Hippocampal volume in first-episode psychoses and chronic schizophrenia - A high-resolution magnetic resonance imaging study

Background: It has been proposed that the hippocampus is a potential site f or a neurodevelopmental lesion in schizophrenia. While smaller hippocampal volumes have been described in chronic schizophrenia, there have been few m agnetic resonance imaging studies in first-episode psychosis. Furthermore, no studies have examined the specificity of this finding to first-episode s chizophrenia, compared with first-episode affective psychosis. Methods: Hippocampal and whole-brain volumes were estimated using high-reso lution magnetic resonance imaging in 140 controls, 46 patients with chronic schizophrenia, and 32 patients with first-episode psychosis. Results: Patients with chronic schizophrenia and first-episode psychosis ha d significantly smaller hippocampal volumes as compared with controls. With in the first-episode group, both patients with schizophrenia/schizophrenifo rm psychosis and those with affective psychosis had smaller left hippocampa l volumes as compared with controls. Smaller right hippocampal volumes were associated with age and illness duration in patients with chronic schizoph renia. Hippocampal volumes were not correlated with age of illness onset or medication dosage in either patient group. Conclusions: These data show that smaller hippocam pal volumes are present from the onset of illness. While these findings would support the neurodeve lopmental model of schizophrenia, the finding of smaller left hippocampal v olume in patients with first-episode schizophrenia and affective psychosis does not support the prediction that smaller hippocampi are specific to sch izophrenia. The association of smaller right hippocampal volumes with incre ased illness duration in chronic schizophrenia suggests either that there i s further neurodegeneration after illness onset or that bilateral small hip pocampi predict chronicity.