Reduced or increased influence of non-pertinent information in patients with schizophrenia?

We tested the ability of 18 patients with schizophrenia and 18 matched controls to filter non-pertinent information in orientation matching tasks. The non-pertinent information consisted of pictures conveying semantic information. The pertinent information consisted of oriented line-segments drawn inside pictures or was represented by the overall orientation of the picture itself. The results showed that non-pertinent information interfered with performance of control subjects in all tasks. In contrast, non-pertinent information interfered with the performance of patients with schizophrenia to the same extent as that of matched controls only when non-pertinent and pertinent information was physically mingled, but not when they were separated. Yet, patients processed non-pertinent information in all experiments, as shown by reversed interference effects when non-pertinent and pertinent information was physically separated. These results suggest a deficit at linking physically distinct visual information in patients with schizophrenia. Additionally, performance was more impaired in patients with schizophrenia than in control subjects when the amount of displayed information increased. The results suggest the coexistence, and a possible relationship between attentional deficits and impairments at linking distinct visual information in patients with schizophrenia.     

Psychometrically matched visual-processing tasks in schizophrenia spectrum disorders

Patients with schizophrenia show deficits in visual perception and working memory, but the relationship between these deficits has not been characterized with psychometrically matched tasks. The authors administered 2 visual discrimination and 6 recognition tasks to 43 schizophrenia spectrum patients and 22 nonpsychiatric subjects. When performing difficulty-matched tasks, spectrum subjects showed more severe impairments for motion compared with form processing. When tasks were matched on true score variance, spectrum subjects exhibited worse performance on both form and motion discrimination, and a differential deficit in motion recognition with a short display duration and long interstimulus interval. These results provide evidence of differential deficits in visual processing in schizophrenia that appear to be dependent on the temporal characteristics of the tasks.     

Impaired Interpretation of Others’ Behavior is Associated with Difficulties in Recognizing Pragmatic Language in Patients with Schizophrenia

Much attention has been paid to the pragmatic language function in schizophrenia. This study of Japanese patients with schizophrenia examined the relationship between impaired interpretation of the behaviors of other people in social contexts and the ability to recognize metaphor and irony. We assessed 34 patients with schizophrenia and 34 normal subjects using first- and second-order theory of mind tasks, the Metaphor and Sarcasm Scenario Test, and the Dewey Story Test (which tests the ability to judge others’ social behaviors). We compared the performance between the groups and analyzed correlations between the tasks. All tasks revealed significant deficits in the patients compared with the controls. In the patient group, metaphor comprehension was correlated with the ability to judge normal behaviors, and irony comprehension was correlated with the ability to judge abnormal behaviors, suggesting that deficits of social cognition in schizophrenia include these two types of factors associated with pragmatic language.     

A comparison of implicit memory tests in schizophrenic patients and normal controls

The objective of the current study was to compare the performance of schizophrenic patients and normal controls on implicit memory tests. Two neuropsychological tasks were administered to 29 patients and normal participant samples. The implicit tests were: Word fragment completion and Word production from semantic categories. The priming score was the variable of interest. Priming effects are obtained in normal subjects and schizophrenia patients, regardless of the implicit test used. However, a dissociation in priming between normal and patient groups was observed, depending on the test used. For word fragment test, priming was identical between the two groups. However, for word production, priming obtained in schizophrenics was lower than priming in normal controls. Results confirm a dissociation effect in implicit memory tests. These results could be explained in the context of the Roediger and Blaxton (1987) distinction between data-driven and conceptually-driven processing. This evidence suggests that a complete neuropsychological assessment of memory in schizophrenia should include different kinds of implicit memory tests (procedural, perceptual, and conceptual tasks).     

Spatial frequency discrimination in schizophrenia

Pathways within the visual system can be distinguished on the basis of selectivity for low or high spatial frequencies. Spatial frequency discrimination was evaluated in 17 medicated male patients with schizophrenia and 19 male control subjects. Subjects were required to discriminate whether pairs of high contrast, sinusoidally modulated gratings were the same or different in spatial frequency. Accuracy performance was compared at high, medium, and low spatial frequencies on tasks matched for control performance. Patients showed a greater performance decrement of 12% on low as compared with 4% on high spatial frequencies. These findings suggest a disturbance of right hemisphere mechanisms involved in spatial perception and attention in schizophrenia.     

Comparison of Two Subtests of the Bay Area Functional Performance Evaluation

This study compared different versions of two subtests of an existing occupational therapy evaluation, The Bay Area Functional Performance Evaluation. The two subtests examined were the shell sorting task and the house floor plan. Modifications in these subtests were made in order to make the testing medium more relevant to the patients. The subjects were twenty patients with a diagnosis of schizophrenia and twenty normal controls. The age range of the subjects was between 20 and 39 years. The patients with schizophrenia and th,e normal controls were randomly divided and half of each group were administered the original subtests and half were administered a modified version. For each subject a time and an accuracy score was obtained. It was hypothesized that patients with schizophrenia would score more poorly than normal controls on both versions of the tasks, but that difference between groups would be less on the modified version of the tests. Results indicated that the patients witlh schizophrenia performed significantly more poorly (lower accuracy scores and longer time) than the normal controls on both the original two subtests and the modified versions. There was no group by task interaction. These results contribute to the validity of the ex.isting evaluation.     

Phonological deficits: Beneath the surface of reading-acquisition problems

Summary In Experiment 1, the performance of young retarded readers on speech-segmentation tasks was compared with the performance of normal subjects matched for chronological age (CA) and with subjects matched for reading age (RA). Retarded readers were poorer than both control groups in consonant deletion, while there was no difference between the groups on a rhyme-judgement task and a syllabic-vowel-reproduction task. In Experiment 2, another group of reading retarded children was compared with CA and RA controls on the classification of pseudowords, either by common phoneme or by overall phonetic similarity. The retarded readers made fewer classifications based on common phoneme than both control groups, while there was no difference between the groups in classifications based on overall phonetic similarity. In Experiment 3, adult developmental dyslexics were compared with normal adults in the tasks of Experiments 1 and 2. The dyslexics made fewer classifications based on a common phoneme than the normals, while no difference was found in classifications based on overall phonetic similarity.     

Habit and skill learning in schizophrenia: evidence of normal striatal processing with abnormal cortical input

Different forms of nondeclarative learning involve regionally specific striatal circuits. The motor circuit (involving the putamen) has been associated with motor–skill learning and the dorsolateral prefrontal cortex (DLPFC) circuit (involving the caudate) has been associated with cognitive–habit learning. Efforts to differentiate functional striatal circuits within patient samples have been limited. Previous studies have provided mixed results regarding striatal-dependent nondeclarative learning deficits in patients with schizophrenia. In this study, a cognitive–habit learning task (probabilistic weather prediction) was used to assess the DLPFC circuit and a motor–skill learning task (pursuit rotor) was used to assess the motor circuit in 35 patients with schizophrenia and 35 normal controls. Patients with schizophrenia displayed significant performance differences from controls on both nondeclarative tasks; however, cognitive–habit learning rate in patients did not differ from controls. There were performance and learning-rate differences on the motor–skill learning task between the whole sample of patients and controls, however, analysis of a subset of patients and controls matched on general intellectual level eliminated learning rate differences between groups. The abnormal performance offset between patients with schizophrenia and controls in the absence of learning rate differences suggests that abnormal cortical processing provides altered input to normal striatal circuitry.     

Sustained attention in children at risk for schizophrenia: Findings with two visual continuous performance tests in a new sample

In partial replication of an earlier study, 35 children at high risk for schizophrenia, 25 children at high risk for affective disorder, and 53 normal control children from a new sample of 7- to 12-year-old subjects were tested with two new visual continuous performance tests. Response levels and intrasubject variability were analyzed separately. Multivariate analyses on factor scores derived from response levels indicate that "groups" is a significant predictor for a factor reflecting discriminability (or sensitivity) for the more difficult of these tests but not for the less difficult one, and that high risk for schizophrenia is associated with lower performance. Factor scores and multiple regression analyses were used to dichotomize subjects as to whether or not they are low performance outliers. A significantly larger proportion of subjects from the high risk for schizophrenia group than from the control groups were low performance outliers. Among subjects that developed psychopathology in adolescence, subjects at high risk for schizophrenia were more likely to have contributed low performance outliers early during childhood.     

Subjective qualities of memories associated with the picture superiority effect in schizophrenia

Patients with schizophrenia (n = 24) matched with 24 normal subjects were presented with both words and pictures. On a recognition memory task, they were asked to give remember, know, or guess responses to items that were recognized on the basis of conscious recollection, familiarity, or guessing, respectively. Compared with normal subjects, patients exhibited a lower picture superiority effect selectively related to remember responses. Unlike normal subjects, they did not exhibit any word superiority effect in relation to guess responses; this explains why the overall picture superiority effect appeared to be intact. These results emphasize the need to take into account the subjective states of awareness when analyzing memory impairments in schizophrenia.     

Machiavellianism and Theory of Mind in people affected by schizophrenia

CONTEXT: People affected by schizophrenia show deficits in social interaction (Cramer, Bowen, & O'Neill, 1992); such a deficit may stem from an alteration in the representation of mental states. OBJECT: In this study we have examined 42 people affected by schizophrenia, diagnosed according to DSM-IV criteria, by testing them with an instrument (the Mach IV scale, Christie & Geis, 1970) assessing "Machiavellian Intelligence" according to Niccolò Machiavelli's assertions. Schizophrenic subjects were compared to a sample of normal controls, matched for age, sex, and education. OBJECTIVE: The aim of our study was to evaluate if there were correlations between the ability to understand other people's mental states and the capacity for interpreting "Machiavellian expressions." RESULTS: Results show that people affected by schizophrenia are less able to use Machiavellian-style "tactical" abilities than controls. CONCLUSION: Such a disability seems to be correlated to poor mentalising abilities.     

Reaction time to threat stimuli in panic disorder and social phobia

Two studies assessed response time among clinically anxious subjects and normal controls when presented with threat, positive and neutral stimuli under perceptual (lexical decision) and semantic (category decision) task conditions. In Study 1, panic disorder subjects' (n = 14) performance was compared to that of matched normal controls (n = 14) while in Study 2 social phobic subjects (n = 24) were compared to matched normal controls (n = 24). Relative to matched normal controls, panic disorder subjects but not social phobics tended to show greater slowing in performance on the more cognitively complex (category) task. A second finding, consistent across both studies was that, compared to the normal control groups, both panic and social phobic groups showed significantly slowed responses to threat words in both the perceptual and semantic tasks. Such findings are directly counter to the predictions of a mood congruence hypothesis. This apparent contradiction is resolved by a review of the literature which indicates that mood-related facilitation effects are obtained only in tasks which tap awareness of threat information rather than speed of response. It is suggested that while anxiety may produce enhanced awareness of threat, it may inhibit responsiveness to it. The results of these studies are seen as consistent with ethological theories of inhibited motoric responses under certain threat conditions. Furthermore, the findings suggest that caution is indicated in interpreting slowed reaction time to threat stimuli in tasks such as the Stroop color naming task as purely the result of attentional processes.     

Intact emotion–cognition interaction in schizophrenia patients and first-degree relatives: Evidence from an emotional antisaccade task

Schizophrenia patients have deficits in cognitive control as well as in a number of emotional domains. The antisaccade task is a measure of cognitive control that requires the inhibition of a reflex-like eye movement to a peripheral stimulus. Antisaccade performance has been shown to be modulated by the emotional content of the peripheral stimuli, with emotional stimuli leading to higher error rates than neutral stimuli, reflecting an implicit emotion processing effect. The aim of the present study was to investigate the impact on antisaccade performance of threat-related emotional facial stimuli in schizophrenia patients, first-degree relatives of schizophrenia patients and healthy controls. Fifteen patients, 22 relatives and 26 controls, matched for gender, age and verbal intelligence, carried out an antisaccade task with pictures of faces displaying disgusted, fearful and neutral expressions as peripheral stimuli. We observed higher antisaccade error rates in schizophrenia patients compared to first-degree relatives and controls. Relatives and controls did not differ significantly from each other. Antisaccade error rate was influenced by the emotional nature of the stimuli: participants had higher antisaccade error rates in response to fearful faces compared to neutral and disgusted faces. As this emotional influence on cognitive control did not differ between groups we conclude that implicit processing of emotional faces is intact in patients with schizophrenia and those at risk for the illness.     

The relationship of clinical, cognitive and social measures in schizophrenia: a preliminary finding combining measures in probands and relatives

This study examines performance of schizophrenia patients, unaffected relatives and controls in social cognition, cognitive and psychiatric scales looking for possible markers of vulnerability in schizophrenia. Performance of schizophrenia patients from multiplex families, first-degree relatives, and matched controls was compared and, subsequently, discriminant analysis method was used for identifying the best predictors for group membership. By using Multigroup Discriminant Analyses on the three groups, the best predictors were PANSS, Premorbid Adjustment Scale, Faux Pas test, and a face/emotion categorizing task. This model obtained 82% correct global classification, suggesting that the combination of psychiatric scales and neuropsychological/social cognition tasks are the best approach for characterizing this disease. Although preliminary, our results suggest that social cognition tasks are robust markers of schizophrenia family impairments, and that combining clinical, social and neuropsychological measures is the best approach to asses patients and relatives vulnerability.     

Mortality of geriatric and younger patients with schizophrenia in the community

Little is known about the differences in mortality among non-institutionalized geriatric and younger patients with schizophrenia. In this study long-term mortality and suicidal behavior of all the geriatric (age > or = 65 years), middle-age (age 41-64 years), and young (age 15-40 years) subjects with schizophrenia living in a Chinese rural community were compared. A 10 year follow-up investigation among a 1994 cohort (n = 510) of patients with schizophrenia was conducted in Xinjin County, Chengdu, China. Compared with young subjects, geriatric subjects with schizophrenia were more likely to be female, have more previous physical illness, never accepted treatment, and practice religious (p < or = 0.01). There were no significant differences of suicide attempts among the three groups. Young subjects had a higher rate of suicide (1,033.8 per 100,000 person-years), and geriatric subjects had a higher rate of deaths due to other causes (accident and natural causes) (4,314.2 per 100,000 person-years). Standardized mortality ratios for both suicide and deaths due to other causes were highest in young subjects and the lowest in geriatric subjects. Patients with schizophrenia in all age groups had a marked increase in mortality and suicide. Specific intervention strategies for decreasing mortality and suicide should be developed for patients with schizophrenia in different age groups.     

The Draw-A-Person Test and Process-Reactive Schizophrenia

The Draw-A-Pcrson test was administered to three matched groups of 32 male Ss each: reactive schizophrenics, process schizophrenics, and normal control subjects. Patients were rated for prognosis using the Premorbid Subscale of the Phillips Scale. Drawings were rated by two judges on 80 diagnostic signs culled from the literature. No signs were found to significantly differentiate reactive and process schizophrenics, and only three signs significantly differentiated normals from schizophrenics. It was concluded that a sign approach to the DAP is insensitive to the reaction-process dimension of schizophrenia, and of only limited value in differentiating between normals and schizophrenics in general.     

Cannabis intoxication: effects of monetary incentive on performance, a controlled investigation of behavioural tolerance in moderate users of cannabis.

The study examined the effect of monetary incentive on the performance of five tasks after two heterogeneous groups of experienced users of cannabis and previously naive subjects had smoked placebo material and two dose levels of cannabis. The performance of the motivated subjects was compared with that of two non-motivated matched groups. Dose-related impairment was found on four of the five tasks, supporting previous findings of cannabis-induced impairment of short-term memory, goal-directed behavior and choice reaction times. Results for three of the tasks suggested that the performance of the motivated subjects was less affected by the drug than was the performance of the non-motivated subjects. There was no difference between the performance of subjects naive and experienced with respect to drug use.     

Linguistic abilities in patients with prefrontal damage

The language abilities of 21 patients with prefrontal lesions (11 right and 10 left) and 15 matched normal subjects were analyzed, using a linguistic ability test designed to evaluate performance in six areas: automatic language, language production, verbal memory, syntax, derivative words, and comprehension of logical grammatical structures. Significant differences in the obtained scores of all groups were found. In spite of formal conservation of language in patients with frontal damage, their complex and conceptual verbal abilities were severely compromised.     

TETRAD: Discovering Causal Structure

We describe multilevel modeling of cognitive function in subjects with schizophrenia, their healthy first degree relatives and controls. The purpose of the study was to compare mean cognitive performance between the three groups after adjusting for various covariates, as well as to investigate differences in the variances. Multilevel models were required because subjects were nested within families and some of the measures were repeated several times on the same subject. The following four methodological issues that arose during the analysis of the data are discussed. First, when the random effects distribution was not normal, non-parametric maximum likelihood (NPML) was employed, leading to a different conclusion than the conventional multilevel model regarding one of the main study hypotheses. Second, the between-subject (within-family) variance was allowed to differ between the three groups. This corresponded to the variance at level 1 or level 2 depending on whether repeated measures were analyzed. Third, a positively skewed response was analyzed using a number of different generalized linear mixed models. Finally, penalized quasilikelihood (PQL) estimates for a binomial response were compared with estimates obtained using Gaussian quadrature. A small simulation study was carried out to assess the accuracy of the latter.