In this article, we review attempts to account for the thought disorder present in some schizophrenic patients in terms of cognitive deficits in the domains of working memory, attention, language, and semantic memory. Although each psychological construct can account for some of the data described here, establishment of a primary cognitive impairment responsible for thought disorder is not forthcoming, perhaps due to its underlying multidimensional pathology. While the relationship of working memory, attention, and language processing to thought disorder is ambiguous, semantic memory is emerging as a promising construct, that may yield insight into cognitive mechanisms that underlie thought disorder and neuroleptic responsiveness.

In this article, we present data on the analysis of maze-solving behavior as a tool for the investigation of cognitive disturbance in schizophrenic patients. Solving maze tasks efficiently requires both an interaction between and an integration of perceptive and action-oriented processes. Starting from the hypothesis that these domains are preferentially disturbed in schizophrenia, we propose that the maze-solving behavior of schizophrenic patients permits insight into specific impairments in disease-related cognitive processing. We present the results of a maze task study comparing medication-free schizophrenic patients and matched healthy controls. This analysis forms the basis for an investigation of the influence of psychopharmacological treatment strategies on the observed behavior in the maze-solving paradigm. Finally, a third study concerned with improvement over time associated with medication is presented, and possible influences of extrapyramidal motor disturbances on schizophrenic patients' maze performance are discussed.

Cognitive impairment is considered a central feature of schizophrenia. Many aspects of cognition are impaired in schizophrenia. Careful evaluation of the relationship between cognitive impairment and the other symptoms of schizophrenia has revealed several important findings. In this article, we discuss these findings, the effects of typical neuroleptic therapy on cognitive impairment, and important issues to address in cognitive enhancement studies in schizophrenia.

Past research has established that traditional neuroleptic treatment improves attentional functioning in schizophrenic (SZ) patients. The present investigation expands on this finding by examining attentional improvement in nine acute SZ patients treated with either the novel neuroleptic ziprasidone or aripiprazole over a 4-week inpatient period. Twelve SZ in patients receiving typical neuroleptic treatment over the same time period served as controls. The results revealed that while all patients showed marked attentional improvement from medication-free baseline to week 4 of treatment, the SZ patients who received novel antipsychotics showed significant improvement on immediate recall and reaction time measures. These results suggest that novel neuroleptic treatment, perhaps through preferential activation of the prefrontal cortical pathways, improves SZ patients' information processing speed and efficiency.

In this article, data are presented from Parts A and B of the Trail Making Test, which examined the effects of haloperidol vs risperidone on cognitive function in treatment-resistant scxhizophrenic patients. This report focuses on findings from the Trail Making Test. Overall, risperidone had a positive effect on Trail Making Part B performance following 4 weeks of treatment. These effects were due, at least in part, to the direct effects of risperidone. The possibility that an antipsychotic agent can enhance executive functioning through direct mechanisms, perhaps mediated by frontal cortex neurochemistry, indicates that the evaluation of antipsychotic medications in the treatment of schizophrenia should be expanded to include cognition.