Hippocampal morphology in lithium and non-lithium-treated bipolar I disorder patients, non-bipolar co-twins, and control twins

Background: Bipolar I disorder is a highly heritable psychiatric illness with undetermined predisposing genetic and environmental risk factors. We examined familial contributions to hippocampal morphology in bipolar disorder, using a population‐based twin cohort design. Methods: We acquired high‐res...

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Bibliographic Details
Published in:Human brain mapping 2012-03, Vol.33 (3), p.501-510
Main Authors: van Erp, Theo G.M., Thompson, Paul M., Kieseppä, Tuula, Bearden, Carrie E., Marino, Alexandria C., Hoftman, Gil D., Haukka, Jari, Partonen, Timo, Huttunen, Matti, Kaprio, Jaakko, Lönnqvist, Jouko, Poutanen, Veli-Pekka, Toga, Arthur W., Cannon, Tyrone D.
Format: Article
Language:English
Subjects:
Adult
Antimanic Agents - therapeutic use
Biological and medical sciences
bipolar disorder
Bipolar Disorder - drug therapy
Bipolar Disorder - pathology
Female
Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy
hippocampus
Hippocampus - drug effects
Hippocampus - pathology
Humans
Image Interpretation, Computer-Assisted
Imaging, Three-Dimensional
Investigative techniques, diagnostic techniques (general aspects)
Lithium Compounds - therapeutic use
Magnetic Resonance Imaging
Male
Medical sciences
Middle Aged
mood disorders
morphology
Nervous system
Nervous system (semeiology, syndromes)
Neurology
Radiodiagnosis. Nmr imagery. Nmr spectrometry
shape
twin
volume
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Summary:Background: Bipolar I disorder is a highly heritable psychiatric illness with undetermined predisposing genetic and environmental risk factors. We examined familial contributions to hippocampal morphology in bipolar disorder, using a population‐based twin cohort design. Methods: We acquired high‐resolution brain MRI scans from 18 adult patients with bipolar I disorder [BPI; mean age 45.6 ± 8.69 (SD); 10 lithium‐treated], 14 non‐bipolar co‐twins, and 32 demographically matched healthy comparison twins. We used three‐dimensional radial distance mapping techniques to visualize hippocampal shape differences between groups. Results: Lithium‐treated BPI patients had significantly larger global hippocampal volume compared to both healthy controls (9%) and non‐bipolar co‐twins (12%), and trend‐level larger volumes relative to non‐lithium‐treated BPI patients (8%). In contrast, hippocampal volumes in non‐lithium‐treated BPI patients did not differ from those of non‐bipolar co‐twins and control twins. 3D surface maps revealed thicker hippocampi in lithium‐treated BPI probands compared with control twins across the entire anterior‐to‐posterior extent of the cornu ammonis (CA1 and 2) regions, and the anterior part of the subiculum. Unexpectedly, co‐twins also showed significantly thicker hippocampi compared with control twins in regions that partially overlapped those showing effects in the lithium treated BPI probands. Conclusions: These findings suggest that regionally thickened hippocampi in bipolar I disorder may be partly due to familial factors and partly due to lithium‐induced neurotrophy, neurogenesis, or neuroprotection. Unlike schizophrenia, hippocampal alterations in co‐twins of bipolar I disorder probands are likely to manifest as subtle volume excess rather than deficit, perhaps indicating protective rather than risk effects. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
ISSN:1065-9471
1097-0193
DOI:10.1002/hbm.21239