Cognitive brain potentials in children at risk for schizophrenia: preliminary findings

An opportunity for primary prevention research in psychotic disorders

An opportunity has opened for research into primary prevention of psychotic disorders, based on progress in endophenotypes, genetics, and genomics. Primary prevention requires reliable prediction of susceptibility before any symptoms are present. We studied a battery of measures where published data supports abnormalities of these measurements prior to appearance of initial psychosis symptoms. These neurobiological and behavioral measurements included cognition, eye movement tracking, Event Related Potentials, and polygenic risk scores. They generated an acceptably precise separation of healthy controls from outpatients with a psychotic disorder. METHODS: The Bipolar and Schizophrenia Network on Intermediate Phenotypes (B-SNIP) measured this battery in an ancestry-diverse series of consecutively recruited adult outpatients with a psychotic disorder and healthy controls. Participants include all genders, 16 to 50 years of age, 261 with psychotic disorders (Schizophrenia (SZ) 109, Bipolar with psychosis (BPP) 92, Schizoaffective disorder (SAD) 60), 110 healthy controls. Logistic Regression, and an extension of the Linear Mixed Model to include analysis of pairwise interactions between measures (Environmental kernel Relationship Matrices (ERM)) with multiple iterations, were performed to predict case-control status. Each regression analysis was validated with four-fold cross-validation. RESULTS AND CONCLUSIONS: Sensitivity, specificity, and Area Under the Curve of Receiver Operating Characteristic of 85%, 62%, and 86%, respectively, were obtained for both analytic methods. These prediction metrics demonstrate a promising diagnostic distinction based on premorbid risk variables. There were also statistically significant pairwise interactions between measures in the ERM model. The strong prediction metrics of both types of analytic model provide proof-of-principle for biologically-based laboratory tests as a first step toward primary prevention studies. Prospective studies of adolescents at elevated risk, vs. healthy adolescent controls, would be a next step toward development of primary prevention strategies.

P300 amplitude attenuation in high risk and early onset psychosis youth

Little research has investigated the use of electrophysiological biomarkers in childhood and adolescence to distinguish early onset psychosis and the clinical high risk state. The P300 evoked potential is a robust neurophysiological marker of schizophrenia that is dampened in patients with schizophrenia and, less consistently, in those with affective psychoses and those at clinical high risk for psychosis (CHR). How it may differ between patients with psychotic disorders (PS) and CHR is less studied, especially in youth. The current study compared P300 activity among children and adolescents, aged 5-18 years, at CHR (n = 43), with PS (n = 28), and healthy controls (HC; n = 24). Participants engaged in an auditory event-related potential (ERP) task to elicit a P300 response and completed clinical interviews to verify symptoms and diagnoses. Linear regression analyses revealed a decrease in P300 amplitude with increased severity of psychotic symptoms. PS participants showed a diminished P300 response compared to those at CHR and HC, particularly among adolescents aged 13-18. This response was most evident at centroparietal and parietal locations in the right hemisphere. The findings suggest that high risk and psychotic symptomatology is linked to attenuated parietal P300 activity in youth as young as 13 years. Further exploration of the P300 as a biomarker for psychosis in very young patients could inform tailored, appropriate interventions at early stages of disease progression. Future research should evaluate whether specific phenotypic and genotypic characteristics are differentially associated with neurophysiological biomarkers and whether P300 attenuation in CHR youth can predict later symptom severity.

Executive dysfunction in Turkish children at high risk for schizophrenia

OBJECTIVE

To explore different aspects of executive function (i.e. sequencing, set shifting and mental flexibility) in children who are at high risk for schizophrenia by comparing them with normal controls.

METHOD

The high risk (HR) group consisted of 30 children whose parents were diagnosed as schizophrenia. As the control group (CG) 30 children, whose parents did not meet any DSM IV diagnostic criteria for any psychiatric disorder, participated. They were age and sex matched with the HR group. For the evaluation of different domains of cognitive functions Wechsler intelligence scale for children-revised (WISC-R), and a group of neuropsychological tests, including Trail Making A-B Tests, Color Form Test, and Progressive Figures Test were administered. Behavioral problems were assessed using Hacettepe Adjustment Scale.

RESULTS

The subjects in the high risk group had significantly lower scores on Trail Making A-B, Color Form, Progressive Figures Tests, as well as subtests and scores of WISC-R (Information, Comprehension, Similarities, Picture Completion, Block Design, Object Assembly and Coding subtests, Verbal, Performance and Full Scale IQ scores). There is no significant difference between the two groups in the frequency and severity of behavioral problems.

CONCLUSION

Children of parents with schizophrenia displayed significantly greater number of difficulties in several areas of executive function, such as sequencing, set shifting, and mental flexibility, when compared to their controls.

Preattentional and attentional cognitive deficits as targets for treating schizophrenia

BACKGROUND AND RATIONALE

Pharmacotherapy of schizophrenia has traditionally targeted positive psychotic symptoms. An emerging view is that developing medications that improve cognition in schizophrenia patients is a major step forward in achieving better functional outcome. The cognitive deficits that are often observed in schizophrenia can be assessed using (1) neuropsychological tests; and (2) neurophysiological tests, the topic of this article. These neurophysiological measures cover a spectrum from automatic preattentional to attention-dependent processes.

OBJECTIVES

This article focuses on cognitive deficits that appear to be promising targets for a new "third generation" of medications that may be used to treat schizophrenia and other patients with specific deficits in cognition and functioning. We discuss the possible use of the following six measures of preattentional and attention-dependent cognitive deficits: mismatch negativity, P50 event-related potential suppression, prepulse inhibition of the startle response, P300 event-related potential, continuous performance task performance, and oculomotor antisaccade performance.

CONCLUSIONS

The use of preattentional and attention-dependent measures offer unique opportunities to improve our armamentarium of pharmacologic strategies for the treatment of cognitive deficits in schizophrenia patients. This review illustrates the usefulness of these measures as targets for existing and new antipsychotic medications that will potentially (1) characterize the cognitive deficits that occur in schizophrenia patients and (2) assess medication-related improvement on these measures and the potential associated improvement in functional outcome.

Neurophysiologic correlates of psychiatric disorders and potential applications in epilepsy

There is increasing interest in psychiatric assessment using neurophysiologic tools such as electroencephalography (EEG), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). This is because these technologies have good temporal resolution, are relatively noninvasive, and (with the exception of MEG) are economical. Many different experimental paradigms and analysis techniques for the assessment of psychiatric patients involving these technologies are reviewed including conventional quantitative electroencephalography (QEEG), EEG cordance, low-resolution electromagnetic tomography (LORETA), frontal midline theta, midlatency auditory evoked potentials (P50, N100, P300), loudness dependency of the auditory evoked potential (LDAEP), mismatch negativity (MMN), contingent negative variation (CNV), and transcranial magnetic stimulation (TMS). Many of these neurophysiologic stimulus paradigms hold the promise of improving psychiatric patient care by improving diagnostic precision, predicting treatment response, and providing new phenotypes for genetic studies. Large cooperative multisite studies need to be designed to test and validate a few of these paradigms so that they might find use in routine clinical practice.

[The p300 cognitive event-related potential. II. Individual variability and clinical application in psychopathology]

The P300 wave is one of the cognitive components of the event-related potential (ERP) that is used to investigate the cognitive processes, and which can be used to study patient populations with a variety of psychiatric disorders. Its clinical utility has been increased by the identification of factors that contribute to the variability in its amplitude and latency. However, its value as a diagnostic index has not been entirely established. It can provide a useful recording of patients' information processing, and indicate the severity of the clinical state and its possible evolution. It can also assist in determining what therapeutic approach to adopt. In the present review, the findings in the literature concerning interindividual variation in the P300 wave are first described; several variables significantly influence the amplitude and latency of this wave, such as age, gender, intelligence and personality. Following this, the relevance of the data in the literature on the clinical applications of P300 in psychopathology is examined, including the studies undertaken to obtain an objective diagnostic index for mental disorders and also those carried out to assess the problems concerning the interpretation of information connected with the mental pathologies examined. P300-associated findings on dementia, schizophrenia, depression, alcoholism, drug addiction, anxiety disorders (panic disorder, obsessive-compulsive disorder, and post-traumatic stress syndrome) and on personality disorders (schizoid, antisocial or borderline personality disorder) have been examined in detail.

Event-related potentials and thought disorder in schizophrenia

We examined the relationship between event-related potentials and thought disorder in schizophrenia. The subjects were 29 chronic schizophrenic patients. Thought disorder was assessed using the Comprehensive Index of Positive Thought Disorder developed by Harrow and colleagues (Harrow and Quinlan, 1985; Marengo et al., 1986). Auditory event-related potentials were recorded during a standard oddball task. The P300 amplitude correlated negatively with the severity of the thought disorder. The P300 amplitude in the patients with thought disorder was significantly smaller than in the patients without thought disorder. These results suggest that a reduction in P300 amplitude is associated with a fundamental impairment of information processing in schizophrenic patients.

Basic symptoms and P300 abnormalities in young schizophrenic patients

Among the reasons for the relatively limited number of investigations of self-knowledge phenomena should be included, in addition to theoretical motives, the difficulties regarding the use of instruments available for this kind of approach and their content validity. This study investigates the relationship between subjective and objective deficits in schizophrenia, taking into account subjective experiences of cognitive impairment, clinical symptoms, and cognitive evoked potentials (P300 component). A group of 36 young schizophrenic patients (29 on neuroleptic treatment and seven drug-naive) were considered, together with a comparison group of 36 healthy subjects. Auditory event-correlated potentials (ERPs) were obtained using a simple "oddball" paradigm. Clinical symptoms were rated with the Brief Psychiatric Rating Scale (BPRS) and Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS), and while subjective disturbances were assessed by the Frankfurter Beschwerde Fragebogen (FBF, also called the Complaint Questionnaire). Correlation analysis showed that P300 amplitude was inversely correlated with subjective experiences of cognitive deficit, especially in the area of automatic skills and overstimulation. No relationship emerged between BPRS, SANS, and SAPS scores and P300 alterations. The results suggest that subjective cognitive disturbances, more than objective symptoms, are related to P300 alterations in schizophrenia, and that the FBF questionnaire appropriately covers the domain of schizophrenic cognitive disorders.

P300 decrements in teenagers with conduct problems: implications for substance abuse risk and brain development

BACKGROUND

The purpose of this study was to evaluate the effects of conduct disorder problems, family history, gender, and age on P300 electroencephalographic potentials in teenagers.

METHODS

The 257 subjects, aged 15 to 20 years, were assigned to one of twelve groups defined by the crossing of three between-subjects factors: 1) gender; 2) ranking below vs above the median number of conduct disorder problems for their gender; and 3) no family history of alcohol or drug dependence vs familial alcohol dependence vs familial heroin or cocaine dependence.

RESULTS

P300 amplitude was smaller among subjects reporting a greater number of conduct problems prior to age 15 vs those reporting fewer problems of this type. No family history effects were detected. Another set of analyses examined the effects of age on conduct problem-related decrements in P300. Smaller P300 amplitudes within the posterior scalp region were associated with a greater number of conduct problems among subjects younger than 16.5 years. Among subjects greater than this median age, the effects of these behaviors were only apparent over the frontal scalp.

CONCLUSIONS

It is concluded that P300 decrements previously attributed to familial alcohol/substance dependence might be the result of a coincident increase in the prevalence of conduct disorder problems. The analysis of age interactions suggests that P300 amplitude decrements observed at posterior scalp sites among subjects with more conduct problems disappear at approximately 16 to 17 years of age. After that age, decrements in frontal brain function may begin to emerge in the subset of conduct problem subjects who are at risk for developing adult antisocial personality disorder.

Auditory event-related potentials to tone stimuli in combat-related posttraumatic stress disorder

This study attempted to replicate findings of abnormal auditory event-related potentials (ERPs) in posttraumatic stress disorder (PTSD) in a sample of Vietnam combat veterans. Veterans with combat-related PTSD, divided into unmedicated (unmed-PTSD, n = 12) and medicated (med-PTSD, n = 22) groups, and veterans without PTSD (non-PTSD, n = 10) completed a three-tone "oddball" target detection task while ERPs were measured. Individuals with comorbid panic disorder (PD) were excluded from the primary analyses. Parietal P3 amplitude to the target tone was significantly smaller in unmed-PTSD compared to med-PTSD and non-PTSD groups. These differences did not remain significant when an adjustment was made for level of depression. Parietal P3 amplitude was also negatively correlated with state anxiety. Secondary analyses within the unmed-PTSD group indicated that participants with comorbid PD (n = 3) had the largest parietal P3 amplitudes to target tones. Results are consistent with attentional or concentration deficits in PTSD and highlight the importance of considering comorbid diagnoses. The absence of ERP differences between med-PTSD and non-PTSD participants suggests that psychotropic medication may normalize these deficits.

Deviate P200 and P300 in non-patient college students with high scores on the schizophrenia scale of the Minnesota Multiphasic Personality Inventory (MMPI)

Event-related potentials (ERPs) were examined in 16 college students who had high scores on the Schizophrenia Scale of the MMPI (HSS) but were without a hereditary disposition for major psychiatric disorders. 32 sex- and age-matched college students were used as controls. Subjects whose T scores were higher than 70 were designated the HSS subjects. ERPs were recorded during an auditory oddball task. Although neither the P300 latencies nor the P200 latencies differed between the two subject groups, the amplitudes of P300 to rare stimuli and P200 to frequent stimuli were lower in the HSS subjects than in the controls. These results suggest that deficits, both in the P300-related cognitive function to rare relevant stimuli, as well as matching and/or the comparison process for irrelevant frequent stimuli, may be present in HSS subjects. The HSS subjects, especially those with a combination of P300 and P200 deficits, even though without a hereditary diathesis for schizophrenia, may constitute one type of high-risk group.

AERPs and clinical evolution of thought disorders over five years

In a selective attention task, 21 Subjects detected rare randomized targets (P = 0.02) in a set of randomized standard tones. In one condition, Subjects focused their attention and detected targets in one ear, ignoring the other ear, and vice versa in the next condition. AERPs (auditory event-related potentials) were recorded at 5 electrode sites (10-20 system), at Fz, Cz, Pz, C3, C4, in two conditions varying speed of stimulation (randomized interstimulus intervals of 250-750 ms and 750-1500 ms). One group of 7 schizophrenics with the major syndrome of formal thought disorder (+FTD) was compared to 7 schizophrenics without the FTD syndrome (-FTD), and to 7 controls. The schizophrenic group was matched for age, education, sex, medication, hospitalization and intelligence score on abbreviated WAIS test. Ss were re-tested after 5 years following identical experimental and counterbalancing method to the pre-test. At re-test, similarly to pre-test, schizophrenics' AERPs showed smaller amplitudes, longer latencies, smaller attention effects than normals. -FTD schizophrenics showed intermediate values between the +FTD patients and normals. At retest, +FTD schizophrenics showed an aggravation of these AERP abnormalities while -FTD patients seemed to improve with larger amplitudes, faster latencies and better attention effects than at pre-test. Differential correlations between clinical and AERP indices indicated a dissociation between neurophysiological and clinical evolution: factors of dissociation included Andreasen's positive and negative indices of thought disorder, neuropsychological indices on the Luria-Nebraska scales, and severity of psychotic symptoms.

Behavioral markers of schizophrenia useful for genetic studies

The advent of powerful molecular biological techniques have already led to the discovery of chromosomal loci linked to some genetically transmitted diseases. These techniques, however, lose their power if applied to a disease trait that is not Mendelian in its transmission. The low familial prevalence of psychiatric diseases such as schizophrenia make these techniques unsuitable for linkage studies of these conditions, if identification of schizophrenia relies solely on the clinical manifestation of the schizophrenic psychosis. Broadening the disease phenotype in diseases such as schizophrenia, with low recurrence risk, and narrowing it in diseases such as major affective disorder, with very high recurrence risk, may be an effective strategy for linkage studies of these diseases. Several alternative phenotypes are discussed, including smooth pursuit eye movement abnormalities, event related potentials, and deficient attentional deployment as measured by the continuous performance test. The strategy assumes that schizophrenia is a pleiotropic disorder, and that the psychosis is the rare form of the condition. The paper focuses principally on smooth pursuit eye movement abnormalities, and claims a plausible place for them as an independent expression of schizophrenia. With this strategy, the possibility for successful linkage studies increases, since familial distributions of schizophrenia and pursuit abnormalities, considered together, appear to fit an autosomal dominant pattern.

Unimodal and crossmodal reactivity in autism: presence of auditory evoked responses and effect of the repetition of auditory stimuli

Using auditory evoked responses, this work compares the reactivities to unimodal and crossmodal stimuli and the main neurocognitive functions most often disturbed in autism. With the aim of testing the hypothesis that the deficit in the ability to form crossmodal associations in autism is linked to a cognitive abnormality, auditory evoked responses to simple and to crossmodal (auditivo-visual) stimuli were recorded in 30 autistic children and compared with those of 30 normal and 30 mentally retarded children. Relationships between electrophysiological reactivity and neurocognitive functions showed that the cognitive deficit in the ability to maintain crossmodal associations is preceded by a more elementary perceptive abnormality in autistic children.

P300 and conceptual loosening in normals: an event-related potential correlate of "thought disorder?"

Reduced amplitude of the P300 component of the event-related potential (ERP) has frequently been reported in schizophrenic patients and their first-degree relatives. The present study examined the relationship between this ERP measure of attentional processing and loosening of associations in normal university students (termed "allusive thinking"). Among male subjects, scores reflecting increased conceptual loosening, measured using the Lovibond scoring method for the Goldstein-Scheerer Object Sorting Test (OST), were significantly correlated with smaller P300 amplitude recorded during an auditory target detection task. There was no association between OST score and either performance of the target detection task or self-reported psychopathology. It is suggested that reduced P300 amplitude could reflect altered attentional processing in individuals with a constitutional trait factor of thought disorder.

P300 in first degree relatives of schizophrenics

It has been reported that the amplitude of P300 is low in schizophrenic patients and high risk children. We recorded P300 components of the event-related potentials in first degree relatives of schizophrenic propositi who were considered to be over the age limit of the risk period for manifestation of schizophrenia and compared them with those of schizophrenic patients and controls. Both the first degree relatives and the schizophrenic patients showed lower P300 amplitude than the controls. There was no significant difference between the first degree relatives and schizophrenic patients in the P300 amplitude. These results would indicate that a low P300 amplitude is a trait marker for schizophrenia.

Endogenous event-related brain potentials and psychometric performance in children at risk for schizophrenia

Two independent groups of high-risk children for schizophrenia and their matched control children were submitted to the following experiments: an auditory oddball paradigm registrating late event-related potentials (ERPs) and a psychometric test battery including the assessment of Wechsler Intelligence Scales, reaction times (after regular and irregular preparatory intervals), and the d2-attention test. The study was intended to clarify whether long-latency ERPs and the selected psychometric tests would contribute to reliably differentiating between these groups. The results showed significantly prolonged latencies of the P3 component of the ERPs to rare, task-relevant target stimuli in both high-risk groups compared with the controls. Similarly, the N2 latencies were delayed in both groups. By contrast, ERP patterns to frequent, nontask-relevant stimuli were very similar, with no significant differences between high-risks and normals; nor did any ERP amplitudes show significant differences. The data are interpreted as a reflection of a subtle deficit in maintaining attention and a subsequent impairment of stimulus discrimination in high-risk children. This is consistent with the psychometric findings of higher error scores in target counts and d2-test, and significantly prolonged reaction times after regular preparatory intervals (PIs) in the high-risks. The findings may hint at a vulnerability for schizophrenia in high-risk children. Given the high prevalence of the attentional dysfunctions in both high-risk groups, however, it is hypothesized their presence does not necessarily imply an unequivocal manifestation of schizophrenia.

The P300 component of the auditory event-related potential in monozygotic and dizygotic twins

The P300 component of the auditory event-related potential was recorded from 10 pairs of monozygotic (MZ) twins and 11 pairs of dizygotic (DZ) twins during an auditory discrimination task. The within-pair similarity of P300 latency was significantly greater in MZ than in DZ twins. The within-pair similarity of P300 amplitude was not significantly greater in MZ than in DZ twins. These results support previous findings suggesting that P300 latency is largely genetically determined.

Neurological soft signs in schizophrenia

A standardised clinical examination which focused on neurological soft signs (NSS) was used by a neurologist blind to diagnosis to assess the presence of neurological soft signs. A comparison of NSS score was made among three groups of subjects consisting of 58 DSM-III schizophrenics, 31 of their healthy first-degree relatives and 38 normal controls. The schizophrenic group had significantly higher NSS total scores than normal controls but did not differ significantly from their first-degree relatives' group. The relatives' group showed higher NSS total scores than did normal controls although to a lesser extent than schizophrenics.

Normal variation of P300 in children: age, memory span, and head size

The P300 (P3) event-related brain potential was elicited in a group of 50 children and young adults (4-20 years). A simple auditory task was employed in which subjects indicated with a finger movement when a randomly occurring target tone (high pitch) was presented in a series of standard (low pitch) tones. The probability of the target tone was varied across conditions at 10%, 30%, or 50% to assess possible developmental changes in P300 amplitude. Memory capacity was assessed with forward and reverse digit spans. Circumference of the head also was measured. P300 latency decreased with age, and P300 amplitude tended to become larger with age. Polynomial regression analyses revealed significant quadratic trends in these relationships, with changes leveling off for older subjects. Digit span and head circumference also were related curvilinearly to P300 values. Multiple regression analysis indicated that changes in age and memory span both predicted significant changes in P300 latency and amplitude. Target stimulus probability generally affected all subjects in a similar fashion, although the strength of the correlational relationships tended to decline with increases in probability. Developmental changes for the N1, P2, and N2 components from the standard stimuli also were obtained. The results are discussed in terms of previous P3 findings for children and their implications for future studies.

P300 and smooth eye pursuit: concordance of abnormalities and relation to clinical features in DSM-III schizophrenia

Twenty-five DSM-III-diagnosed schizophrenics and 37 normal and age-matched controls were examined using an oddball paradigm for the generation of P300 and smooth eye-pursuit tasks. Results were compared between groups and related to clinical characteristics, including a family history of psychiatric illness. Group differences were found for P300 amplitudes, latencies and eye-tracking. A family history of psychiatric illness was associated with normal eye-tracking in patients. Small P300 amplitudes alone and in combination with long P300 latencies were associated with a family history in controls.

Signal detection indices in schizophrenics on a visual, auditory, and bimodal Continuous Performance Test

Signal detection indices (perceptual sensitivity) were calculated to compare performance of 24 male schizophrenic inpatients and 24 controls (12 alcoholics and 12 normals) on 4 different CPT-tests. A standard version (St) employed 1 target (P = 0.166) and 5 nontargets. In condition V stimuli were presented visually, in condition A acoustically and in condition VA bimodally (1 target (P = 0.333) and 1 nontarget). Compared to controls schizophrenics exhibited lower levels of perceptual sensitivity in all 4 conditions. They were especially impaired when stimuli were presented either acoustically or when they had to monitor 2 modalities simultaneously. Perceptual sensitivity of schizophrenics was significantly lower in conditions V, A, and VA than in condition St. For controls only condition VA led to lower values. Because St was always presented first, the possible explanation that vigilance decrement over time is responsible for the lowered perceptual sensitivity had to be ruled out. It could be shown that schizophrenics did not differ in sensitivity between conditions being later in task sequence. Controls, however, showed a slight decrement over time. Thus our finding should to a large extent be attributed to different task requirements. Response criterion beta yielded inconsistent results.

Prolonged latencies of the N2 and P3 of the auditory event-related potential in children at risk for schizophrenia. A preliminary report

In previous studies investigating long latency components of the event-related potential (ERP), schizophrenic patients generally showed reduced P3 amplitudes and in some studies prolonged N2 or P3 latencies. As there is a higher risk of offspring of schizophrenics than of mentally healthy parents developing this disease, the present study was intended to clarify whether ERP components (in particular the N2 and P3) differ between these two groups of children. Twelve high-risk and 12 age-matched control children (aged 9-16 years) performed an auditory oddball task in order to assess late ERP components. This task required the subject to covertly count rare target tone pips (P = 0.2) irregularly interspersed among frequent standard tone pips (P = 0.8) in two series of 400 pips. ERPs were recorded from midline electrodes (Fz, Cz, Pz). The results indicated distinctly prolonged N2 and P3 latencies in ERPs to target stimuli in children of schizophrenic patients. These findings suggest a slowed target classification in these children.

Childhood developmental changes in the auditory P300

In this study we investigated developmental changes in the auditory P3 latency from childhood to adolescence. Event-related potentials evoked by improbable auditory stimuli were recorded from 35 normal children between the ages of 5 and 13 years. Regression analyses showed significant age trends in the auditory P3 latency. Latencies decreased at a rapid rate (Cz: 20.34 msec/yr; Pz: 19.27 msec/yr) from childhood to adolescence, suggesting an increased efficiency in processing information as children mature. This rate was linear or constant in nature as evidenced by the failure of the quadratic and cubic components to significantly increase predictability of the regression equation. The slope of the P3 latency/age regression line was also shown to be influenced by the interactive effects of task difficulty and maturation. It was hypothesized that neuro-developmental processes (increased myelination and dendritic arborization) may underlie the maturational changes observed in the P3 latency during childhood.

[Treatment of schizophrenia: a new synthesis of the literature]

One can say that a new approach of long-term treatment of schizophrenia is born. In the last years many authors developed a psychoeducational point of view based on the concept of expressed emotions. These works are quite unknown by the French psychiatrists. However, this new way of treating schizophrenics is a very complete pattern. It includes and integrates many datas from psychophysiology to family functioning and seems very promising. The main studies are presented and discussed here.

Auditory event-related potentials in children at risk for schizophrenia: the complete initial sample

Event-related potentials (ERPs) were recorded from children of schizophrenic parents, children of parents with affective disorders, and children of parents without a history of psychiatric illness. ERPs were elicited during a modification of the "oddball" paradigm, in which two infrequents (a change in pitch and a missing stimulus) were embedded in a series of frequent background events. The data were recorded from electrodes located at midline frontal, central, parietal, and occipital scalp sites. Diagnostic assessments of the parents were performed using the Schedule for Affective Disorders and Schizophrenia-Lifetime Version (SADS-L) and Research Diagnostic Criteria (RDC). Behavioral assessments of the children were made with a modified version (BGAS) of the Global Assessment Scale. ERP amplitudes for several electrophysiological events were compared among groups for target and nontarget stimuli using analyses of of variance of both factor score and baseline to peak measures. No systematic differences suggesting waveform abnormalities in the children of schizophrenic parents (high-risk subjects) were found. However, when the results were analyzed using only those children whose parents had a "pure" diagnosis of either schizophrenia or affective disorder, the children of affectively disordered parents (psychiatric control subjects) showed significantly lower N100 amplitudes (to the frequent event only) than either the normal control or high-risk subjects. No consistent behavioral differences among the three groups emerged. Since only a small percentage of children at risk will eventually develop schizophrenia, ERP amplitude frequency distribution analyses were also performed and compared among groups. However, these did not provide evidence of an outlying subgroup in any of the three groups. There were complex relationships between ERP component amplitudes and behavioral adjustment in adolescence but, in general, these did not distinguish high-risk and psychiatric control subjects from each other. There was no evidence of a relationship between deviant attentional functioning as measured in an earlier round of laboratory testing and ERP late component amplitude.

Auditory evoked responses and their modifications during conditioning paradigm in autistic children

Auditory evoked responses (AERs) were recorded from 16 autistic children (ages 2-10 years) and age-matched normal and retarded controls. In order to test the ability to form auditory-visual cross-modal associations, often impaired in autism, the effects on AERs of coupling sound and light were studied with a paradigm that did not require the cooperation of the subject. Several differences between groups were found concerning the frequency and the amplitudes of present AERs. The pattern characterizing the effects on AERs of coupling sound and light (conditioning phenomenon) was observed for both autistic and normal controls, and not for retarded children. Results suggest that autistic children may have a real but slow learning ability.

P3 amplitudes in two distinct tasks are decreased in young men with a history of paternal alcoholism

Visual event-related potentials (ERPs) were obtained in two groups of young adult male subjects: One group (N = 24) considered to be at high risk for alcoholism due to paternal alcoholism and the second group (N = 26) with no family history of alcoholism. Results presented here were obtained during a baseline (no drug) condition. The ERP tasks both were target detection paradigms, but differed in several respects. One paradigm involved continuous participation in a distracting tracking task, but used an easily interpreted target stimulus. The second task involved no distractions, but entailed more complex stimuli. Both paradigms utilized level of task difficulty as an experimental variable. The results from both tasks were quite similar and demonstrated significantly lower ERP amplitudes in the high risk compared to the low risk group. Reaction times to target stimuli did not discriminate group membership, but were related to perceived task difficulty. Task difficulty was not a useful variable in discriminating group membership.

High-risk research in schizophrenia: a summary of what has been learned

High-risk research on schizophrenia has been concerned chiefly with two types of issues: (1) description of background factors in the early lives of high-risk subjects; and (2) identification of biological variables that may be markers of the genetic liability to schizophrenic disorders. It is concluded that efforts to describe background factors have led to some conflicting results, have shown little evidence of specificity of the factors under study to risk for schizophrenia, and may not be generalizable to most individuals who develop schizophrenia. Results of research focusing on biological variables are summarized under the headings of attention and information processing (AIP), smooth pursuit eye movement (SPEM), neurological signs, electrodermal responding, event related potentials, and ventricular size. Of these, certain AIP and SPEM dysfunctions show substantial evidence of serving as biological markers, certain other AIP impairments are promising in this regard, electrodermal responsivity is not, and the other three categories present uncertain or conflicting results. Several methodological issues that have hampered the first generation of high-risk research are discussed.

Event-related potentials in children at risk for schizophrenia during two versions of the continuous performance test

Event-related potentials (ERPs) were recorded from children of schizophrenic parents, children of parents with affective disorders, and children of parents without a history of psychiatric illness. ERPs were elicited during two versions of the continuous performance test (CPT), which differed in their level of processing complexity. The data were recorded from electrodes located at midline frontal, central, parietal, and occipital scalp sites. Diagnostic assessments of the parents were performed using the Schedule for Affective Disorders and Schizophrenia-Lifetime Version and Research Diagnostic Criteria. Clinical assessments of the children were made with a modified version of the Global Assessment Scale. ERP amplitudes for six electrophysiological events were compared among groups for target and nontarget stimuli using analyses of variance of both factor score and baseline to peak measures. There was one isolated between-group finding: frontal negative slow wave recorded at FZ was of greater magnitude in the high risk (HR) than in either the psychiatric (PC) or normal control (NC) groups. Since only a small percentage of children at risk will eventually develop schizophrenia, ERP amplitude deviance and frequency distribution analyses were also performed and compared among groups. ERP component amplitudes did not distinguish the groups when each component was considered separately. Deviance analyses, using a combination of the amplitudes of the six ERP components, also did not provide evidence of a deviant subgroup within any of the three groups. There appeared to be no relationship between ERP component amplitudes and behavioral adjustment in adolescence. Some evidence of a relationship between deviant attentional functioning and ERP component amplitude was found, but the pattern of findings within the attentionally deviant HR subgroup was opposite to that found for the HR group as a whole and more consistent with the pattern found for the NC group.

Images of the brain in psychiatry

In psychiatry, the use of computer-based techniques for constructing images of the brain is relatively recent. Nevertheless, findings that have resulted from their use thus far might provide us with a new perspective in the understanding of mental illness. They raise the possibility that many of the disorders, previously understood primarily in terms of psychosocial factors, are associated with specific abnormalities of brain structure and/or function. Although terms such as NMR, BEAM, RCBF, SPECT and PET are increasingly found in medical and psychiatric journals, few people understand in simple terms the principles on which these techniques are based. In this article the techniques used for constructing images of brain structure and function are explained, and an overview of the findings in psychiatric disorders is presented.

Electrodermal recovery data on children of schizophrenic parents

Half-amplitude recovery of electodermal responses is compared in children of schizophrenic parents (high-risk subjects) and children of depressed or normal parents. The results are dissimilar to those reported by Mednick and colleagues on a Danish high-risk sample. No significant differences emerged among the three groups in our study. Recovery did not differ according to sex or severity of illness of the schizophrenic parent. Recoveries of high-risk subjects separated from their homes were not shorter than recoveries of subjects who remained home. Recovery time recorded in childhood was unrelated to global adjustment in adolescence.

Biobehavioral risk factors in children of schizophrenic parents

Research on risk factors for schizophrenia is reviewed with emphasis on children of schizophrenic parents. As children of schizophrenic parents are not representative of the majority of individuals who become schizophrenic, examination of variables such as those relating to home environment or parental characteristics in these children is not expected to contribute greatly to an understanding of risk for schizophrenia or to the search for early indicators of a genetic liability, whereas study of selected biobehavioral variables may do so. Four areas of biobehavioral functioning that have been examined in high-risk research are discussed. Three of these are considered to be compatible with the hypothesis of a neurointegrative defect underlying schizophrenia-proneness and to be promising for further research.

Children of disturbed parents: the interface between research and intervention

This paper provides a review of high-risk studies and preventive interventions with children who have an increased likelihood of developing psychopathology because they are the offspring of emotionally disturbed parents. The research implications for preventive interventions are summarized in terms of selection of participants, goals for prevention, intervention methods, and intervention research methodology. Next, several preventive intervention programs are reviewed and evaluated for their responsiveness to the research literature. The review revealed that, despite theoretical and methodological diversity in the research literature, the findings provide many suggestions for the design of preventive interventions. On the other hand, intervention programs were most often found to have not used research findings in program design. This review concludes with suggestions for needed research and guidelines for future preventive interventions.

Event-related potential concomitants of information processing dysfunction in schizophrenic children

ERPs were recorded from 10 schizophrenic and 13 normal children during the performance of the Span of Apprehension task (Span). This task involves the discrimination of a randomly placed target letter among distractors, and it has been shown to discriminate between normal and schizophrenic individuals. The EEG was recorded at 7 scalp loci, and ERPs were averaged over a 1500 msec interval initiated by a warning tone which preceded the visual Span stimuli by 500 msec. Stimulus arrays were grouped into 4 levels of difficulty. The data from both subject groups were combined in a single principal components analysis (separate PCAs exhibited few differences between groups) generating 8 rotated factors which were readily interpreted in terms of conventional ERP components. Factor scores for the two groups were examined using Analysis of Variance. The schizophrenic children produced a small CNV which was slow to develop and resolve as well as diminished amplitudes for the N1, P3 and slow wave components. This suggests that these children are impaired in their ability to regulate processes involved in the mobilization and direction of attention and the discrimination of target stimuli. Significantly, the schizophrenic children did not show progressive increases in N1 and SW amplitudes in response to increases in information processing demand (array difficulty) as was the case in the normal children. ERP components of the schizophrenic children were most aberrant at frontal leads, but midline and lateralized deficits were also seen at vertex and posterior recording sites.

Dopamine and schizophrenia: an analysis of the theory

The postulated relationship of dopamine to schizophrenia ranks among the most important contemporary theories pertinent to the biological bases of behavior. However, as an examination of the relevant research literature makes clear, the theory has not yet been convincingly validated. This lack of validation is due, in part, to a failure to address the following questions: Is dopamine hyperactivity an etiological and/or a symptom factor in schizophrenia; do laboratory measures used to test the theory truly parallel the relevant clinical phenomena; is attenuated dopamine activity a necessary and/or sufficient condition for remission of schizophrenic symptoms? Analysis of these questions not only provides a departure point for examining the theory, but sets the stage for a reformulation of the theory itself.