Attentional abilities and measures of schizotypy: their variation and covariation in schizophrenic patients, their siblings, and normal control subjects

Neurocognitive functioning in adult and adolescent offspring of parents with schizophrenia

INTRODUCTION

Neurocognitive deficits have been proposed as endophenotypes for schizophrenia. Although neurocognitive functioning has been studied extensively in first-degree relatives of schizophrenia patients at single time points, little is known about the change or continuity in deficits across development.

METHOD

The longitudinal sample was composed of 86 nonpsychotic participants who had a parent with schizophrenia (n = 28), a parent with a nonschizophrenia mental disorder (n = 31) or parents without mental illness (n = 27). Executive functioning (EF) was assessed during adolescence (M = 18 years) and adulthood (M = 32 years); attention and memory were assessed at adulthood.

RESULTS

The schizophrenia group, as adults, showed deficits in attention and memory relative to the no mental illness group. Only on one memory task did the schizophrenia group perform more poorly than the other mental illness group. Executive functioning improved with age for all three groups on Wisconsin Card Sorting Test perseverative errors; the rate of improvement was significantly slower for the schizophrenia and the other mental illness groups, compared to the no mental illness group. Stability in EF functioning over the 16-year period, measured by intraclass correlations, was low.

CONCLUSIONS

Adults at familial risk for schizophrenia showed deficits in neurocognitive functioning. The similarity of performance between those whose parents had schizophrenia and those whose parents had other mental illness, in all but the measures of memory, raises the question as to whether the neurocognitive functions examined are endophenotypes of vulnerability to schizophrenia specifically. Modest stability of EF and improved performance with age may reflect cortical maturation during early adulthood.

Psychiatric framing affects positive but not negative schizotypy scores in psychology and medical students

When testing risk for psychosis, we regularly rely on self-report questionnaires. Yet, the more that people know about this condition, the more they might respond defensively, in particular with regard to the more salient positive symptom dimension. In two studies, we investigated whether framing provided by questionnaire instructions might modulate responses on self-reported positive and negative schizotypy. The O-LIFE (UK study) or SPQ (New Zealand study) questionnaire was framed in either a "psychiatric", "creativity", or "personality" (NZ only) context. We tested psychology students (without taught knowledge about psychosis) and medical students (with taught knowledge about psychosis; UK only). We observed framing effects in psychology students in both studies: positive schizotypy scores were lower after the psychiatric compared to the creativity instruction. However, schizotypy scores did not differ between the creativity and personality framing conditions, suggesting that the low scores with psychiatric framing reflect defensive responding. The same framing effect was also observed in medical students, despite their lower positive schizotypy scores overall. Negative schizotypy scores were not affected by framing in either study. These results highlight the need to reduce response biases when studying schizotypy, because these might blur schizotypy-behaviour relationships.

A study of physical anhedonia as a trait marker in schizophrenia

BACKGROUND

Inability to define the heritable phenotype might be a reason for failure to replicate results in psychiatric genetics. Hence, the use of a candidate symptom approach to identify more homogeneous forms of diseases among affected individuals and subclinical traits among first-degree relatives (FDRs) may increase genetic validity. The objective of the present study was to determine whether physical anhedonia can be used as a marker for individuals at risk of schizophrenia.

MATERIALS AND METHODS

Physical anhedonia scores (measured using Revised Physical Anhedonia Scale [rPAS]) were compared across thirty remitted schizophrenic patients, thirty of their unaffected FDRs, and thirty healthy controls. We compared anhedonia scores among the three main groups using one-way ANOVA.

RESULTS

Physical anhedonia (rPAS) scores of the schizophrenic patient group were significantly higher than that of their FDRs and controls both, and physical anhedonia (rPAS) scores of FDRs were significantly higher than that of healthy controls (F = 115.33, P < 0.001). The subgroups did not differ on various other clinical characteristics.

CONCLUSION

Our data suggest that physical anhedonia is a candidate symptom for schizophrenia.

Reverse translated and gold standard continuous performance tests predict global cognitive performance in schizophrenia

Attentional dysfunction contributes to functional impairments in schizophrenia (SZ). Sustained attention is typically assessed via continuous performance tasks (CPTs), though many CPTs have limited cross-species translational validity and place demands on additional cognitive domains. A reverse-translated 5-Choice Continuous Performance Task (5C-CPT) for human testing-originally developed for use in rodents-was designed to minimize demands on perceptual, visual learning, processing speed, or working memory functions. To-date, no studies have validated the 5C-CPT against gold standard attentional measures nor evaluated how 5C-CPT scores relate to cognition in SZ. Here we examined the relationship between the 5C-CPT and the CPT-Identical Pairs (CPT-IP), an established and psychometrically robust measure of vigilance from the MATRICS Consensus Cognitive Battery (MCCB) in a sample of SZ patients (n = 35). Relationships to global and individual subdomains of cognition were also assessed. 5C-CPT and CPT-IP measures of performance (d-prime) were strongly correlated (r = 0.60). In a regression model, the 5C-CPT and CPT-IP collectively accounted for 54% of the total variance in MCCB total scores, and 27.6% of overall cognitive variance was shared between the 5C-CPT and CPT-IP. These results indicate that the reverse translated 5C-CPT and the gold standard CPT-IP index a common attentional construct that also significantly overlaps with variance in general cognitive performance. The use of simple, cross-species validated behavioral indices of attentional/cognitive functioning such as the 5C-CPT could accelerate the development of novel generalized pro-cognitive therapeutics for SZ and related neuropsychiatric disorders.

Improvements and important considerations for the 5-choice serial reaction time task-An effective measurement of visual attention in rats

BACKGROUND

The 5-choice serial reaction time task (5-CSRTT) is an automated operant conditioning task that measures rodent attention. The task allows the measurement of several parameters such as response accuracy, speed of processing, motivation, and impulsivity. The task has been widely used to investigate attentional processes in rodents for attention deficit and hyperactivity disorder and has expanded to other illnesses such as Alzheimer's disease, depression, and schizophrenia.

NEW METHOD

The 5-CSRTT is accompanied with two significant caveats: a time intensive training period and largely varied individual rat capability to learn and perform the task. Here we provide a regimented acquisition protocol to enhance training for the 5-CSRTT and discuss important considerations for researchers using the 5-CSRTT.

RESULTS

We offer guidelines to ensure that inferences on performance in the 5-CSRTT are in fact a result of experimental manipulation rather than training differences, or individual animal capability. According to our findings only rats that have been trained successfully within a limited time frame should be used for the remainder of the study.

COMPARISON WITH EXISTING METHOD(S)

Currently the 5-CSRTT employs a training period of variable duration and procedure, and its inferences on attention must overcome heterogeneous innate animal differences.

CONCLUSIONS

The 5-CSRTT offers valuable and valid insights on various rodent attentional processes and their translation to the underpinnings of illnesses such as schizophrenia. The recommendations made here provide important criteria to ensure inferences made from this task are in fact relevant to the attentional processes being measured.

The NEWMEDS rodent touchscreen test battery for cognition relevant to schizophrenia

RATIONALE

The NEWMEDS initiative (Novel Methods leading to New Medications in Depression and Schizophrenia, http://www.newmeds-europe.com ) is a large industrial-academic collaborative project aimed at developing new methods for drug discovery for schizophrenia. As part of this project, Work package 2 (WP02) has developed and validated a comprehensive battery of novel touchscreen tasks for rats and mice for assessing cognitive domains relevant to schizophrenia.

OBJECTIVES

This article provides a review of the touchscreen battery of tasks for rats and mice for assessing cognitive domains relevant to schizophrenia and highlights validation data presented in several primary articles in this issue and elsewhere.

METHODS

The battery consists of the five-choice serial reaction time task and a novel rodent continuous performance task for measuring attention, a three-stimulus visual reversal and the serial visual reversal task for measuring cognitive flexibility, novel non-matching to sample-based tasks for measuring spatial working memory and paired-associates learning for measuring long-term memory.

RESULTS

The rodent (i.e. both rats and mice) touchscreen operant chamber and battery has high translational value across species due to its emphasis on construct as well as face validity. In addition, it offers cognitive profiling of models of diseases with cognitive symptoms (not limited to schizophrenia) through a battery approach, whereby multiple cognitive constructs can be measured using the same apparatus, enabling comparisons of performance across tasks.

CONCLUSION

This battery of tests constitutes an extensive tool package for both model characterisation and pre-clinical drug discovery.

Investigating the empirical support for therapeutic targets proposed by the temporal experience of pleasure model in schizophrenia: A systematic review

BACKGROUND

Anhedonia and amotivation are substantial predictors of poor functional outcomes in people with schizophrenia and often present a formidable barrier to returning to work or building relationships. The Temporal Experience of Pleasure Model proposes constructs which should be considered therapeutic targets for these symptoms in schizophrenia e.g. anticipatory pleasure, memory, executive functions, motivation and behaviours related to the activity. Recent reviews have highlighted the need for a clear evidence base to drive the development of targeted interventions.

OBJECTIVE

To review systematically the empirical evidence for each TEP model component and propose evidence-based therapeutic targets for anhedonia and amotivation in schizophrenia.

METHOD

Following PRISMA guidelines, PubMed and PsycInfo were searched using the terms "schizophrenia" and "anhedonia". Studies were included if they measured anhedonia and participants had a diagnosis of schizophrenia. The methodology, measures and main findings from each study were extracted and critically summarised for each TEP model construct.

RESULTS

80 independent studies were reviewed and executive functions, emotional memory and the translation of motivation into actions are highlighted as key deficits with a strong evidence base in people with schizophrenia. However, there are many relationships that are unclear because the empirical work is limited by over-general tasks and measures.

CONCLUSIONS

Promising methods for research which have more ecological validity include experience sampling and behavioural tasks assessing motivation. Specific adaptations to Cognitive Remediation Therapy, Cognitive Behavioural Therapy and the utilisation of mobile technology to enhance representations and emotional memory are recommended for future development.

Correlations between psychometric schizotypy, scan path length, fixations on the eyes and face recognition

Psychometric schizotypy in the general population correlates negatively with face recognition accuracy, potentially due to deficits in inhibition, social withdrawal, or eye-movement abnormalities. We report an eye-tracking face recognition study in which participants were required to match one of two faces (target and distractor) to a cue face presented immediately before. All faces could be presented with or without paraphernalia (e.g., hats, glasses, facial hair). Results showed that paraphernalia distracted participants, and that the most distracting condition was when the cue and the distractor face had paraphernalia but the target face did not, while there was no correlation between distractibility and participants' scores on the Schizotypal Personality Questionnaire (SPQ). Schizotypy was negatively correlated with proportion of time fixating on the eyes and positively correlated with not fixating on a feature. It was negatively correlated with scan path length and this variable correlated with face recognition accuracy. These results are interpreted as schizotypal traits being associated with a restricted scan path leading to face recognition deficits.

Attention/vigilance in schizophrenia: performance results from a large multi-site study of the Consortium on the Genetics of Schizophrenia (COGS)

Attention/vigilance impairments are present in individuals with schizophrenia across psychotic and remitted states and in their first-degree relatives. An important question is whether deficits in attention/vigilance can be consistently and reliably measured across sites varying in many participant demographic, clinical, and functional characteristics, as needed for large-scale genetic studies of endophenotypes. We examined Continuous Performance Test (CPT) data from phase 2 of the Consortium on the Genetics of Schizophrenia (COGS-2), the largest-scale assessment of cognitive and psychophysiological endophenotypes relevant to schizophrenia. The CPT data from 2251 participants from five sites were examined. A perceptual-load vigilance task (the Degraded Stimulus CPT or DS-CPT) and a memory-load vigilance task (CPT-Identical Pairs or CPT-IP) were utilized. Schizophrenia patients performed more poorly than healthy comparison subjects (HCS) across sites, despite significant site differences in participant age, sex, education, and racial distribution. Patient-HCS differences in signal/noise discrimination (d') in the DS-CPT varied significantly across sites, but averaged a medium effect size. CPT-IP performance showed large patient-HCS differences across sites. Poor CPT performance was independent of or weakly correlated with symptom severity, but was significantly associated with lower educational achievement and functional capacity. Current smoking was associated with poorer CPT-IP d'. Patients taking both atypical and typical antipsychotic medication performed more poorly than those on no or atypical antipsychotic medications, likely reflecting their greater severity of illness. We conclude that CPT deficits in schizophrenia can be reliably detected across sites, are relatively independent of current symptom severity, and are related to functional capacity.

The continuous performance test, identical pairs: norms, reliability and performance in healthy controls and patients with schizophrenia in Singapore

AIM

To provide normative values for the healthy ethnic Chinese Singaporean population and a large sample of patients with schizophrenia for the Continuous Performance Task-Identical Pairs (CPT-IP). Participants Data were collected on 1011 healthy ethnic Chinese and 654 patients diagnosed with schizophrenia, all between 21 and 55 years of age.

METHODS

Data were stratified by age and gender. The effects of age, gender and education were explored in patients and controls. Performance indices were assessed in their ability to predict group inclusion. Controls' performance was compared with that reported in a US sample.

RESULTS

Performance was affected by age, sex, and education, with youth, male sex and higher education providing a performance advantage. Patients' performance was lower than controls' by more than 1 standard deviation, with the 3-digit d' score most significantly discriminating between controls and patients. The effects of socio-demographic factors on performance were in line with those conducted in the US and previously reported in the literature.

CONCLUSIONS

This is the largest norming study ever conducted on the CPT-IP. It will enable investigators and clinicians to select appropriate indices to assess severity of cognitive decline and/or evaluate cognitive remediation therapy outcomes after taking into account age, gender and education factors.

Assessing long-term test-retest reliability of the CPT-IP in schizophrenia

Background

The Continuous Performance Test-Identical Pairs version (CPT-IP) is a well-established measure of sustained attention, and its more challenging versions are particularly suited to detect subtle processing deficits in patients with schizophrenia. However, while there are few longitudinal samples for the CPT-IP, no study has addressed stability for more than two month in patients with schizophrenia. Assessing long-term test-retest reliability of the CPT-IP would facilitate the ability of clinicians to draw conclusions from studies involving interventions as long term cognitive or pharmacological treatments. The present study assessed 12 month test-retest reliability for the two most challenging versions of CPT-IP (4-digit and shapes) in a matched sample of clinically stable schizophrenia outpatients and healthy controls.

Methods

Fifty clinically stable schizophrenia outpatients and 50 healthy controls were assessed with the CPT-IP for the 4-digit and shape conditions. From these, 40 patients and 47 controls were reassessed with an average interval of 12.3 months between test sessions. Test-retest reliability was analyzed with Pearson correlations and results were compared with previous data involving healthy controls and short-term studies in patients with schizophrenia.

Results

Especially d’ and hit rate discriminated well between patients with schizophrenia and healthy controls for both CPT-IP conditions and at both test sessions. Healthy controls demonstrated sufficient long term test-retest correlations of d’, hit rate and reaction time for both the 4-digit and shape conditions. However, in schizophrenia patients, long-term reliability correlations were at best moderate for d’ and hit rate only.

Conclusions

The current study provides further evidence that d’ and hit rate yield consistent cross-sectional discrimination sensitivity. At best moderate long-term test-retest reliability of d’ in schizophrenia outpatients may be not sufficient for practical use of this measure in long term clinical trials.

The crisis of minimal self-awareness in schizophrenia: a meta-analytic review

Disturbances of the minimal self, characterized by abnormal sense of the body, body ownership and agency have been proposed as the phenomenological phenotype of schizophrenia. However, self-disturbances have not been extensively investigated, in part, due to the subjective nature of such processes, and the associated difficulty of studying these phenomena using empirical methodology. Of 115 potential studies on self-awareness in schizophrenia, a total of 25 studies met the inclusion criteria for the meta-analysis comprising 690 patients with schizophrenia and 979 healthy controls. We calculated Hedge's g to obtain a better estimate for the standardized mean difference in small samples. We identified significant basic self-disturbance in schizophrenia, as compared with healthy controls (25 studies, effect size=0.51). Additional comparison of three sub-categories of the sense of body ownership (4 studies, effect size=0.91), the sense of agency (15 studies, effect size=0.49), and self-reported subjective experiences (6 studies, effect size=0.57) also confirmed group differences. The complete set of 25 studies, and the studies in the sub-categories showed the statistical homogeneity of the characteristics. After a correction for potential publication bias using the trim-and-fill method, the main findings for all studies combined remained significant. Overall, patients with schizophrenia showed deficits in the sense of the minimal self, driven by abnormal sense of body ownership and sense of agency. Interestingly, the disturbed sense of agency in schizophrenia suggests an exaggerated self-consciousness rather than a diminished sense of self. Further research that utilizes sophisticated study designs is needed to examine the nature of self-disturbances in schizophrenia.

Neural substrates underlying effort computation in schizophrenia

The lack of initiative, drive or effort in patients with schizophrenia is linked to marked functional impairments. However, our assessment of effort and motivation is crude, relying on clinical rating scales based largely on patient recall. In order to better understand the neurobiology of effort in schizophrenia, we need more rigorous measurements of this construct. In the behavioural neuroscience literature, decades of work has been carried out developing various paradigms to examine the neural underpinnings of an animal's willingness to expend effort for a reward. Here, we shall review this literature on the nature of paradigms used in rodents to assess effort, as well as those used in humans. Next, the neurobiology of these effort-based decisions will be discussed. We shall then review what is known about effort in schizophrenia, and what might be inferred from experiments done in other human populations. Lastly, we shall discuss future directions of research that may assist in shedding light on the neurobiology of effort cost computations in schizophrenia.

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.

Interactive effects of background facial emotion stimulus and target salience on sustained attention performance in schizophrenia

Schizophrenia impairs both facial emotion processing and sustained attention. Through separate studies, it is known that the presence of a task-irrelevant facial stimulus disproportionately interferes with performance, whereas increasing the salience of task stimulus improves performance during a sustained attention task in patients with schizophrenia. We wished to investigate a potential interaction effect of background facial emotion expression (black and white happy faces vs. grey oval) and target stimulus salience (bright white vs. grey) using the Continuous Performance Test-Identical Pairs version (CPT-IP) in patients with schizophrenia. Thirty-six patients with schizophrenia and 28 healthy control subjects completed 4 different versions of the CPT-IP. We found that healthy controls exhibited higher signal detection sensitivity (d') when salient target stimuli were presented on the facial background than when the same stimuli were presented on the grey-oval background. By contrast, patients were not affected by background stimuli when target number stimuli were salient. When target number stimuli were not salient, both patients and controls showed higher d' in the grey-oval background condition compared with the facial background condition. This study highlight the significance of stimulus salience during CPT-IP in schizophrenia as background stimuli did not produce a differential effect on performance. Our results suggest that, in the situations where facial emotion stimuli are present, patients' sustained attention can be deteriorated and that the use of salient materials is important in improving performance in schizophrenia.

Separate and combined effects of low dose ketamine and nicotine on behavioural and neural correlates of sustained attention

Given the cognitive-promoting properties of the nicotinic acetylcholinergic receptor (nAChR) agonist, nicotine, the increased prevalence of smoke-inhaled nicotine in schizophrenia has been interpreted as an attempt to self-correct cognitive deficits, which have been particularly pronounced in the attentional domain. As glutamatergic abnormalities have been implicated in these attentional deficiencies, this study attempted to shed light on the separate and interactive roles of the N-methyl-d-aspartate receptor (NMDAR) and nAChR systems in the modulation of attention by investigating, in healthy volunteers, the separate and combined effects of nicotine and the NMDAR antagonist ketamine on neural and behavioural responses in a sustained attention task. In a randomized, double-blind, placebo controlled study, performance and the P300 event-related brain potential (ERP) in a visual information processing (RVIP) task were examined in 20 smokers and 20 non-smokers (both male and female). Assessment involved intravenous injection of a low subperceptual bolus dose (.04mg/kg) of ketamine or placebo, which was accompanied by acute treatment with nicotine (4mg) or placebo gum. Nicotine-enhanced attentional processing was most evident in nonsmokers, with both performance accuracy and P300 amplitude measures. Ketamine's detrimental effects on these behavioural and electrophysiologic measures were negatively moderated by acute nicotine, the synergistic effects being expressed differently in smokers and nonsmokers. These findings support the view that acute alterations and individual differences in nAChR function can moderate even subtle glutamatergic-driven cognitive deficiencies in schizophrenia and can be important therapeutic targets for treating cognitive impairments in schizophrenia.

Associations of anhedonia and cognition in persons with schizophrenia spectrum disorders, their siblings, and controls

The aim of the current study was to investigate the levels of social and physical anhedonia, as measured with the Chapman Scales for social and physical anhedonia in groups of patients with schizophrenia spectrum psychosis (n = 91), their unaffected siblings (n = 105), and control subjects drawn from a general population (n = 67). The second aim was to explore the effect of physical and social anhedonia on neuropsychological variables. Subjects with schizophrenia spectrum disorder had significantly more anhedonia than population controls, but the unaffected siblings did not differ from controls. Subjects with schizophrenia spectrum disorders had generalized cognitive deficits. Unaffected sibling status predicted impairments in executive and performance speed measures. Elevated physical anhedonia associated with deficits in verbal functions, but this was not related to genetic liability to schizophrenia. In conclusion, social and physical anhedonia did not seem to mediate neuropsychological deficits of schizophrenia family members.

Impaired performance on the Rapid Visual Information Processing task (RVIP) could be an endophenotype of schizophrenia

The aim of the present study was to investigate whether healthy first-degree relatives of schizophrenia patients show reduced sensitivity performance, higher intra-individual variability (IIV) in reaction time (RT), and a steeper decline in sensitivity over time in a sustained attention task. Healthy first-degree relatives of schizophrenia patients (n=23) and healthy control subjects (n=46) without a family history of schizophrenia performed a demanding version of the Rapid Visual Information Processing task (RVIP). RTs, hits, false alarms, and the sensitivity index A' were assessed. The relatives were significantly less sensitive, tended to have higher IIV in RT, but sustained the impaired level of sensitivity over time. Impaired performance on the RVIP is a possible endophenotype for schizophrenia. Higher IIV in RT, apparently caused by impaired context representations, might result in fluctuations in control and lead to more frequent attentional lapses.

'Theory' of mind impairment in patients affected by schizophrenia and in their parents

"Theory of mind" (ToM) is the ability to judge the mental states of the self and others. It is currently considered as a part of the broader concept of social cognition, known to influence the social behaviour of patients affected by schizophrenia. Recently it has been hypothesized that the impairment of ToM is a trait that can be detected both in patients with schizophrenia and in non-psychotic relatives of patients, but it still not clear what the contribution of the familial patterns of cognitive impairment is. The aim of this study is to assess parental impairments of ToM performance considering the effects of the neurocognitive abilities known to be impaired in their first-degree relatives and to influence ToM in schizophrenic patients. Patients, their parents and control trios were assessed with the Wisconsin Card Sorting Test (WCST), the Symbol Coding Task and the ToM Picture Sequencing Task. The ANCOVA analysis on 47 trios including a schizophrenic offspring and 47 healthy trios showed a statistically significant poorer performance of patients and their parents in comparison to control trios at Symbol Coding Task and ToM task. Moreover a regression analysis showed that the neuropsychological abilities tested were significant predictors of ToM performance only in patients. Results confirm a ToM impairment among parents of patients with schizophrenia that is not directly correlated to other aspects of neurocognitive functioning.

Neurodevelopmental factors associated with schizotypal symptoms among adolescents at risk for schizophrenia

Schizophrenia has come to be viewed as a neurodevelopmental disorder that is characterized by genetic vulnerability, stressors during the prenatal period that may be marked by minor physical anomalies and neurobehavioral deficits that emerge in early development. Less is known about the neurodevelopmental origins of schizotypal personality symptoms. The present study examines schizotypal symptoms in Israeli adolescents (mean age = 16.79 years) who have not yet reached the developmental period during which first schizophrenic episode is most likely to emerge: 39 adolescent offspring of parents with schizophrenia, 39 offspring of parents with other psychiatric disorders, and 36 offspring of parents with no history of mental illness. The Semi-Structured Kiddie Interview for Personality Syndromes was used to assess cognitive–perceptual, interpersonal, and disorganized schizotypal symptoms. Interpersonal schizotypal symptoms were more prevalent in the schizophrenia offspring group than in the no-mental-illness offspring group. Among the schizophrenia offspring group, interpersonal, but not cognitive–perceptual, schizotypal symptoms were associated with minor physical anomalies, fine motor dyscoordination, and deficits in executive functioning during adolescence. Among young people whose parents did not have schizophrenia, cognitive–perceptual schizotypal symptoms were correlated with deficits in executive functioning. Adolescent schizotypal symptoms were associated with neurobehavioral symptoms measured during middle childhood in a subgroup of the sample that had been assessed prospectively. Finally, young people who had genetic risk for schizophrenia, minor physical anomalies, and neurobehavioral signs together were at markedly increased risk for symptoms of interpersonal schizotypal symptoms, compared to young people with one or none of these risk factors.

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.

Predictors of remission, schizophrenia, and bipolar disorder in adolescents with brief psychotic disorder or psychotic disorder not otherwise specified considered at very high risk for schizophrenia

OBJECTIVE

The aim of this study was to examine predictors of diagnostic and symptomatic outcome in adolescents with either psychotic disorder not otherwise specified (PsyNOS) or brief psychotic disorder (BrPsy) followed in a schizophrenia prodromal program.

METHODS

As part of a naturalistic study of adolescents considered at clinical high risk for schizophrenia, 26 youths (mean age, 15.9 +/- 2.6 years, 65.4% male) with psychosis not fulfilling criteria for schizophrenia/schizoaffective disorder and diagnosed with PsyNOS or BrPsy were evaluated for predictors of diagnostic and symptomatic outcome after at least 6 (mean, 22.8 +/- 19.4) months follow up.

RESULTS

Progression to schizophrenia, schizoaffective disorder, or psychotic bipolar disorder (n = 10, 38.5%) was predicted by fulfilling criteria for schizotypal personality disorder at baseline (p = 0.046). Development of schizophrenia/schizoaffective disorder (n = 7, 27.0%) was associated with worse executive functioning (p = 0.029) and absence of anxiety disorders (p = 0.027). Conversely, progression to bipolar disorder (n = 4, 15.4%), with (n = 3, 11.5%) or without (n = 1, 3.8%) psychosis, was associated with the presence of anxiety disorders (p = 0.014). Remission of all psychotic as well as attenuated positive or negative symptoms (n = 5, 19.4%) was predicted by Hispanic ethnicity (p = 0.0047), an initial diagnosis of BrPsy (p = 0.014), longer duration of antidepressant treatment (p = 0.035), and better attention at baseline (p = 0.042).

CONCLUSIONS

Results from this preliminary study suggest that patients with PsyNOS, BrPsy, or schizotypal personality disorder features in adolescence should be followed as separate risk groups in prodromal studies of schizophrenia and bipolar disorder. Executive function deficits and absence of anxiety disorders may be risk markers for schizophrenia, while presence of anxiety disorders may be linked to bipolar disorder risk. After achieving full remission, patients with sudden onset of psychosis and brief episodes could once be given the option of careful, supervised treatment discontinuation. The potential salutary effect of antidepressants during the psychotic prodrome and presence of characteristics differentiating patients at risk for schizophrenia or bipolar disorder should be investigated further.

Affective traits in schizophrenia and schizotypy

This article reviews empirical studies of affective traits in individuals with schizophrenia spectrum disorders, population-based investigations of vulnerability to psychosis, and genetic and psychometric high-risk samples. The review focuses on studies that use self-report trait questionnaires to assess Negative Affectivity (NA) and Positive Affectivity (PA), which are conceptualized in contemporary models of personality as broad, temperamentally-based dispositions to experience corresponding emotional states. Individuals with schizophrenia report a pattern of stably elevated NA and low PA throughout the illness course. Among affected individuals, these traits are associated with variability in several clinically important features, including functional outcome, quality of life, and stress reactivity. Furthermore, evidence that elevated NA and low PA (particularly the facet of anhedonia) predict the development of psychosis and are detectable in high-risk samples suggests that these traits play a role in vulnerability to schizophrenia, though they are implicated in other forms of psychopathology as well. Results are discussed in terms of their implications for treatment, etiological models, and future research to advance the study of affective traits in schizophrenia and schizotypy.

Cognitive performance and basic symptoms in first-degree relatives of schizophrenic patients

The aim of the present study was to examine cognitive performance and basic symptoms (BS) in the relatives of schizophrenic patients. The experimental sample comprised 24 first-degree relatives of patients. Each relative was matched to one control. Cognitive tests were: Continuous Performance Test (CPT), N-Back Working Memory Test (N-BACK), Negative Priming Test (NPT), and Span of Apprehension Test (SPAN). The Basic Symptoms Questionnaire (FBF) was used to measure subjective disturbances. The relatives showed only slightly worse cognitive performance than the controls, especially in the tasks with greater cognitive processing load. The relatives also revealed more BS than the controls in the domain of thought, attention, memory, language, and visual representation. Only CPT performance was hardly associated with BS. The negative correlation between FBF and CPT was strongly evident in the relatives with poorer processing capacity. This finding suggests that the BS are associated with sustained attention performance. Future research is needed to clarify whether BS are related to other cognitive domains.

Inverted-U dopamine D1 receptor actions on prefrontal neurons engaged in working memory

Dopamine (DA) D1 receptor (D1R) stimulation in prefrontal cortex (PFC) produces an 'inverted-U' dose-response, whereby either too little or too much D1R stimulation impairs spatial working memory. This response has been observed across species, including genetic linkages with human cognitive abilities, PFC activation states and DA synthesis. The cellular basis for the inverted U has long been sought, with in vitro intracellular recordings supporting a variety of potential mechanisms. The current study demonstrates that the D1R agonist inverted-U response can be observed in PFC neurons of behaving monkeys: low levels of D1R stimulation enhance spatial tuning by suppressing responses to nonpreferred directions, whereas high levels reduce delay-related firing for all directions, eroding tuning. These sculpting actions of D1R stimulation are mediated in monkeys and rats by cyclic AMP intracellular signaling. The evidence for an inverted U at the cellular level in behaving animals promises to bridge in vitro molecular analyses with human cognitive experience.

The Consortium on the Genetics of Schizophrenia: neurocognitive endophenotypes

The Consortium on the Genetics of Schizophrenia (COGS) is a 7-site collaboration that examines the genetic architecture of quantitative endophenotypes in families with schizophrenia. Here we review the background and rationale for selecting neurocognitive tasks as endophenotypic measures in genetic studies. Criteria are outlined for the potential of measures as endophenotypic vulnerability markers. These include association with illness, state independence (ie, adequate test-retest stability, adequate between-site reliability, impairments in patients not due to medications, impairments observed regardless of illness state), heritability, findings of higher rates in relatives of probands than in the general population, and cosegregation within families. The COGS required that, in addition, the measures be "neurocognitive" and thus linked to neurobiology and that they be feasible in multisite studies. The COGS neurocognitive assessment includes measures of attention, verbal memory, working memory, and a computerized neurocognitive battery that also includes facial processing tasks. Here we describe data demonstrating that these neurobehavioral measures meet criteria for endophenotypic candidacy. We conclude that quantitative neurocognitive endophenotypes need further evidence for efficacy in identifying genetic effects but have the potential of providing unprecedented insight into gene-environment interaction related to dimensions of brain and behavior in health and disease.

Generalized and specific cognitive performance in clinical high-risk cohorts: a review highlighting potential vulnerability markers for psychosis

Cognitive deficits are a core feature of established psychotic illnesses. However, the association between cognition and emerging psychosis is less understood. While there is some evidence that cognitive deficits are present prior to the onset of psychosis, findings are not consistent. In this article we provide an overview of the more general cognitive findings available from genetic high-risk studies, retrospective studies, and birth cohort studies. We then focus the review on neuropsychological performance in clinically "at-risk" groups. Overall, general cognitive ability as assessed by established batteries appears to remain relatively intact in these ultra-high risk cohorts and is a poor predictor close to illness onset relative to other vulnerability factors. Further decline may occur with illness progression, more consistent with state relative to trait factors. In addition, most established cognitive tasks involve several relatively discrete cognitive subprocesses, where findings from general batteries of subtests may mask specific deficits. In this context, our review suggests that relatively specific olfactory identification and spatial working memory deficits exist prior to illness onset and may be more potent trait markers for psychosis than cognitively dense tasks such as verbal memory. Suggestions for further research address the importance of standardization of inclusion criteria and the maintenance of basic neuropsychological assessment to allow better comparison of findings across centers. Further, in order to better understand the aetiopathology of cognitive dysfunction in psychosis, more experimental, hypothesis-driven measures of discrete cognitive processes are required. Delineation of the relationship between specific cognitive ability and symptoms from data-driven approaches may improve our understanding of the role of cognition during psychosis onset.

Neuropsychological functioning in adolescents and young adults at genetic risk for schizophrenia and affective psychoses: results from the Harvard and Hillside Adolescent High Risk Studies

Siblings and offspring of persons with schizophrenia carry elevated genetic risk for the illness and manifest attentional and memory impairments. Because less is known about other neuropsychological functions and their specificity in adolescents, we conducted a genetic high-risk (HR) study of schizophrenia (HR-SCZ) and affective psychosis (HR-AFF). Participants (ages 12-25) were from the Harvard Adolescent High-Risk and Hillside Family studies, including 73 HR-SCZ, 18 HR-AFF, and 84 community controls (CCs) recruited in metropolitan Boston and New York. Groups were compared on overall neurocognitive functioning, 6 domains, and 13 test scores, controlling for age, parental education, and correlated data within families. The HR-SCZ group was significantly impaired overall, while the HR-AFF group demonstrated a trend toward overall impairment. HR-SCZ subjects showed significantly lower Verbal Ability (d = .73) and Executive Functioning/Working Memory (d = .47) than CCs. HR-AFF subjects showed reduced Verbal Ability (d = .64) compared to CCs. Excluding 12 CCs with a parental history of depression (without psychosis) led to larger differences between HR and CC groups across domains. Moreover, HR-SCZ and CC group differences in Verbal Memory (d = .39) and Visual-Spatial (d = .34) became statistically significant. There were no significant differences between HR-SCZ and HR-AFF groups. Data support a modest neuropsychological deficit in persons at genetic HR for psychosis, with a broader range of deficits in HR-SCZ. Future work should assess the relationship of neurocognition to adaptive functioning and possible onset of psychosis in HR samples. Ascertainment criteria for controls may markedly influence results and interpretation of group differences.

A review of emotion deficits in schizophrenia

Emotion deficits in schizophrenia have been described since the time of Kraepelin. However, no comprehensive review of clinical emotion studies has ever been conducted, in this work, studies that used diagnostic criteria and were published in English were selected from an extensive PubMed search. Fifty-five studies on emotion expression repeatedly showed that individuals with schizophrenia (IWSs) display fewer overt expressions than non patient comparison subjects (NCSs) in verbal, facial, and acoustic channels. No clear differences were found between IWSs and depressed subjects. Sixty-nine studies examined emotion experience in schizophrenia. IWSs report higher anhedonia, and they tend to show more negative emotions in real-life event studies. In evocative studies, they report a similar degree of pleasantness and a similar or higher degree of unpleasantness. From 110 studies, ii can be concluded that emotion recognition is impaired in schizophrenia in all channels. These deficits in social perception are correlated with neurocognitive deficits and some social skills. IWSs show dysfunction in the three domains of emotion expression, emotion experience, and emotion recognition, and these dysfunctions appear to be independent of each other across domains. These deficits in basic emotion processing may be linked to psychopathology and functional outcomes.

Anhedonia in schizophrenia: a review of assessment strategies

Anhedonia, the diminished capacity to experience pleasant emotions, is a common, treatment-resistant feature of schizophrenia that is often included among the negative symptoms of this disorder. This selective review describes the 3 most commonly used approaches to assess anhedonia in schizophrenia: interview-based measures, self-report trait questionnaires, and laboratory-based assessments of emotional experience. For each assessment approach, psychometric properties, relationships to other symptoms and features of schizophrenia, and relationships with the other assessment approaches are evaluated. It is concluded that anhedonia can be reliably assessed and constitutes a distinctive, clinically important aspect of schizophrenia that should be included in a comprehensive evaluation of negative symptoms. Current efforts to define more precisely the nature of the hedonic deficit in schizophrenia are discussed, and recommendations for optimal assessment of anhedonia in clinical trials of novel treatments for negative symptoms are provided.

Sustained attention deficits in relation to psychometrically identified schizotypy: evaluating a potential endophenotypic marker

Sustained attention deficits have been posited as a potential endophenotypic marker of vulnerability to schizophrenia. Prior studies have indicated that schizophrenia patients, their first-degree relatives, and psychosis-prone individuals, identified on the basis of measures of positive schizotypy, have demonstrated sustained attention deficits. To date, there have been no published reports of sustained attention deficits in individuals with negative schizotypy, as measured by the revised Social Anhedonia Scale. In this study, we examined sustained attention, measured with the CPT-Identical Pairs version, in 160 individuals with elevated scores on the Chapman Perceptual Aberration and/or Magical Ideation Scales, 96 individuals with elevated scales on the Social Anhedonia Scale, and 137 controls. Both psychosis-prone groups performed more poorly than the controls in terms of discrimination ability, as measured by d', though the groups did not differ in terms of either their reaction time or overall response criterion (lnbeta). These results provide evidence that both positive and negative aspects of schizotypy are associated with sustained attention deficits, as measured by the Continuous Performance Test. The findings add to the converging evidence indicating that sustained attention deficits are a potential endophenotypic indicator of a schizophrenia diathesis.

The use of neurophysiological endophenotypes to understand the genetic basis of schizophrenia

Specifying the complex genetic architecture of the “fuzzy” clinical phenotype of schizophrenia is an imposing problem. Utilizing metabolic, neurocognitive, and neurophysiological “intermediate” endophenotypic measures offers significant advantages from a statistical genetics stand-point. Endophenotypic measures are amenable to quantitative genetic analyses, conferring upon them a major methodological advantage compared with largely qualitative diagnoses using the Diagnostic and Statistical Manual of Mental Health, 4th Edition (DSM-IV). Endophenotypic deficits occur across the schizophrenia spectrum in schizophrenia patients, schizotypal patients, and clinically unaffected relatives of schizophrenia patients, Neurophysiological measures, such as P50 event-related suppression and the prepulse inhibition (PPI) of the startle response, are endophenotypes that can be conceptualized as being impaired because of a single genetic abnormality in the functional cascade of DNA to RNA to protein. The “endophenotype approach” is also being used to understand other medical disorders, such as colon cancer, hemochromatosis, and hypertension, where there is interplay between genetically conferred vulnerability and nongenetic stressors. The power and utility of utilizing endophenotypes to understand the genetics of schizophrenia is discussed in detail in this article.

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.

Personality differences in schizophrenia are related to performance on neuropsychological tasks

Altered cognition and personality appear to emerge in tandem and adversely affect outcome in schizophrenia, yet little research has been done to determine whether these are related or independent domains. In this study, the relationship between the Big Five personality traits--neuroticism, extraversion, openness, agreeableness, conscientiousness--and cognitive and motor performance in outpatients with chronic, clinically stable schizophrenia (N = 30) and age-matched healthy comparison subjects (N = 45) was examined. Subjects completed tests of attention, executive and motor functions, and the NEO-Five Factor Personality Inventory. Patients scored significantly higher on neuroticism and lower on extraversion and agreeableness, but after variance due to neuropsychological performance was statistically removed from NEO scale scores, personality dimensions and profiles no longer differed between groups. Neuropsychological performance and demographic variables, but not diagnosis, uniquely accounted for statistically significant amounts of personality variance, and neuropsychological task performance was correlated with personality dimensions in both patients and comparison subjects. These cross-sectional data provide preliminary evidence that personality dysfunction in schizophrenia may be mediated by disease-related changes in cognitive operations, or the neural processes underlying them. Longitudinal studies utilizing more comprehensive measures of neurocognitive performance are needed to define further the relationship between neuropsychological function and personality in schizophrenia.

Does contextual information influence positive and negative schizotypy scores in healthy individuals? The answer is maybe

Defensive responding in schizotypy questionnaires might depend on context. Students completed a schizotypy questionnaire in a "psychiatric" context or a "creativity" context. Positive, but not negative, schizotypy scores were lower in the psychiatry than in the creativity group, but findings applied mainly to male participants. The implications of these findings are critically discussed.

Cognitive functioning in siblings discordant for schizophrenia

OBJECTIVE

The objective of this study was to investigate neuropsychological impairment as a genetically mediated risk indicator for schizophrenia while accounting for prevalence of schizotypy signs/symptoms in siblings.

METHOD

Cognitive functioning in 25 individuals with schizophrenia, 25 unaffected siblings and 25 unrelated healthy controls, was assessed using neuropsychological tests of sustained attention, memory and learning, executive function, visual-spatial ability and psychomotor performance.

RESULTS

Unaffected siblings demonstrated better performance than patients on some measures of memory and learning and executive function. Patients and siblings demonstrated impaired Full Scale IQ and verbal fluency, otherwise siblings performed similarly to healthy controls. Controlling for differences in IQ, the shared deficit in verbal fluency disappeared.

CONCLUSION

Patients with schizophrenia and unaffected siblings (without schizotypy personality disorder) shared a neuropsychological deficit in verbal fluency. This deficit appeared to be mediated by IQ. Deficits, which differentiated patients from controls, may not be inherited and perhaps are related to the manifestation or treatment of schizophrenia.

Working memory functioning in schizophrenia patients and their first-degree relatives: cognitive functioning shedding light on etiology

There is accumulating evidence for involvement of the prefrontal cortex (PFC) in the pathophysiology of schizophrenia. A primary function supported by the PFC is working memory (WM). Findings from WM studies in schizophrenia can provide insight into the nature of clinical symptoms and cognitive deficits associated with this disorder, as well as begin to suggest areas of underlying neuropathology. To date, studies have not adequately investigated different WM domains (e.g., verbal, spatial, or object) or processing requirements (e.g., maintenance, monitoring, or manipulation), shown to be associated with distinct patterns of neural activation, in schizophrenia patients and their well relatives. Accordingly, this study evaluated the performance of schizophrenia patients, their first-degree biological relatives, and nonpsychiatric controls on a comprehensive battery of WM tasks and investigated the association among WM deficits and schizophrenia-spectrum psychopathology. The findings indicate that schizophrenia patients are consistently impaired on WM tasks, irrespective of WM domain or processing requirements. In contrast, their unaffected relatives are only impaired on WM tasks with higher central executive processing requirements. This pattern of WM performance may further implicate DLPFC dysfunction in the liability for schizophrenia and has implications for future cognitive, genetic, and neurodevelopmental research.

Are there attentional deficits in people putatively at risk for affective disorders?

BACKGROUND

Schizophrenia is associated with attentional dysfunctions. In bipolar disorder, there is also evidence for sustained attention deficits. Therefore, we hypothesized that risk for bipolar disorder but not for unipolar depression might be associated with attentional abnormalities as well.

METHOD

Using the Hypomanic Personality Scale (HPS) and the Rigidity Scale, we defined three groups: bipolar at-risk (n=42), unipolar at-risk (n=34), and control (n=37). All completed the d2 Test and the Continuous Performance Test (CPT).

RESULTS

There was no evidence for overall attentional deficits in people at risk for affective disorders. However, reduced sensitivity, i.e., less discrimination between targets and nontargets, was observed in people at risk for bipolar disorders who also displayed schizotypy.

LIMITATIONS

We only looked at selective and sustained attention and did not assess other factors such as memory or executive functions. Additionally, the risk status was only defined by a psychometric indicator and did not include other approaches of defining risk (e.g., first-degree relatives).

CONCLUSIONS

Despite some limitations, our results support on one hand the idea that vulnerability for bipolar disorder can be associated with cognitive impairments, but they also highlight that this is not generally the case. Vulnerability for bipolar disorder and schizotypy might be correlated but are not the same.

Cognitive deficits in relatives of patients with schizophrenia: a meta-analysis

BACKGROUND

Schizophrenia is characterized by a generalized cognitive impairment with pronounced deficits in the domains of verbal memory, executive functioning and attention.

AIM

To investigate whether cognitive deficits found in patients with schizophrenia are also found in non-affected relatives.

METHOD

A meta-analytic review of the published literature on cognitive performance between relatives of schizophrenic patients and healthy controls.

RESULTS

The meta-analyses yielded nine weighted effect sizes from 37 studies comprising 1639 relatives of schizophrenia patients and 1380 control subjects. The largest differences were found on verbal memory recall (d=0.54, 95% CI=0.43-0.66) and executive functioning (d=0.51, 0.36-0.67). Attentional functioning showed smaller effect sizes (d=0.28, 0.06-0.50). These effect sizes are in the moderate range.

CONCLUSION

Cognitive deficits found in patients with schizophrenia are also found in non-affected relatives. This finding is consistent with the idea that certain cognitive deficiencies in relatives are caused by familial predisposition to schizophrenia and that these deficiencies might be putative endophenotypes for schizophrenia. However, our results do not address genetic causes directly. Further work is needed to determine whether certain cognitive traits are familial and whether there is co-inheritance of these traits with schizophrenia within families.

Cognitive dysfunctions in parents of schizophrenic patients parallel the deficits found in patients

Schizophrenia is characterized by a global cognitive impairment, with varying degrees of deficit in all ability domains. Since genetic factors are important in the etiology of schizophrenia we investigated whether parents of schizophrenic patients also show cognitive deficits, particularly on those cognitive ability domains that are most severely affected in patients. Both biological parents of 37 patients with schizophrenia (N=74 subjects) and 28 comparable healthy married control couples (N=56 subjects) were included. A comprehensive and standardized cognitive battery was used including tests measuring verbal memory, executive functioning, language, attention, and psychomotor functioning. Parents of patients differed from control couples on those cognitive constructs that are generally considered to be most impaired in schizophrenic patients, i.e. global verbal memory, bilateral motor skill, continuous performance, and word fluency. In addition, parents differed significantly from control couples on some other cognitive constructs on which patients show a smaller but also significant difference compared to healthy controls, i.e. unilateral motor skill and digit span. Results suggest that the cognitive constructs on which patients show relatively most severe impairment may prove suitable as endophenotypic markers in schizophrenia.

Sustained attention impairment correlates to gray matter decreases in first episode neuroleptic-naive schizophrenic patients

Impaired sustained attention seems to be a specific neuropsychological deficit that is closely linked to schizophrenia. Voxel based morphometry has emerged as a useful tool for the detection of subtle gray matter (GM) abnormalities. The aim of our study was to identify the cerebral regions related to the Identical-Pair version of the Continuous Performance Test (CPT-IP) performance in schizophrenic patients. The study included 13 right-handed, male, first-episode, paranoic, neuroleptic-naive schizophrenic patients and 13 matched controls. High-resolution whole-brain MR images were segmented and analyzed for the whole brain and for regions of interest (ROI) using SPM99. Furthermore, the correlation between CPT-IP performance and GM density was examined. Volumetric analysis of the thalami was also carried out. GM density analysis shown decreases in patients in anterior cingulate gyrus, left inferior frontal, right claustrum, left pulvinar, and dorsomedial bilateral thalamic nuclei, and caudate nuclei as well as left hippocampus and parahippocampal gyrus. Thalamic ROIs revealed a strong correlation between groups differences. The thalamic GM density allowed a good individual classification. GM increases were detected in left insula, superior temporal gyrus, and putamen nucleus, and right supramarginal gyrus. Schizophrenic patients showed smaller left and right thalamic volumes. We found that GM density of the left thalamic nucleus, left angular, and supramarginal gyrus, and left inferior frontal and postcentral gyri correlated significantly with CPT-IP performance in patients but not in controls. Moreover, the restricted ROIs regression was strongly significant for both left and right thalamus. In summary, we provide evidence for the involvement of thalamic, inferior-parietal, and frontal regions in the attentional deficits observed in schizophrenic patients.

Anhedonia in schizophrenia: a distinct familial subtype?

Failures to replicate results in psychiatric genetics might be due to our inability to define the heritable phenotype. Instead of relying entirely on classical nosographical approaches, the use of a candidate symptom approach to identify more homogeneous forms of diseases among affected subjects and subclinical traits among first-degree relatives may increase genetic validity. Anhedonia may be a marker for subjects at risk of schizophrenia or schizophrenia spectrum disorders. We compared the familiality of anhedonia characterized by a high level of physical anhedonia (score above 23) in a sample of schizophrenic probands (N=80) and their relatives (N=78), with that in bipolar patients (N=109), their relatives (N=33) and normal controls (N=94). We identified a subform of schizophrenia characterized by highly anhedonic schizophrenic probands with a three-fold higher familial risk of schizophrenia and schizophrenic spectrum disorders. We also found that their first-degree relatives had a high level of anhedonia. An intrafamilial correlation analysis confirmed the familial nature of anhedonia. Our data suggest that anhedonia is a candidate symptom for schizophrenia. Refining phenotype definition by studying subgroups of anhedonic and non-anhedonic probands with relevant candidate genes might be fruitful.

Psychosis proneness and ADHD in young relatives of schizophrenia patients

Symptoms resembling the attentional deficit hyperactivity disorder (ADHD) are frequently observed in young relatives at risk for schizophrenia (HR). We examined the frequency of the ADHD syndrome and its relationship to psychosis related psychopathology and neurobehavioral abnormalities in young HR subjects (n=29) and healthy comparison subjects (HC; n=30). Thirty-one percent of HR subjects (n=9) had ADHD as a lifetime Axis-I diagnosis (HR-A). Compared to healthy comparison subjects, the HR-A group had impaired neurological function. The HR-A group but not the HR subjects without ADHD had higher scores on the Chapman's magical ideation and perceptual aberration scales. Thus, ADHD-like features are more prevalent in the HR population than the one described in the general population and are associated with more frequent psychosis-like clinical features. Longitudinal studies can clarify whether an "ADHD subgroup" within HR subjects predict an increased risk for future emergence of schizophrenia.

Executive/attentional cognitive functions in schizophrenic patients and their parents: a preliminary study

The aim of this study was to determine whether executive/attentional cognitive performances could be considered as markers of vulnerability to schizophrenia. The Stroop Color Word and fluency tests were significantly impaired in schizophrenic patients and their parents compared to controls matched on age and sex while performances on Nelson's Modified Card Sorting Test and the Trail Making Test did not differ. The impairments on the Stroop and fluency could be considered as endophenotypic markers of schizophrenia.

Implicit memory in schizotypal subjects and normal controls: effects of a secondary task on sequence learning

Using a serial reaction-time task, the implicit memory performances of 29 high scoring (schizotypes) and 24 low scoring subjects (controls) on the German version of the 1997 Schizotypal Personality Questionnaire by Klein, Andresen, and Jahn were compared. To test the hypothesis that schizotypes show a differential deficit, subjects participated either in a single task condition of the serial reaction-time task or in a dual task condition of a secondary tone-counting task. Neither under single task conditions nor under dual task conditions did schizotypes show any impairment of implicit memory compared with controls. In addition, a separate analysis of the response latencies for the unique and ambiguous transitions of the repeated sequence did not indicate any differences between the two groups. These findings support and augment the results reported by Ferraro and Okerlund (1995).

Hypomanic personality, social anhedonia and impulsive nonconformity: evidence for familial aggregation?

Schizophrenic and affective spectrum disorders aggregate in the families of patients afflicted with such disorders. Possible vulnerability markers for these disorders should therefore also run in families. The Chapmans and their coworkers developed the Hypomanic Personality Scale (HYP) to identify people at risk for affective disorders, and the scales Social Anhedonia (SA) and Impulsive Nonconformity (IMP) to assess schizotypy (Chapman et al., 1976, 1984; Eckblad & Chapman, 1986). The present family study investigated the familial resemblance of the HYP, SA, and IMP Scale using a maximum-likelihood approach. Index participants and their relatives (n = 717) completed a questionnaire packet that included the above-mentioned scales. Stepwise several models of familial correlations were specified and tested dealing with the influence of sex of parents and offspring and of interindividual cross-trait resemblance. For all three measures, there was evidence of familial resemblance. For SA and IMP, we found hints for possible assortative mating; additionally for HYP and IMP, an interindividual cross-trait resemblance (with correlations of 0.14 and 0.18, respectively) between family members emerged. The results support the validity of the HYP, SA, and IMP Scale. It is discussed whether HYP and IMP represent different aspects of a shared latent liability.

Continuous performance tests are sensitive to ADHD in adults but lack specificity. A review and critique for differential diagnosis

Historically, the focus for Attention Deficit Hyperactivity Disorder (ADHD) has been on children, with considerable research and many opinions available in this area. More recently, the focus has been expanded to include ADHD in adults. Assessment of ADHD in adults is complicated by the high rate of co-occurring disorders as well as symptom overlap with a number of disorders. One popular family of measures for the assessment of attention and executive control is the continuous performance test (CPT). A review of the available research on CPTs reveals that they are quite sensitive to CNS dysfunction. This is both a strength and a limitation of CPTs in that multiple disorders can result in impaired performance on a CPT. The high sensitivity of CPTs is further complicated by the multiple variations of CPTs available, some of which may be more sensitive or demonstrate better specificity to ADHD in adults than others. If CPTs are to be used clinically, further research will be needed to answer the questions raised by this review.

Stress affects the selection of relevant from irrelevant stimuli

Two experiments were used to examine the effects of stress on latent inhibition (LI; poorer learning with a previously exposed irrelevant stimulus rather than a novel stimulus). In Experiment 1, stress was induced in college students by threatening participants' self-esteem with a difficult number series completion test that was related to intelligence. In Experiment 2, the participants were job seekers who were either informed or not that the LI test was part of the selection process. In both experiments, LI was attenuated in high- as compared with low-stressed participants. The results suggest that stress and/or anxiety impairs the inhibition of irrelevant-preexposed stimuli. Implications for understanding the impaired selective attentional processes in schizophrenia and schizotypy are discussed.