Continuous performance tests in schizophrenic patients: stimulus and medication effects on performance.

Medicated (n = 17) and unmedicated (n = 17) schizophrenic patients were compared to a normal control group (n = 19) on their performance on auditory and visual versions of the Continuous Performance Test (CPT). Within each stimulus modality, performance was examined on lexical and nonlexical target stimuli. Neuromotor competence was assessed on the basis of motor speed and proficiency. Normal subjects made fewer errors of all types than schizophrenic patients. Unmedicated patients made significantly more errors on nonlexical stimuli than medicated patients, with medication status found not to be associated with stimulus modality effects. Motor proficiency was associated with CPT performance in the medicated patients, but not the unmedicated ones, although this difference in correlations did not account for the group differences between these patients. The authors discuss the implications of these data for the type of cognitive and attentional functions that are affected by medication in schizophrenia.

Cognitive deficits and thought disorder: a retest study.

Manic (n = 26), schizophrenic (n = 26), and normal (n = 25) subjects were examined with a digit span distraction task and with a reality monitoring task. All subjects were tested twice at a 4-day interval, and a clinical assessment of thought disorder was conducted both times on the patients. We found that reality monitoring, distraction task performance, and clinical thought disorder were all quite stable at the retest interval. We further found that different patterns of correlational relationships between cognitive deficits and positive and negative thought disorders were present in the manic and schizophrenic samples. When we conducted a cross-temporal analysis of our data, we found that no cognitive deficits in mania predicted the severity of positive thought disorder over time, although the severity of thought disorder predicted distraction performance over time. In the schizophrenic subjects, distraction performance, but not reality monitoring, exerted a significant cross-temporal influence on positive thought disorder.

The consistency of thought disorder in mania and schizophrenia. II. An assessment at consecutive admissions.

Manic (N = 8) and schizophrenic (N = 14) acute admissions were assessed 10 days after they arrived at the hospital. These assessments were conducted on two consecutive acute admissions for each patient. Interview-based clinical ratings were collected and examined for the stability of both positive and negative thought disorders. For schizophrenics, negative thought disorder, particularly poverty of speech, was relatively consistent across admissions. In the manic sample, much less consistency was observed. The results are evaluated in terms of the statements that they make regarding the validity of the thought disorder construct and for their implications regarding causal factors in communication disorders.

Distractibility and discourse failure. Their association in mania and schizophrenia.

Manic (N = 18) and schizophrenic (N = 23) patients were evaluated with a linguistic assessment of reference failures and were tested with a digit span distraction task. It was found that, although manics and schizophrenics did not differ in their distraction performance, there were differential relationships between task performance and reference performance across the two subject samples. Both distraction and nondistraction performances were related equally to discourse failures in manics while distraction performance was a much better predictor of discourse failure than nondistraction performance in the schizophrenic sample. The fact that susceptibility to the effects of distraction seemed to be an important and specific predictor of discourse failures in schizophrenia is discussed in terms of recent developments in research and theory regarding schizophrenic speech disorders.

Encoding, memory, and thought disorder in schizophrenia and mania.

Schizophrenic (n = 24) and manic (n = 20) inpatients were compared with a normal comparison sample (n = 10) on memory and encoding performance for both self- and other-generated speech. It was found that the level of encoding, as indexed by the level of organization present in the recalled speech, predicted memory performance for both schizophrenic and normal samples. Schizophrenics were less effective at encoding than normals, although the relationship between level of encoding and memory performance was similar for both samples. For the manic patients, however, clinically rated thought disorder predicted memory performance better than encoding performance. It appeared that thought disorder specifically disrupted recall performance, with less of an effect on encoding. These relationships, as well as the lack of a significant relationship between thought disorder and task performance in the schizophrenics, are discussed in terms of their implications for later research in the area of information processing in psychotic patients.

The consistency of thought disorder in mania and schizophrenia. An assessment of acute psychotics.

This report presents an assessment of 20 manic and 20 schizophrenic patients using a clinical rating instrument: the Scale for Assessment of Thought, Language, and Communication (TLC). These 40 patients were assessed three times within a 10-day period at the outset of an acute psychotic episode with open-ended interviews which were then evaluated with the TLC. It was found that clinically rated speech disorders were relatively consistent within these patients at the outset of a psychotic episode. Furthermore, it was found that composite ratings of positive and negative speech disorders, as defined by the TLC, were stable discriminators of the manic and schizophrenic patients, while global thought disorder was not useful as a discriminator. The results provide evidence that thought disorder in psychosis may be a stable trait of patients during acute episodes and that positive and negative disorder is a useful construct.