Unit IV(2)

Response Paper

Physiological Functioning, Chemotherapy, and Schizophrenia

Physiological Functioning, Chemotherapy, and Schizophrenia

Many observations have supported the general idea of impaired frontal function in schizophrenia. In particular neuropsychological studies have shown severe frontal deficits. However, other studies found normal cognitive function in a proportion of patients. Since saccadic tasks also provide an index of frontal function, we examined the presence of frontal deficits in patients by means of both neuropsychological and saccadic tasks, and compared the sensitivity of both approaches for frontal impairment. Schizophrenia is a severe psychiatric disease, characterized by a range of dysfunctions in perception, thinking, language, behavior, affect, volition, drive and cognition. No single symptom is pathognomonic for the disease. Psychotic episodes with delusions, hallucinations and often bizarre behavior, combined with disorganized speech and thinking are often alternated with periods in which negative symptoms, such as loss of initiative, flattening of affect and psychomotor poverty are prominent.

Many observations have supported the general idea of impaired frontal function in schizophrenia. In particular neuropsychological studies have shown severe frontal deficits. However, other studies found normal cognitive function in a proportion of patients. Since saccadic tasks also provide an index of frontal function, we examined the presence of frontal deficits in patients by means of both neuropsychological and saccadic tasks, and compared the sensitivity of both approaches for frontal impairment. Many observations have supported the general idea of impaired frontal function in schizophrenia. In particular, studies addressing frontal functions by means of neuropsychological (NP) tests have demonstrated severe cognitive deficits. It has, therefore, been proposed that frontal cognitive deficits are among the core deficits of schizophrenia (Goldman-Rakic 1994; Hemsley 1994).

However, this assumption is not in accordance with studies that found a substantial proportion of patients with normal NP performance, including performance on frontal tasks (Silverstein & Zerwic 1985; Bryson et al. 1993; Palmer et al. 1997; Holthausen et al. 2002). Estimates of this proportion vary from 19% (Holthausen et al. 2002) (Bryson et al. 1993). Mortality is high, with a suicide rate of 10 percent. The illness usually reaches a stable level after the first two to five years (Belitsky and McGlashan, 1993). The course of illness in the early phase of the disease is a good predictor for the long-term course (Harrison et al., 1996). Other known factors associated with a good prognosis are good premorbid adjustment, acute onset, later age at onset, being female, precipitating events, associated mood disturbance and no family history of schizophrenia. In order to determine if frontal impairment is a core deficit of schizophrenia, it seems worth the effort to evaluate frontal functions by means of an alternative method, namely the recording of saccadic eye movements. Saccades are fast eye movements, which are made to fixate objects on the fovea. These eye movements can be easily implemented in various cognitive tasks. An advantage of such tasks is that the neural systems subserving these tasks are well known from primate studies (Bruce & Goldberg 1985; Hikosaka & Wurtz 1991; Everling et ...