Reduction in hippocampal formation volume is caused mainly by its shortening in chronic schizophrenia: assessment by MRI.

We performed contiguous, 1 mm thick, magnetic resonance imaging scans in 18 men with chronic schizophrenia and in 18 age-matched healthy subjects to test in living patients the findings of a previous postmortem study. The schizophrenic patients showed bilaterally shortening (left, -6%; right, -9%) and volume reduction (left, -9%; right, -11%) of the hippocampal formation (HF). Volumes of HF correlated positively with HF length in the schizophrenic patients. The reduction in bilateral HF volumes was small after controlling for HF lengths (left, -3%; right, -3%). In schizophrenic patients, significant negative correlations were found bilaterally between the length of HFs and the scores for attention, bizarre behavior, and positive formal thought disorder. The results suggest that the volume reduction seen in the HFs of schizophrenic patients was caused mainly by a shortening of the HF and that these clinical symptoms may be associated with shorter HF length.