Background The association between temporal lobe epilepsy and schizoph
renia suggests that the critical abnormality may be pathology within t
he temporal lobes. People with schizophrenia-like psychosis of epileps
y (SLPE) provide a useful group in which to examine the importance of
temporal and frontal lobe dysfunction in schizophrenia. Method A verba
l fluency activation paradigm and a Te-99m HMPAO SPET were used to stu
dy frontotemporal function in people with SLPE (n=12), schizophrenia (
n=11)and epilepsy (n=16). Results People with SLPE differed from both
other groups by showing lower blood flow in the left superior temporal
gyrus during performance of a verbal fluency task compared with a wor
d repetition task (F=5.4, P=0.0 I). During the verbal fluency task peo
ple with primary schizophrenia showed a greater increase in blood now
in anterior cingulate (F=4.5, P=0.02) than the other two groups.There
were no between-group differences in frontal brain regions. Conclusion
Our findings support an association between left temporal lobe abnorm
ality and SLPE.The different patterns of activation observed in people
with primary schizophrenia and SLPE suggests that different pathophys
iological mechanisms may operate in these two groups. In SLPE the path
ophysiology may be relatively confined to the dominant temporal lobe.