Background. The schizophrenia-like psychoses of epilepsy (SLPE) might represent a secondary
form of schizophrenia in which the pathology is relatively confined to the temporal lobe. To test this
possibility we have compared the neuropsychological profile of schizophrenia and SLPE. Our main
hypothesis was that both psychotic groups would show deficits of temporal lobe function but that
prefrontal impairment, as measured by tests of executive function, would be found only in the
primary schizophrenic group.
Methods. Four groups were studied: (1) patients with SLPE (N = 25); (2) patients with epilepsy but
not psychiatric history (N = 24); (3) patients with schizophrenia (N = 22); and (4) healthy
volunteers (N = 24). Neuropsychological testing comprised measures of pre-morbid IQ, current
verbal and performance IQ, information processing, digit span, motor speed, verbal and visual
learning and memory, verbal fluency, the Wisconsin Card Sorting Task, the Stroop test and the trail
Results. Patients with schizophrenia and those with SLPE had almost identical neuropsychological
profiles, with impairments of attention, episodic memory (verbal > visual) and executive function.
The epileptic controls showed similar though less severe impairments of memory and of some tests
of executive function.
Conclusions. Our results do not support the hypothesis that the pathophysiology of SLPE and
schizophrenia are distinct. While our findings suggest an important role for dominant temporal lobe
abnormality in schizophrenia, both in its primary form and in that occurring in patients with
epilepsy, they also implicate generalized cognitive impairment, manifest in particular as attentional
deficits, in both forms of the disorder.