Brain evoked potential in schizophrenic patients

The authors reviewed the literature on evoked potentials in mentally ill patients, with particular emphasis on schizphreniacs. The commonly observed abnormalities were as follows: 1) higher SEPs amplitudes with less waveshape variability during first 100 ms in non-depressed chronic, paranoid or undifferentiated patients with florid psychotic symptoms; normal SEPs amplitudes in acute or latent schizophrenics and in chronic depressed schizophrenics but without florid psychotic symptoms; 2) reduced SEPs and VEPs amplitude recovery and faster latency recovery; 3) reduced AEPs amplitude and latency; 4) greater VEPs waveshape variability and tendency to be "reducers" in hallucinating patients; reduced amplitude and latency recovery; prolonged latencies in patients with positive family history (schizophrenia or affective disorders in close relatives); prolonged N2 latency in motor responses to "easy" and "difficult" stimuli; reduced activity of "late potentials"; 5) greater waveshape variability in all modalities in chronic schizophrenics, abnormal P300 (reduced amplitude, lack of P300 or negative "effect of uncertainty") and abnormal CNV (less "readiness" potential, prolonged negativity with motor responses).     

Emotional experience and expression in schizophrenia and depression.

Examined the emotional responses of schizophrenic, depressed, and normal Ss and whether differences in the emotional responding of these groups depended on how emotional responses were elicited or measured. 23 blunted and 20 nonblunted schizophrenics, 17 unipolar depressed Ss, and 20 normal Ss were exposed to a series of affect-eliciting stimuli. The stimuli varied in valence (positive vs negative) and in level of cognitive demand. Ss reported their subjective experiences, and their facial expressions were videotaped. Blunted schizophrenics were the least facially expressive, although their reported subjective experiences did not differ from those of the other groups. The nonblunted schizophrenics were more responsive than the depressed Ss to the positive stimuli, although the 2 groups did not differ in their clinical ratings of affective flatness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

P300 in schizophrenia: interactions between amplitudes and topography

Low P300 amplitudes and topographical asymmetries have been reported in schizophrenic patients, but reference-independent amplitude assessment failed to replicate reduced amplitudes. P300 amplitude is conventially assessed at midline electrodes (Pz), and asymmetric topography as reported in schizophrenics, may confound this measurement. We investigated the possible interaction between P300 topography and assessments of amplitudes. In 41 clinically stable schizophrenics and 31 normal controls, the general finding of reduced amplitudes at the Pz-electrode and topographical asymmetries in the patient group were replicated. In both groups, asymmetries of the P300 field (lateralized peaks) reduced the standard amplitude assessment at the midline parietal electrode, but did not affect the reference-independent, global amplitude assessment. This shows that asymmetry per se does not imply reduced field strength. In addition, in schizophrenics, but not in controls, there was a significant effect of the direction of asymmetry on both amplitude measures, amplitudes being lower with increasing shift of the P300 peak to the right side. Considering also the slightly left-lateralized peaks in the normal controls, this suggests that only right-lateralized P300 peaks express functional deficits in schizophrenics, whereas left-lateralized peaks fall within the physiological variability of the P300 field. The reference-independent amplitude assessment is proposed for unambiguous amplitude assessment in order to better define the clinical, psychological and physiopathological meaning of the P300 alterations in schizophrenics.     

Phasic electrodermal orienting response in chronic schizophrenics: II. Response to auditory signals of varying intensity.

Studied phasic electrodermal orienting response (OR) to brief tones at 60, 75, or 90 db. Results support earlier findings obtained with brief visual stimuli both in retest and in newly recruited Ss among 72 clear and 72 confused chronic schizophrenics and 48 normal controls. Confused Ss showed diminished reactivity to stimuli of low to moderate intensity. A moderate increase in stimulus intensity significantly improved initial OR frequency among confused Ss without affecting response amplitude; further increase brought initial OR amplitude to normal levels. Chronic schizophrenics again showed consistently faster habituation than controls. Results are not attributable to particular diagnostic subgroupings or total time in hospital. While long-hospitalized Ss with a hebephrenic diagnosis are more likely to be confused, it is the fact of confusion itself that is significant in determining OR. Results suggest faster but less detailed assilimation of information among chronic schizophrenics in general, coupled with a defensive attenuation of specific input among confused patients in particular. (30 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Another look at parastichies

The conditioning-testing (S1-S2) P50 auditory evoked potential (EP) has been well-documented and accepted as an important tool for measuring sensory gating in schizophrenia research. However, the physiological mechanism of the phenomenon is not known. In this study a single-trial analysis was used to determine the influence of the latency variability of the responses in the formation of the averaged P50. Ten schizophrenic patients and 10 normal controls were tested in the dual-click EP paradigm. Using ensemble averaging analysis, we replicated the previous finding of a lower S1 P50 amplitude and higher S2/S1 ratio in schizophrenics compared with normal controls. The single-trial analysis revealed that patients had significantly higher trial-to-trial latency variability in S1 responses than normal subjects, while the S2 showed the same variability as in controls. Measured by the single-trial procedure, the arithmetic mean amplitudes of P50 responses to S1 and S2 were similar between normal and schizophrenic subjects. The same measure also eliminated the difference in averaged P50 amplitude between S1 and S2 for both groups. Temporal variability appears to be an important factor in the assessment of averaged EPs and thus contribute to the change of P50 amplitude observed in schizophrenia.     

Schizophrenic deficit and its relation to social motivation.

A study investigating the effects of praise and encouragement on the performance of schizophrenics was carried out with 48 normal and 48 hospitalized schizophrenics, the latter being drawn equally from open and closed wards. All Ss performed a simple motor task, those in the experimental groups receiving verbal praise and encouragement from E after each trial and those in the control groups no evaluative comments. The results indicated that all experimental groups performed better than their controls but that the amount of improvement did not differ among the diagnostic groups. In absolute performance level, normals were significantly superior to the schizophrenics but the 2 schizophrenics groups did not differ significantly from each other. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information processing for masked and unmasked stimuli in schizophrenia and old age.

Compared 36 hospitalized schizophrenics, depressives, and normal elderly Ss (mean ages 24.7, 31.8, and 67.5 yrs) on tasks involving the identification of briefly exposed masked and unmasked stimuli. The critical stimulus duration (CSD), defined as the minimum exposure required to consistently identify a target stimulus without a mask, was obtained for each S. The target stimulus was followed by a pattern mask. Masking functions were estimated at 3 levels of exposure duration, including the S's CSD. At each exposure duration the mask followed at 4 interstimulus intervals. The elderly required longer durations for criterion identification of unmasked stimuli than the other Ss. For masked stimuli, however, the elderly did not differ from depressed inpatients, and both of these groups exceeded the schizophrenics when the test stimulus was exposed at Ss' CSD. Results indicate that when the initial availability of input information is controlled, schizophrenics show a mask-induced deficit relative to depressed inpatients, but the elderly do not. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of stimulus significance on the electrodermal response in chronic schizophrenia.

Skin conductance reactivity (SCR) to stimuli made significant for half of each sample and kept innocuous for the other half was compared in schizophrenics, normals, and alcoholics. In every case, trials began with a 5-sec slide presenting 4 words and ended 15 sec later with a recorded auditory presentation of one of these words. For half of each sample, stimuli were made significant by requiring Ss to retain the visually given words so that, on hearing the subsequent spoken word, they could immediately repeat one of the words in the last-seen slide other than that just heard (report condition). The remaining Ss only had to sit still and do nothing (simple condition). As predicted, schizophrenics showed smaller, faster habituating SCRs than controls only in the simple condition and resembled controls when the same stimuli were made significant in the report condition. Words were slected a priori for delusional, alcoholic, and neutral content to see whether this would affect SCR. Posttest interviews indicated that the a priori selections were not successful in establishing differential significance, and SCR accordingly did not vary with content in any group. In all groups, introducing explicit significance increased SCR amplitude, slowed habituation, and heightened spontaneous fluctuation frequency to both visual and auditory stimuli, but did so most markedly to the auditory signals that were closer in time to the significance-creating report. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scales for physical and social anhedonia

Devised 2 true–false scales to measure anhedonia, the lowered ability to experience pleasure: a 40-item Physical Anhedonia (PA) scale and a 48-item Social Anhedonia (SA) scale. After scale development using 371 college students, the final version was given to 505 normal adults stratified by social class, age (18–45), and sex, and to 123 male schizophrenics. The potential artifacts of social desirability, acquiescence, and random responding were ruled out. Coefficient alpha values for PA and for SA were .74 and .85 for male normal Ss and .82 and .85 for male schizophrenics. Schizophrenics scored more anhedonic than normal Ss on both PA and SA. Schizophrenics' scores on PA fell into 2 clusters of scores, one resembling the total distribution of the normal Ss, and a 2nd cluster consisting of scores that were more anhedonic than those of the normal Ss. Anhedonics were more often poor premorbid and hedonics more often good premorbid. The PA scale may be useful for testing the hypotheses, advanced by several theorists, that anhedonia is genetically transmitted and that nonpsychotic anhedonics are at high risk for schizophrenia. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Creativity and schizophrenia: An equivalence of cognitive processing.

Two tests of creativity were given to 10 paranoid and 10 nonparanoid schizophrenics, 10 nonpsychotic psychiatric controls, and 10 normal Ss. Ss were aged between 18 and 50 yrs. Scores on vocabulary and similarities tests, as well as education, medication, marital status, socioeconomic background, and age, were examined. Results indicate that nonparanoid schizophrenics were significantly more creative than paranoids and psychiatric controls on one creativity measure, a graded level measure of the Alternate Uses Test. Also, nonparanoid schizophrenics produced a significantly higher percentage of "highly creative" responses than did normals. Nonparanoid schizophrenics also scored higher than the other groups on the Welsh Figure Preference Test, but this finding was found to be related to age rather than to schizophrenia. The superior performance of the nonparanoid schizophrenic is discussed in terms of the encouragement that a supportive, nonjudgmental testing environment provides. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Number and position of visual stimuli as determinants of reaction time in schizophrenia.

Notes that RT in normal Ss has been shown to be linearly related to stimulus complexity, defined as the log of the number of equally probable stimuli to which a response may be made. Data from an earlier study of 40 short- and long-term paranoid and nonparanoid male schizophrenics and 10 male hospital employees were reanalyzed and compared with P. Venable's (see record 1959-10789-001) study of schizophrenic deficit. Although experimental procedures were dissimilar, both studies found that increased complexity did not result in schizophrenics having steeper regression slopes than normal Ss. Consideration of the position of the critical stimulus, however, clearly indicated that long-term, nonparanoid schizophrenics narrow attention to central cues when confronted by an increase in complexity. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time-linked impairment in schizophrenic reaction time performance.

Reports on the disruptive influence of uncertain visual probe stimuli on schizophrenic reaction time performance as a function of both the time since the onset of the probe stimuli and the pathology level of the Ss. Two studies were conducted, using 32 process schizophrenics, 16 reactive schizophrenics, 16 nonschizophrenic patients (alcoholic, immature personality, and depression diagnoses), and 16 normal controls. Mean ages of Ss ranged from 28.2 to 37.1 yrs. Probe trials were imbedded within standard series of regular reaction time trials. Both process and reactive schizophrenics were impaired by this stimulation on trials with only a 1-sec preparatory interval. Process schizophrenics showed impairment at the longest (9-sec) trials following recovery at midrange durations. The midrange recovery and long trial impairment of the process schizophrenics was a pattern strongly related to degree of pathology. The same U-shaped pattern—early and late impairment with intermediate recovery—and a similar relationship of the reaction time pattern to pathology level were found again in a 2nd sample of process schizophrenics who were given less intense visual stimulation on the probe trials. The U-shaped patterns obtained for the process schizophrenics in both studies are thought to reflect inadequate modulation of inhibitory controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Body-image aberration in schizophrenia.

A 28-item true–false scale was constructed to measure schizophrenic body-image aberration. The scale was standardized on both 631 male and 718 female college students and 100 male noncollege normal controls (mean age 31.7 yrs). The 74 male schizophrenic Ss reported more body-image aberration than normal nonstudent Ss, but only a portion of the schizophrenics were deviant. 20 male nonpsychotic clinic clients did not have heightened scores. Correlational findings indicate that schizophrenic body-image aberration is an aspect of a broader perceptual aberration. Scores on body-image aberration were negatively correlated with time since first hospitalization. The Body-Image Aberration Scale had essentially no correlation with the Physical Anhedonia Scale (L. J. Chapman, J. P. Chapman, and M. L. Raulin) for schizophrenics. For nonschizophrenics, however, high scores on the 2 scales accompanied one another significantly less often than expected by chance. It is suggested that the 2 scales may identify alternative manifestations of proneness toward the same schizophrenia. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal abstracting ability and schizophrenia.

The Benjamin Proverbs Test was administered to 3 groups of 40 Ss each: reactive schizophrenics, process schizophrenics, and normal control Ss. Patients were rated for prognosis using the Premorbid subscale of the Phillips Prognostic Rating Scale. Ss were matched for education, vocabulary, age, and socioeconomic status of father. Proverbs were scored by 3 judges working independently. Highly significant differences were found among the 3 groups in ability to interpret proverbs. Process schizophrenics showed the greatest degree of impairment; reactive schizophrenics showed significant impairment, as compared to normal controls, but significantly less impairment than did process schizophrenics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Residual performance deficit in clinically remitted schizophrenics: A marker of schizophrenia?

The study of remitted schizophrenic outpatients is proposed as a way of minimizing the effects of the "nuisance variables" that confound the study of hospitalized schizophrenics. 20 hospitalized acutely disturbed schizophrenics (mean age, 37.0 yrs), 20 schizophrenic outpatients in clinical remission (mean age, 42.8 yrs) and 20 normal controls (mean age, 35.1 yrs) were administered a span of apprehension test and the Continuous Performance Test (CPT). All Ss were controlled for sex and WAIS scores and schizophrenics were rated with Phillips Prognostic Rating Scale. On the CPT, both acute and remitted schizophrenics made significantly more errors of omission and commission than did the normal controls. On the span of apprehension, both groups of schizophrenics showed a significantly greater decrement in accuracy of detection of the target stimuli than did normal controls. The same pattern of results has been observed in children at risk for schizophrenia, which suggests that the span of apprehension may be sensitive to core schizophrenic processes that are independent of clinical state. The cross-sectional study of the 3 stages of schizophrenia—the premorbid, acute, and remitted—is proposed as a way of identifying "core" schizophrenic processes and markers of vulnerability to schizophrenia. The adequacy of a general "attentional impairment" interpretation of schizophrenic deficit is questioned. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression, schizophrenia, and social attraction.

J. C. Coyne (see PA, Vol 56:02455 and 61:1146) has shown that after interacting with depressed patients, Ss report feeling depressed themselves and rejecting toward the depressed person. In the present study, measures (e.g., Mood Adjective Check List, Interpersonal Check List) were obtained from 216 undergraduates who listened to tapes of interviews with either hospitalized depressive, hospitalized schizophrenics, or normal hospital staff. Results show that schizophrenics aroused dysphoric feelings similar although not identical to those feelings aroused by depressives, and in the case of males they were equally rejected. In addition, the schizophrenics and, to a lesser extent, the depressives were seen as weak, submissive, and less capable of offering a positive relationship. Modifications of the Coyne position are suggested. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of self-esteem lability and low trait self-esteem as vulnerability factors for depression.

Self-esteem lability (SEL), defined as daily event-related variability in state self-esteem, and low trait self-esteem (TSE) were assessed among 205 male and female undergraduates who were currently depressed, previously depressed (PD), and never depressed (ND). SEL scores were derived for the effect of positive, negative, and combined events on state self-esteem over 30 days. Consistent with psychodynamic and cognitive theories, SEL was found to be a better index of depression proneness than TSE. PD Ss showed higher lability on all SEL scores than ND controls but did not differ from controls on TSE. Ss were reassessed 5 mo later, and new cases showed higher premorbid SEL than ND controls but did not differ from controls on premorbid TSE. SEL at Time 1 was found to increase risk for depression at Time 2 among Ss reporting high life stress at Time 2. Theoretical and methodological implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual information-processing deficits in chronic schizophrenic subjects using tasks matched for discriminating power.

Compared the performance of 24 18–52 yr old hospitalized schizophrenics with that of 18–48 yr old normal controls on 3 matched visual information-processing tasks. Each of the 3 tasks involved deciding on the relative magnitude of 2 groups of letters. The 2 experimental conditions, one in which irrelevant distracting stimuli were added and the other in which response demands were increased, were matched for discriminating power with a neutral condition. Results show a significant reaction-time difference between groups on all 3 tasks, implying an overall reduction in processing speed among schizophrenics. However, schizophrenic Ss were not specifically sensitive to the effects of visual distraction or increased response complexity. Data are consistent with theories of schizophrenic deficit that emphasize the generalized nature of the cognitive disturbance and relate the level of deficit on particular tasks to the amount of capacity required to complete processing. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organization in memory: A comparison of psychotics and normals.

15 acute schizophrenics, 11 acute psychotic depressives, and 15 normal Ss completed a multitrial free-recall task. The 30 to-be-remembered nouns from 6 conceptual categories were printed, 1 on each card. During self-paced presentation, the nouns were sorted into S-determined categories. Patient recall was inferior. The extent to which successive categorizations of the words during sorting were similar and reflected norms of category membership was measured. No significant group differences were realized. Patient recall clustering, defined both by norms of category membership and subjective sorting categorizations, was inferior. On no measure did schizophrenics and depressives differ. Results indicate that with lists of relatively high semantic content, the recall impairment displayed by schizophrenics and depressives stems mainly from an inability to completely use perceived structuring of the list during recall. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)