Hippocampal volume asymmetry and age at illness onset in males with schizophrenia.

To determine whether there are disturbances of hippocampal volume asymmetry in schizophrenic patients, we obtained contiguous, 1-mm-thick magnetic resonance images in 28 males with chronic schizophrenia and in 28 age-matched healthy males. The schizophrenic patients showed a bilateral reduction in volume of the hippocampal formation (HF; left 7.0%; right 8.7%). This reduction was significantly associated with the severity of disorganization syndrome (P < 0.0005). A significant asymmetry in the HF volume was found in the control subjects (P = 0.006), but not in the patients (P = 0.40). There was a significant positive correlation between the asymmetry index and the patient's age at the onset of schizophrenia (r = 0.46, P = 0.01). Results indicate that a disturbance in the normal asymmetry of the HF may be a characteristic in schizophrenia, particularly in patients with an early onset of the illness.