Neuroimaging studies of the hippocampus in schizophrenia.

Three neuroimaging techniques, morphometric neuroimaging, magnetic resonance spectroscopy, and functional neuroimaging, have provided evidence for abnormal hippocampal structure and function in schizophrenia. Hippocampal volume reduction is now one of the most consistent structural abnormalities found in schizophrenia: it is present at the onset of the illness and, to a lesser degree, in first-degree relatives of schizophrenic probands. Decreased levels of N-acetyl-aspartate point towards a cellular basis of such volume changes. Functional neuroimaging studies have demonstrated abnormal levels of hippocampal activity at rest, during the experience of auditory hallucinations, and during the performance of memory retrieval tasks. These results of neuroimaging studies complement evidence from post-mortem and behavioral studies, which have found regionally specific abnormalities of the hippocampus and of memory function in schizophrenia.