Background: Several lines of evidence suggest hippocampal dysfunction in major depression, but the prevalence and nature of specific dysfunctions during the long-term course of major depression is yet to be assessed. A 3D virtual environment navigation task and measurements of hippocampal volume were assessed in remitted former inpatients with moderate to severe depression after an 8 year follow-up period to evaluate whether functional and structural differences existed in the hippocampus beyond depression.
Methods: Performance on a right hippocampus-dependent 3D virtual reality navigation task, memory tests and right and left hippocampal volumes were assessed in 31 remitted depressed (unipolar) patients and 37 healthy subjects.
Results: Remitted depressed patients did not differ significantly from healthy subjects in terms of either neuropsychological performance or hippocampal volume.
Limitations: The sample consisted of remitted inpatients that had been treated with psychotropic drugs during the 8-year follow-up period. Moreover, 11 of the 42 patients included in the original study were excluded from the follow-up study due to persisting depressive illness and suicide.
Conclusions: The study of visuospatial navigation ability and hippocampal volume in remitted depressed patients offers a specific way of assessing dysfunction in the hippocampus in major depression. Our findings do not support the notion that hippocampal impairment of visuospatial function exists beyond the depressive state, thus indicating that hippocampus-related cognitive dysfunction and previously reported reduced hippocampal volume might represent a state and not a permanent trait of the illness. Moreover, our study suggests that intensive drug treatment of the depressive episodes might prevent the deterioration of the hippocampus.
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