TY - JOUR

T1 - Hypothalamic-pituitary-adrenal axis tonus is associated with hippocampal microstructural asymmetry

AU - Madsen, Kathrine Skak

AU - Jernigan, Terry L

AU - Iversen, Pernille

AU - Frøkjær, Vibe Gedsø

AU - Knudsen, Gitte Moos

AU - Siebner, Hartwig Roman

AU - Baaré, William F C

N1 - Copyright © 2012 Elsevier Inc. All rights reserved.

PY - 2012/10/15

Y1 - 2012/10/15

N2 - It is well-established that prolonged high levels of cortisol have adverse effects on hippocampal neurons and glial cells. Morphometric studies linking hippocampus volume to basal HPA-axis activity, however, have yielded less consistent results. Asymmetry may also be considered, since there is growing evidence for hemispheric lateralization in brain systems regulating arousal and emotion. Here we tested the hypotheses that individual variations in basal morning and afternoon/evening cortisol levels would be associated with the degree of hemispheric asymmetry in hippocampal microstructure. Fifty healthy adults aged 19 to 86 years were included in the analyses. Diffusion-weighted imaging was acquired from all subjects. Hippocampal mean diffusivity (MD) and volume was extracted. Cortisol measures were based on 5 morning and 3 afternoon/evening saliva samples. Higher left relative to right hippocampus MD was associated with higher basal cortisol levels. Associations were anatomically specific and not attributable to hippocampal volume asymmetry. No correlation between hippocampal volume and MD was observed, suggesting that MD and volume index distinct biological properties of the hippocampus. Observed associations raise a number of possibilities, among them an asymmetric role of the hippocampus on HPA-axis regulation, or conversely, that individual variations in secreted cortisol, perhaps associated with stress, may have lateralized effects on hippocampal microstructure. Our results point to an important relationship between the limbic system and neuroendocrine function in terms of left-right asymmetries, raising additional questions about how the limbic system is related to neuroendocrine functions.

AB - It is well-established that prolonged high levels of cortisol have adverse effects on hippocampal neurons and glial cells. Morphometric studies linking hippocampus volume to basal HPA-axis activity, however, have yielded less consistent results. Asymmetry may also be considered, since there is growing evidence for hemispheric lateralization in brain systems regulating arousal and emotion. Here we tested the hypotheses that individual variations in basal morning and afternoon/evening cortisol levels would be associated with the degree of hemispheric asymmetry in hippocampal microstructure. Fifty healthy adults aged 19 to 86 years were included in the analyses. Diffusion-weighted imaging was acquired from all subjects. Hippocampal mean diffusivity (MD) and volume was extracted. Cortisol measures were based on 5 morning and 3 afternoon/evening saliva samples. Higher left relative to right hippocampus MD was associated with higher basal cortisol levels. Associations were anatomically specific and not attributable to hippocampal volume asymmetry. No correlation between hippocampal volume and MD was observed, suggesting that MD and volume index distinct biological properties of the hippocampus. Observed associations raise a number of possibilities, among them an asymmetric role of the hippocampus on HPA-axis regulation, or conversely, that individual variations in secreted cortisol, perhaps associated with stress, may have lateralized effects on hippocampal microstructure. Our results point to an important relationship between the limbic system and neuroendocrine function in terms of left-right asymmetries, raising additional questions about how the limbic system is related to neuroendocrine functions.

U2 - 10.1016/j.neuroimage.2012.06.071

DO - 10.1016/j.neuroimage.2012.06.071

M3 - Journal article

C2 - 22776454

VL - 63

SP - 95

EP - 103

JO - NeuroImage

JF - NeuroImage

SN - 1053-8119

IS - 1

ER -