Background. We have used proton magnetic resonance imaging and spectroscopy to measure
hippocampus/amygdala volumes and anterior hippocampal metabolite concentrations (N-acetyl
aspartate (NAA), creatine/phosphocreatine and choline) in subjects with temporal lobe epilepsy
(TLE), schizophrenia and in normal controls.
Method. Four groups of right-handed patients were selected: 12 with TLE and psychosis (EP), 12
with TLE and no psychosis (ENP), 26 with schizophrenia, and 38 normal controls. Imaging and
spectroscopy were performed with a 1.5T Signa GE scanner.
Results. The schizophrenia group showed a significant left-sided reduction in all metabolites. In the
epilepsy groups NAA was reduced bilaterally. The NAA reduction in the EP group was greater than
in the ENP group, especially on the left, although the result did not reach significance. Total
hippocampus/amygdala volumes showed no significant differences in any of the groups when
compared with normal controls. When compared with controls significant, specific regional volume
reductions were present bilaterally in the EP group and in the left hippocampus/amygdala in
schizophrenia. The regional volume reduction found in schizophrenia was also present in EP but
not in ENP.
Conclusion. Spectroscopic abnormalities were more pronounced in the epilepsy groups and were
bilateral, and abnormalities in schizophrenia were left sided. Specific regional hippocampus/amygdala
volume reductions were more marked in the EP group and were bilateral. Left-sided
regional volume reduction identified in the dominant hemisphere of schizophrenics was also present
in EP patients, but not in ENP, suggesting that this region in the left temporal lobe may be
significant in the aetiology of psychosis. This is further supported by the predominantly left-sided
NAA reduction in schizophrenia. High resolution morphometric studies may identify specific
regions of the brain associated with the development of psychosis.