Schizophrenia is the most severe mental illnesses
characterized by delusions hallucinations,
disorganized speech of frequent derailment or
incoherence and grossly disorganized behaviour.
The deficient processes involved in this disorder are
clinically silent until the onset of prodromal or psychotic
symptoms, at which time neuropsychological testing
demonstrates the presence of cognitive deficits that are
often chronic and apparently irreversible (Goldberg et
al.,1993). The clinical picture of schizophrenia has led
many authors to speculate that particularly the negative
features of schizophrenia reflect deficits in executive
functioning (Anderesen et al., 1989).