Temporal lobe epilepsy with and without psychosis: exploration of hippocampal pathology including that in subpopulations of neurons defined by their content of immunoreactive calcium-binding proteins

We have investigated relationships between hippocampal/temporal lobe neurop athology and psychosis in subjects with temporal lobe epilepsy, paying part icular attention to possible differences in density of hippocampal neurons immunoreactive for calcium-binding proteins. There was a trend for a greate r prevalence of left handedness in the psychotic (n = 6) than the non-psych otic (n = 26) cases (P = 0.0504). Psychotic cases also differed from non-ps ychotic ones in having: (1) more focal lesions outside the hippocampus (P = 0.006); (2) less severe CA1 neuron loss (P = 0.015); and (3) a trend, afte r Bonferroni correction, for a higher density of calbindin-immunoreactive n eurons in the CA4 (P = 0.022). An additional finding was that dentate granu le cell dispersion was significantly associated with the presence of a redu ced density of calretinin-immunoreactive neurons in CA4 (P = 0.002) and wit h a more severe loss of CA4 neurons visible with Nissl stain (P = 0.003). T hus, cases of temporal lobe epilepsy with psychosis were distinguishable on the basis of a higher density of calbindin-reactive neurons in CA4 as well as on more general aspects of their pathology.