Dysfunction of the anterior hippocampus: The cause of fundamental schizophrenic symptoms?

Recent evidence suggests there is an association between schizophrenia and dysfunction of the anterior hippocampus. Accordingly, this paper endeavors to show how the fundamental schizophrenic symptoms described by Bleuler might arise from deficiencies in normal hippocampal function. This effort is based on the idea that the hippocampus normally constructs a composite picture or worldview of the environment when conditions are novel or uncertain. Then when conditions become familiar, it influences emotion and behavior to be consistent with that worldview. The anterior hippocampus maintains the emotional component of a worldview through its interaction with the amygdala and hypothalamus, and supports executive frontal lobe activity by way of its output to the nucleus accumbens. From this perspective, the split between affect and cognition in schizophrenia is attributed to a failure of the anterior hippocampus to enforce the emotional component of a worldview allowing emotions to diverge from the cognitive component. The splitting of associations is traced to a failure of anterior hippocampal output to support frontal lobe control over the flow of associations. And a split from reality is seen to arise from a combination of these two failures. The individual ceases to interact with the world because the lack of executive control makes such interaction difficult. Fear and fantasies come to dominate experience because emotions are not adequately controlled. (c) 2005 Elsevier Ltd. All rights reserved.