Abstract
Background. Reduced hippocampal volume has been associated with clinical depression. However, it remains unclear whether these changes are a biological vulnerability marker or a consequence of this disorder.
Methods & Results (Study 1). We first compared hippocampal volumes between (i) never-depressed individuals with elevated risk for depression by virtue of high neuroticism (ii) recovered depressed individuals with matched levels of neuroticism; and (iii) individuals with low neuroticism and no history of depression. We replicated the finding of reduced hippocampal volume in the recovered group; unexpectedly however, the never-depressed high-risk group showed an increase in volume. One hypothesis is that this group had a mean age above the typical onset age for depression; hence, these participants who have remained euthymic despite their personality risk might in fact possess some resilience.
Methods & Results (Study 2). A subsequent study was therefore carried out to compare hippocampal volume between high-neurotic vs. low-neurotic volunteers in a younger sample. No group difference was found.
Limitations. The present findings are limited by a small sample size; the cross-sectional design precluded us from making definitive conclusions about causal effect.
Conclusion. Our overall results suggest that reduced hippocampal volumes is a neural marker for the scar effect of depression, although this structural impairment could also be seen as a vulnerability marker for the development of future recurrent episodes. By contrast, larger hippocampal volumes could be a biological marker of resilience. These findings have clinical implications regarding treatment development for the prevention of illness onset and recurrent depressive episodes.
Methods & Results (Study 1). We first compared hippocampal volumes between (i) never-depressed individuals with elevated risk for depression by virtue of high neuroticism (ii) recovered depressed individuals with matched levels of neuroticism; and (iii) individuals with low neuroticism and no history of depression. We replicated the finding of reduced hippocampal volume in the recovered group; unexpectedly however, the never-depressed high-risk group showed an increase in volume. One hypothesis is that this group had a mean age above the typical onset age for depression; hence, these participants who have remained euthymic despite their personality risk might in fact possess some resilience.
Methods & Results (Study 2). A subsequent study was therefore carried out to compare hippocampal volume between high-neurotic vs. low-neurotic volunteers in a younger sample. No group difference was found.
Limitations. The present findings are limited by a small sample size; the cross-sectional design precluded us from making definitive conclusions about causal effect.
Conclusion. Our overall results suggest that reduced hippocampal volumes is a neural marker for the scar effect of depression, although this structural impairment could also be seen as a vulnerability marker for the development of future recurrent episodes. By contrast, larger hippocampal volumes could be a biological marker of resilience. These findings have clinical implications regarding treatment development for the prevention of illness onset and recurrent depressive episodes.
Original language | English |
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Pages (from-to) | 199-202 |
Journal | Journal of Affective Disorders (JAD) |
Volume | 189 |
Early online date | 1 Oct 2015 |
DOIs | |
Publication status | Published - 1 Jan 2016 |
Keywords / Materials (for Non-textual outputs)
- hippocampus
- resilience
- vulnerability
- depression
- risk
- neuroticism