Hippocampal Plasticity in Response to Exercise in Schizophrenia

Abstract

Hippocampal volume is lower than expected in patients with schizophrenia; however, whether this represents a fixed deficit is uncertain. Exercise is a stimulus to hippocampal plasticity. To determine whether hippocampal volume would increase with exercise in humans and whether this effect would be related to improved aerobic fitness. Randomized controlled study. Patients attending a day hospital program or an outpatient clinic. Male patients with chronic schizophrenia and matched healthy subjects. Aerobic exercise training (cycling) and playing table football (control group) for a period of 3 months. Magnetic resonance imaging of the hippocampus. Secondary outcome measures were magnetic resonance spectroscopy, neuropsychological (Rey Auditory Verbal Learning Test, Corsi block-tapping test), and clinical (Positive and Negative Syndrome Scale) features. Following exercise training, relative hippocampal volume increased significantly in patients (12%) and healthy subjects (16%), with no change in the nonexercise group of patients (-1%). Changes in hippocampal volume in the exercise group were correlated with improvements in aerobic fitness measured by change in maximum oxygen consumption (r = 0.71; P = .003). In the schizophrenia exercise group (but not the controls), change in hippocampal volume was associated with a 35% increase in the N-acetylaspartate to creatine ratio in the hippocampus. Finally, improvement in test scores for short-term memory in the combined exercise and nonexercise schizophrenia group was correlated with change in hippocampal volume (r = 0.51; P < .05). These results indicate that in both healthy subjects and patients with schizophrenia hippocampal volume is plastic in response to aerobic exercise.