well-characterized family-based sample from the Consortium on the Genetics of Schizophrenia (COGS). All families included at least one affected subject and one unaffected sibling. Subjects met criteria for schizophrenia (probands; n = 293) or were unaffected first-degree siblings of those probands (n = 382). Paternal age at the time of subjects’ birth was documented. Subjects completed a comprehensive clinical assessment and a battery of tests that measured 16 endophenotypes. After controlling for covariates, potential paternal age–endophenotype associations were analyzed using one model that included probands alone and a second model that included both probands and unaffected siblings. Endophenotype deficits in the Identical Pairs version of the 4-digit Continuous Performance Test and in the Penn Computerized Neurocognitive Battery verbal memory test showed significant associations with paternal age. However, after correcting for multiple comparisons, no endophenotype was significantly associated with paternal age. These findings suggest that factors other than advanced paternal age at birth may account for endophenotypic deficit levels in schizophrenia.

Bases cerebrales de la atención sostenida y la memoria de trabajo: un estudio de resonancia magnética funcional basado en el Continuous Performance Test

One of the most used paradigms in the study of attention is the Continuous Performance Test (CPT). The identical pairs version (CPT-IP) has been widely used to evaluate attention deficits in developmental, neurological and psychiatric disorders. However, the specific locations and the relative distribution of brain activation in networks identified with functional imaging, varies significantly with differences in task design. To design a task to evaluate sustained attention using functional magnetic resonance imaging (fMRI), and thus to provide data for research concerned with the role of these functions. Forty right-handed, healthy students (50% women; age range: 18-25 years) were recruited. A CPT-IP implemented as a block design was used to assess sustained attention during the fMRI session. The behavioural results from the CPT-IP task showed a good performance in all subjects, higher than 80% of hits. fMRI results showed that the used CPT-IP task activates a network of frontal, parietal and occipital areas, and that these are related to executive and attentional functions. In relation to the use of the CPT to study of attention and working memory, this task provides normative data in healthy adults, and it could be useful to evaluate disorders which have attentional and working memory deficits.

The effects of acute tryptophan depletion on impulsivity and mood in adolescents engaging in non‐suicidal self‐injury

Non-suicidal self-injury (NSSI) is associated with impaired emotion regulation and impulsivity. Low serotonin (5-hydroxytryptamine) function is associated with NSSI, impaired emotion regulation and impulsivity. We investigated the effects of experimentally lowered 5-hydroxytryptamine activity, via acute tryptophan depletion (ATD), on impulsive action, reflection impulsivity and mood in female adolescents engaging in NSSI. Thirty-two female adolescents engaging in NSSI participated in a parallel group ATD study. Following ATD, impulsive action was assessed using the Continuous Performance Test, Identical Pairs Version. Reflection impulsivity was assessed using the Matching Familiar Figures Test. Mood-lowering was examined using the Profile of Mood States. Following ATD, the participants showed an impulsive response style (as reflected in their low β) and increased attentional capacity (as reflected in their elevated d'). ATD did not affect reflection impulsivity or mood. Acute tryptophan depletion caused an impulsive response style and increased attentional capacity. Importantly, the findings suggest that low serotonin function is a vulnerability among female adolescents for engaging in NSSI when in emotional distress.

A developmental look at the attentional system in the at risk and first episode of psychosis: Age related changes in attention along the psychosis spectrum

Introduction. Neurodevelopmental processes of adolescence, when superimposed on a vulnerable brain, may produce additive effects reflecting the subthreshold psychotic symptoms, cognitive, and functional deterioration that are the hallmark of the early stages of schizophrenia. Methods. As part of a longitudinal study, we investigated Continuous Performance Task, Identical Pairs Version (CPT-IP) performance in a sample of 301 participants (at risk for psychosis: 109; first episode–FE: 90; and controls: 102). Performance across groups was compared using d' of fast and slow, spatial and verbal conditions over two time points. Age effects were investigated using a regression model. Results. Across all four CPT-IP conditions FE patients performed significantly worse than controls while AR individuals significantly differed from healthy subjects in the verbal condition. Age-related performance associations across groups significantly differed in the slow verbal condition because the FE sample did not show a significant association with increasing age like the AR and NC samples. CPT performance was stable over time. Conclusions. Sustained attention in the putative prodrome of psychosis is not only impaired but associated with age. Research focusing on cognitive and neurobiological age-related changes can help to address fundamental questions about the nature of the disorder, including whether the underlying pathophysiology of early psychosis is static or deteriorating.

Evaluation of Factors Affecting Continuous Performance Test Identical Pairs Version Score of Schizophrenic Patients in a Japanese Clinical Sample

Aim. Cognitive impairment in schizophrenia strongly relates to social outcome and is a good candidate for endophenotypes. When we accurately measure drug efficacy or effects of genes or variants relevant to schizophrenia on cognitive impairment, clinical factors that can affect scores on cognitive tests, such as age and severity of symptoms, should be considered. To elucidate the effect of clinical factors, we conducted multiple regression analysis using scores of the Continuous Performance Test Identical Pairs Version (CPT-IP), which is often used to measure attention/vigilance in schizophrenia. Methods. We conducted the CPT-IP (4-4 digit) and examined clinical information (sex, age, education years, onset age, duration of illness, chlorpromazine-equivalent dose, and Positive and Negative Symptom Scale (PANSS) scores) in 126 schizophrenia patients in Japanese population. Multiple regression analysis was used to evaluate the effect of clinical factors. Results. Age, chlorpromazine-equivalent dose, and PANSS-negative symptom score were associated with mean d′ score in patients. These three clinical factors explained about 28% of the variance in mean d′ score. Conclusions. As conclusion, CPT-IP score in schizophrenia patients is influenced by age, chlorpromazine-equivalent dose and PANSS negative symptom score.

Has an important test been overlooked? Closure flexibility in schizophrenia

Deficits in visual processing are now recognized as a core feature of schizophrenia. In the 1940s, Louis Thurstone developed a series of tests designed to evaluate specific aspects of visual perceptual processing including the Closure Flexibility Test (CFT), which was designed to measure “the ability to hold a configuration in mind despite distraction.” The present study evaluated patients' performance on this task and its relationship to other tests of neuropsychological function, particularly to a measure of sustained visual attention. Thirty-nine patients with schizophrenia or schizoaffective disorder and 40 controls participated. The CFT was administered both in its original form (10min) and also in a briefer form (3min) in which only a portion of stimuli were given. Patients showed highly significant large effect-size deficits on both the original (d=1.6) and brief (d=1.2) CFT. Between-group deficits in performance survived co-variation for IQ. In addition, the CFT score was significantly related to performance on the MATRICS measure of attention/vigilance, the Continuous Performance Test—Identical Pairs version (CPT-IP). This correlation remained significant even after controlling for non-specific intercorrelations among neurocognitive measures. Results confirm the severity of early visual processing deficits in schizophrenia. In addition, the CFT is a brief, easy to administer alphabet-independent, paper-and-pencil test with established psychometric properties that may be useful as an index of the sustained visual attention construct in schizophrenia.

COMT Val158Met Polymorphism is Associated with Cognitive Flexibility in a Signal Discrimination Task in Schizophrenia

Associations between the well-known functional single nucleotide polymorphism Val (158)Met in the gene encoding catechol- O-methyltransferase (COMT) and cognitive do-mains affected in schizophrenia are inconsistent regarding directionality and specific impact and call for a more fundamental cognitive endophenotype. Recent studies suggest that the COMT genotype contributes to cognitive flexibility, a fundamental cognitive ability that potentially influences an individual's performance in a variety of other neurocognitive tasks. We investigated the association between COMT Val (158)Met genotype and cognitive flexibility as assessed by signal discrimination in the Continuous Performance Test - Identical Pairs version in a cohort of 111 German schizophrenic patients. COMT genotype was significantly associated with signal discrimination index d' in schizophrenia. The Val/Val genotype was associated with the highest and the Met/Met genotype with the lowest scores; heterozygous individuals displayed an intermediate performance. Our data suggest that allelic variation at the COMT Val (158)Met locus may influence signal discrimination capacity in schizophrenia and confirm that Val loading, probably due to decreased prefrontal dopamine availability, is associated with greater cognitive flexibility, which in turn may influence other cognitive measures that have been associated with COMT to date.

Neurocognitive performances in participants of at-risk mental state for schizophrenia and in first-episode patients

As suggested by the neurodevelopmental model, neurocognitive disturbances are core features of schizophrenia spectrum disorders. The aim of the present study was to explore the neurocognitive performance of symptomatically defined high-risk participants as well as first-episode patients on tests of verbal memory, executive functioning, working memory, and attention. The sample consisted of 54 participants at risk for schizophrenia and 37 patients with a first episode of psychosis. The high-risk group exhibited a similar cognitive performance profile to that of the first-episode participants when compared with normative data. The neurocognitive functioning of both patient groups were within standard average range at most of the cognitive domains. Moreover the intellectual functioning of both groups was within higher average level, while decreased “hit rates” could be observed within both subtests “Figures” and “Symbols” of the Continuous Performance Test–Identical Pairs Version (CPT-IP) in the group of first-episode patients. Direct comparison between the clinical groups did show increasing impairments of these parameters in first-episode patients compared to high-risk participants. Results suggest that high-risk participants do perform at average neurocognitive performance levels at all tested domains compared with normative data. Compared to norm values first-episode patients showed decreased attention abilities.

The use and meaning of the continuous performance test in schizophrenia

AbstractThe continuous performance test (CPT) is a behavioural assessment of attentional modulation of the motor system (Rosvold et al., 1956). It has firstly been used in patients with brain injuries and then applied to assess sustained attention and vigilance in epilepsy, brain tumor, dementia, schizophrenia and other psychiatric diseases, such as attention-deficit hyperactivity disorder (ADHD) and anxiety disorders (Rosvold et al., 1956; Honey et al., 2005; Kanaka et al., 2008). There are several versions of the test. For instance, the X-CPT version presents randomly different stimuli and subjects are asked to push a button only on presentation of the target stimuli (X). In the AX-CPT version, the subjects are required to push the button only when a cue stimulus is presented before the target one (A before X). The following items are measured for the X and AX tasks: omission errors (number of times subjects fail to respond to target stimulation), commission errors (number of times subjects respond to non target stimulation), average reaction time and coefficient of variance for both correct reactions and commission errors (Suwa et al., 2004). There are other versions, such as the CPT-not X version where the subjects are asked not to push a button when the target stimulus (X) is presented; the Degraded Stimuli (DS)-CPT (Nuechterlein, 1983); the CPT playing card version (Rutschmann et al., 1977); and the CPT Identical Pairs version (Cornblatt et al., 1988), which is a more difficult task prepared to assess high risk population. Interestingly, the Identical Pairs version has been included in the Matrics neurocognitive assessment, a consensus cognitive battery for clinical trials of cognition in schizophrenia (Nuechterlein et al., 2008).

Attentional deficits in cocaine-dependent patients: Converging behavioral and electrophysiological evidence

Although there are several reports of patients with cocaine dependence displaying cognitive deficits, the nature of their information processing deficits is not well characterized. In the present study, the attentional performance of cocaine-dependent patients ( n = 14) was examined and compared with that of healthy control individuals ( n = 15). Attention was assessed using an auditory oddball event-related task as well as the Continuous Performance Test (CPT, Identical Pairs version). The cocaine-dependent group displayed P300 amplitude reduction compared to controls. The group difference in P300 response latency did not reach significance. On the CPT, the cocaine-dependent patients displayed significantly poorer discriminability and greater errors of commission than the controls. There was a positive correlation between performance on the oddball event-related task and performance on the CPT. This investigation provides converging behavioral and electrophysiological evidence of attentional deficits in cocaine-dependent patients.

High-dose galantamine augmentation inferior to placebo on attention, inhibitory control and working memory performance in nonsmokers with schizophrenia

Dysfunction in the neuronal nicotinic acetylcholine receptor (nAChR) system has been implicated in the pathophysiology of schizophrenia, and it has been postulated that treatments that increase nAChR activity may improve symptoms of the disorder. We investigated the effects of the acetylcholinesterase inhibitor and allosteric nAChR modulator, galantamine, on cognitive performance and clinical symptoms when added to a stable antipsychotic medication regimen in nonsmoking outpatients with schizophrenia in a double-blind, placebo-controlled, parallel-group design. Participants were randomized to receive either galantamine ( n = 10) up to 32 mg/day or identical placebo ( n = 10) for 8 weeks and completed a cognitive battery at baseline and week 8 and clinical scales at baseline, week 4 and week 8. The primary outcome measure was attentional performance as measured by the d' measure in the Continuous Performance Test — Identical Pairs (CPT-IP) Version. Contrary to our hypothesis, galantamine treatment was associated with inferior performance on the CPT-IP, on the three-card Stroop task, and on the Letter–Number Span task without reordering. Galantamine had no effect on clinical symptoms. In summary, galantamine treatment, at a dose of 32 mg/day, was well tolerated but was not effective as an adjunctive treatment for cognitive deficits in stable nonsmokers with schizophrenia.

Cognitive MR spectroscopy of anterior cingulate cortex in ADHD: Elevated choline signal correlates with slowed hit reaction times

The anterior cingulate cortex (ACC) plays a major role in modulating executive control of attention. Here, 15 medication-naı¨ve patients with attention deficit/hyperactivity disorder (ADHD) and 10 carefully matched healthy controls were studied with 2D 1H-magnetic resonance spectroscopic imaging (MRSI) of the ACC [Brodmann areas 24b′-c′ and 32′]. Attentional skills were assessed using the identical pairs version of the continuous performance task (CPT-IP). Analysis of regional brain spectra revealed a significantly increased signal of choline-containing compounds (Ch) in the ACC of ADHD patients ( p < 0.05). Across and within groups, the Ch signal showed high correlations with slowed hit reaction times on the CPT-IP. No group differences in N-acetyl-aspartate (NAA) and creatine (tCr) were detectable. The combination of performance deficits and elevated Ch levels in the ACC supports the hypothesis that subtle structural abnormalities underlie the functional alterations in ACC activation previously observed in ADHD patients.

The Effects of Transdermal Nicotine on Cognition in Nonsmokers with Schizophrenia and Nonpsychiatric Controls

Abundant evidence indicates that the neuronal nicotinic acetylcholine receptor (nAChR) system is integral to regulation of attentional processes and is dysregulated in schizophrenia. Nicotinic agonists may have potential for the treatment of cognitive impairment in this disease. This study investigated the effects of transdermal nicotine on attention in individuals with schizophrenia (n=28) and healthy controls (n=32). All participants were nonsmokers in order to eliminate confounding effects of nicotine withdrawal and reinstatement that may occur in the study of smokers. Subjects received 14 mg transdermal nicotine and identical placebo in a randomized, placebo-controlled, crossover design. A cognitive battery was conducted before and 3 h after each patch application. The primary outcome measure was performance on the Continuous Performance Test Identical Pairs (CPT-IP) Version. Nicotine significantly improved the performance on the CPT-IP as measured by hit reaction time, hit reaction time standard deviation and random errors in both groups. In addition, nicotine reduced commission errors on the CPT-IP and improved the performance on a Card Stroop task to a greater extent in those with schizophrenia vs controls. In summary, nicotine improved attentional performance in both groups and was associated with greater improvements in inhibition of impulsive responses in subjects with schizophrenia. These results confirm previous findings that a single dose of nicotine improves attention and suggest that nicotine may specifically improve response inhibition in nonsmokers with schizophrenia.

Gender differences, impulsivity and attention measures in BPD patients

Background and aims:Despite the intense study on impulsivity in BPD, little attention has been given to the relationship between gender, impulsivity and BPD. Previous findings are inconsistent and there is a lack of specific research.The purpose of this study is to examine the differences between man and women with BDP in different impulsivity measures.Method:We examined the gender differences in 45 subjects recruited in a psychiatric unit, in which 33 (73,3%) were women and 12 (26,7%) were men. Mean age of the study sample was 28.9 years old (SD= 1.04). No differences were found in socio-demographic variables between men and women. In order to establish a BDP diagnose the Structured Clinical Interview for DSM-IV Axis II Personality Disorder (SCID-II) was used. Impulsivity was assessed with the Barrat Impulsivity Scale (BIS-11) and the Continuous Performance Test identical pairs version (CPT-IP).Results:We found significant gender differences in BIS scores. Men have scored higher than women in all BIS scores, especially in the second-order factor of nonplanning impulsiveness.In CPT-IP results there were also significant differences between men and women performance. Men made a higher number of correct answers (hits) and a higher number of false alarms (commission errors) than women. Also, men had a significant higher score in the d index (attentional capacity) than women.Conclusion:Gender differences influence the performance in laboratorial and psychometric measures of impulsivity in BPD subjects. This pattern of impulsivity is consistent with the attentional performance in these subjects.

Deficits on the continuous performance test within the schizophrenia spectrum and the mediating effects of family history of schizophrenia.

Individuals with schizophrenia spectrum personality disorders (SSPD) and schizophrenia show similar cognitive impairments. The authors examined the contributions of SSPD symptoms and familial risk for schizophrenia to impairments on the Continuous Performance Test--Identical Pairs Version. Participants included 103 schizophrenia patients, 66 first-degree relatives (29 SSPD), and 103 community controls (26 SSPD) screened for family history of psychosis. Patients and SSPD relatives performed significantly worse than non-SSPD relatives and SSPD and non-SSPD community controls. No differences in performance were observed among non-SSPD relatives and SSPD and non-SSPD community controls. Results suggest a continuum in which risk for schizophrenia-related cognitive impairments is highest among patients and SSPD relatives, intermediate among non-SSPD relatives, and lowest among SSPD and non-SSPD community controls. Results suggest that SSPD in the absence of a family history of psychosis may be a phenocopy.

Effect of COMT Val158Met Polymorphism on the Continuous Performance Test, Identical Pairs Version: Tuning Rather Than Improving Performance

It has been suggested that variation in catechol O-methyltransferase (COMT) activity associated with variation in COMT Val158Met genotypes may result in enhanced or reduced cognitive performance, depending on whether the phenotype requires cognitive stability or cognitive flexibility. The authors' goal was to determine whether, in confirmation of this prediction, performance on a measure of cognitive stability would be associated with Met loading. COMT genotyping was investigated in relation to a measure of reaction time variability on the Continuous Performance Test, Identical Pairs Version, in a large and representative sample of 527 young men (mean age=21 years). Met loading was associated with reduced reaction time variability. Met genotype loading may confer enhanced "tuning" or greater stability in performance, possibly by stabilizing active neural representations in the prefrontal cortex during tasks involving working memory.

Sustained attention in young people at high risk of psychosis does not predict transition to psychosis

Early detection of imminent psychosis allows for the possibility of interventions to prevent onset, or to minimise severity and disability. It also has potential to enhance knowledge of the factors important in the etiology of psychotic illnesses. Neurocognitive deficits are well documented in psychotic illnesses and there is evidence to suggest that such deficits are present in individuals long before they develop the illness. Further, it has been proposed that such impairments may indicate an underlying predisposition to develop psychosis and may thus be described as ‘vulnerability indicators’. This study aimed to investigate the proposed vulnerability indicator of impaired sustained attention in young people thought to be at ultra high-risk of developing psychosis imminently to see whether it would improve the prediction of psychosis in this group. The Continuous Performance Test – Identical Pairs (CPT-IP) version performance of an ultra high-risk group (UHR, N = 70) was compared with that of a healthy comparison group (NC, N = 51) and a first-episode psychosis group (FEP, N = 32). The UHR group exhibited performance deficits compared to the NC group and performed at a level similar to that of the FEP group. However, within the UHR group, those who developed psychosis within the timeframe of the study did not differ from those who did not develop psychosis on their CPT-IP performance. These results support sustained attention as an indicator of vulnerability to psychosis, but suggest that CPT-IP performance does not help to predict transition to psychosis in an ultra high-risk group.