Stand der Ursachen - Mitteldeutsche Psychiatrietage 2011

Poster | Affektive Störungen
P24
Altered structural corticosubcortical connectivity in major depression dependent on
symptom severity
A. Osoba, J. Haenggi, D. Horn, J. Kaufmann, U. Eckert, K. Zierhut, K. Schiltz, J. Steiner, B. Bogerts,
M. Walter, Magdeburg
Introduction: Diffusion Tensor Imaging (DTI) can be used to study white matter fiber tracts by measuring
the movement of water molecules (Behrens et al.2003, Mukherjee et al.2008).
It is known that Major Depressive Disorder (MDD) is associated with microstructural brain abnormalities
and changes in white matter (Kieseppä et al.2009, Li et al.2007).
Recent studies could show differences in functional connectivity in the hippocampus, amygdala, dACC and
prefrontal cortex between MDD patients and healthy controls (Greicius et al.2007).
The aim of this study was to find anatomical correlates of the functional differences found in fMRI and the
differences in functional connectivity in MDD patients.
We presumed that a decrease in fractional anisotropy (FA), as a sign of disintegration of white matter tracks
can be found in MDD patients located in cortical and subcortical regions playing an important role in
affective states and behaviors.
Methods: DTI datasets of 20 patients with a major depressive disorder (MDD) and 20 healthy controls were
analysed.
Diffusion Tensor Imaging was performed on a 3 Tesla GE scanner using the following parameters:
TR=8200ms, TE=89ms, FOV=256mm in width and height and a slice thickness of 2 mm.
Diffusion was measured in 12 directories.
Cortical and subcortical regions of interest representing areas found as affected in depression were defined
according to functional MRI studies during task and rest on individual brains.
The FA values within these ROIs as well as their interconnecting fibertracts were tested for differences
between depressive patients and healthy controls.
Data analysis was performed using FSL, SPM5 and SPM8.
Depression severity was ascertained by using the Hamiton Depression Rating Scale (HDRS) and the
Montgomery-Asberg Depression Rating Scale (MADRS).
Results: Comparing MDD patients and healthy controls we found decreased FA values in depressive
patients not only on whole brain level but also in those regions showing functional differences under taskcondition
namely the dACC, corpus callosum and the pgACC. Specific effects of group were further found
for fiber tracts connecting these cortical and the subcortical target regions:
Significant decreases of the FA values in MDD patients were measured in one of these white matter ROIs
namely between the centromedian nucleus of the thalamus and the left amygdala.
In addition severely depressed patients with higher scores in the MADRS show significantly lower FA
values in different white matter ROIs.
Correlations between HDRS and FA values underline the role of depression severity in structural brain
abnormalities.
Moreover we are interested in correlations between cortical thickness and fractional anisotropy and
functional connectivity and structural changes in white matter.
We will present first results.
Conclusion: Our study shows that white matter integrity is reduced in MDD patients on whole brain level,
reflecting a reduced integrity especially in those regions also showing functional differences under taskcondition.
For the first time we could reveal thalamocortical projections involving those regions show a
significant reduction in fractional anisotropy in MDD population compared with healthy controls, when
anatomically defined thalamic subregions with known differential projections to the cortical target regions
are chosen.
Our results suggest anatomical correlates for functional deficits in emotional and cognitive processing in
depressed patients and contribute to a complex understanding of thalamo-cortical circuits in depression.
These anatomical differences provide a new pattern to characterize patients with major depressive disorder
and might be used for diagnostic and therapeutical classification. So we provide a further evidence, that
inter-individual differences in functional MRI reflect anatomical variability.
References:
Behrens, T.E.J. (2003), ‘Non-invasive mapping of connections between human thalamus and cortex using
diffusion imaging’, Nature Neuroscience, vol.6, no.7, pp. 750-757
Greicius, M. (2007), ‘Resting-State Functional Connectivity in Major Depression: Abnormally Increased
Contributions from Subgenual Cingulate Cortex and Thalamus’, Biol Psychiatry, no.62, no.5, pp. 429–437
Kieseppä, T. (2009), ‘Major depressive disorder and white matter abnormalities: A diffusion
tensor imaging study with tract-based spatial statistics’, Journal of Affective Disorders, vol. 120, no.1-3, pp.
240-244
Li, L. (2007), ‘Prefrontal white matter abnormalities in young adult with major depressive disorder: A
diffusion tensor imaging study’, Brain Research, vol.1168, pp.124-128
8. Mitteldeutsche Psychiatrietage | 86