We have used proton magnetic resonance spectroscopy to study in vivo N-acetyl aspartate (NAA), choline and creatine in the hippocampi of 26 schizophrenics and 38 normal controls. Measurements of NAA suggest that age-related neuronal loss occurs at a similar rate in schizophrenics and controls. On the other hand, we observe in schizophrenics age-related choline abnormalities not present in controls. We suggest that these age-related changes may be related to an abnormal myelination process and contribute to the observed clinical deterioration associated with schizophrenia.