Douglas C Dean1, Elizabeth M Planalp1,2, William Wooten3, Nagesh Adluru1, H Hill Goldsmith1,2, Andrew L Alexander1,4,5, and Richard J Davidson1,2,3,4
1Waisman Center, University of Wisconsin Madison, Madison, WI, United States, 2Psychology, University of Wisconsin Madison, Madison, WI, United States, 3Center for Healthy Minds, University of Wisconsin Madison, Madison, WI, United States, 4Psychiatry, University of Wisconsin Madison, Madison, WI, United States, 5Medical Physics, University of Wisconsin Madison, Madison, WI, United States
Synopsis
Exposure to differing
concentrations of cortisol likely has a significant impact on brain development
in childhood and adolescence; however, little is known about the time
immediately following birth. Using multi-shell diffusion imaging data, we examined
the associations between prenatal maternal diurnal cortisol patterns and infant
white matter microstructure. Infant measures were associated with the slope of
the maternal cortisol response across white matter, suggesting variations of
cortisol within the intrauterine environment may have a significant influence on processes of
early brain development.
Introduction
The human brain undergoes rapid but
systematic development that results from a cascade of intricate processes governed
by sensitive interactions between genetic and environmental factors1,2.
Increasing evidence suggests that early life experiences play a critical role
in early child development and that genetic and environmental alterations can
have long lasting consequences for fetal and postnatal brain maturation3,4.
One factor that may significantly impact the intrauterine environment and
consequently influence early brain development is exposure to heightened
concentrations of the human stress hormone, cortisol. Cortisol has wide-ranging
metabolic and immune effects5, while also playing a necessary role
in promoting processes of brain development, including neurogenesis,
synaptogenesis, axonal and dendritic arborization, and myelination6,7.
Despite maternal cortisol increasing 3-5-fold over the course pregnancy8,
little is known about how variations of maternal cortisol concentrations or
rhythms impact early brain development. Utilizing salvia samples collected from
mothers during the third trimester of pregnancy and neuroimaging data acquired
in their 1-month old infants, we examined the associations between prenatal
maternal diurnal cortisol rhythms and infant white matter microstructure.
Methods
Mothers were identified and enrolled during the second
trimester of pregnancy. Mothers collected their own saliva and recorded the
collection times in the home three times a day (upon waking, in the afternoon,
and right before bed) for three consecutive days at approximately 35 weeks
gestation. Upon assaying salvia samples, maternal diurnal cortisol curves were estimated
using linear mixed effects models. At one month of age, infants underwent
non-sedated MRI, which included multi-shell diffusion imaging. After standard
processing, including correction of motion and eddy currents and non-parenchyma
tissue removal, data were fit to the diffusion tensor model using RESTORE9
and the neurite orientation dispersion and density imaging (NODDI) model10.
Fractional anisotropy (FA), and mean and radial diffusivity (MD, RD, respectively),
as well as the intra-cellular volume fraction (vIC ) and orientation
dispersion index (ODI) were calculated and aligned to a study-specific template
created using ANTs11. Spatially aligned parameter maps were smoothed
with a 5mm full-width-at-half-maximum kernel. Voxelwise associations between
35-week diurnal slope and infant white matter microstructure (FA, MD, RD, AD, vIC,
and ODI) were assessed using nonparametric permutation testing (randomise12)
with 5000 permutations and threshold-free cluster enhancement13.
Additional nuisance covariates of infant age (corrected to a 40-week
gestation), 35-week diurnal intercept, maternal education level and total
infant motion were included.
Results
Representative cortisol curves for each participating mother are
shown in Fig.1. The intercepts and slopes of these curves vary between
individual mothers, illustrating the significant individual variation of the
cortisol response. We observed highly significant positive associations between
35-week maternal cortisol slopes and DTI/NODDI indices across the brain. In
particular, ODI was positively associated with maternal cortisol slope across
white matter regions (Fig 2) and including regions such as the genu and body of
the corpus callosum, optic radiations and frontal white matter. These
associations indicate smaller amounts of dispersion or fanning in association with
more negative cortisol slopes. Similarly, MD and RD in the corpus callosum
were positively correlated with maternal cortisol slope (Fig 3), while higher vIC
in the superior longitudinal fasciculus, thalamic radiations, parietal
and occipital white matter was associated with higher cortisol slope.
Conclusions
Prenatal maternal cortisol patterns are
associated with alterations to 1-month infant white matter microstructure. In
particular, higher ODI, MD and RD in infants born to mothers whose cortisol
slopes are flatter across the day are consistent
with reductions of microstructural integrity and suggestive of disrupted or
immature white matter development. These results provide
new insights into understanding patterns of white matter
microstructure and add to the growing
consensus that prenatal life experiences have an important role on early brain
development. Future analyses will examine whether these relationships differ in
male and female infants as well as how these early alterations may impact later
childhood development.Acknowledgements
We thank the
participants and their families. We also thank Corrina Frye, Corey Schmidt,
Nicole Schmidt, and Sarah Short for their help. This work was supported by the
National Institutes of Mental (P50 MH100031, RJD, R01 MH101504, HHG, PI, and K99MH110596,
DCD, PI). Infrastructure support was also provided, in part, by a core grant to
the Waisman Center from the National Institute of Child Health and Human
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