Searching the schizophrenic brain for temporal lobe deficits: a systematicreview and meta-analysis

Background. Several empirical studies have found temporal lobe impairments in many patients with schizophrenia. The strength and consistency of this e vidence, however, has not been evaluated and synthesized quantitatively. He nce, we ask to what extent are temporal cortices really defective in schizo phrenia? Methods. Meta-analytical methods were used to determine the magnitude of ev idence in support of structural and physiological temporal-hippocampal syst em deficits in schizophrenia. We report effect sizes from studies since 198 0 that used structural (CT, MRI) and functional (SPECT, PET) neuroimaging m ethods. Results. Both structural and functional imaging literatures are distinguish ed by heterogeneity whereby most patients show normative temporal function and structure, a minority shows diminished values and some patients demonst rate augmented function and structure rather than a deficit. Conclusions. The findings are hard to incorporate within single disease mod els that propose major involvement of the temporal system in schizophrenia, at least at the degree of resolution obtained with current imaging technol ogy.