ABSTRACTS - World Psychiatric Association

specifically, these studies have either investigated single fiber tracts
(i.e., using region of interest analysis) or they have relied upon error
prone DTI normalization to the template space (i.e., voxel based morphometry,
VBM analyses). Here the focus is on whole brain analytic
approaches, where existing VBM DTI data analyses are presented as
well as recent methodological advances in studying WM alterations
in schizophrenia. Two new methods of whole brain data analysis,
atlas based segmentation and group based spectral clustering, are
introduced, and results using these new methods are reported from a
dataset that includes 25 chronic schizophrenia subjects and 25
healthy controls. Findings are presented from the two methods and
the implications from these studies are discussed, as well as the
advantages and disadvantages of using these methods vs. more conventional
VBM methods.
RS2.3.
DIFFUSION TENSOR TRACTOGRAPHY
IN FIRST-EPISODE SCHIZOPHRENIA
G. Price, M. Cercignani, G. Parker, D. Altmann, T. Barnes,
G. Barker, E. Joyce, M. Ron
Institute of Neurology, University College, London, UK;
Imperial College Faculty of Medicine, London, UK;
Institute of Psychiatry, King’s College, London, UK; Santa Lucia
Foundation, Rome, Italy; Imaging Science and Biomedical
Engineering, University of Manchester, UK; Medical Statistics
Unit, London School of Hygiene and Tropical Medicine,
London, UK
Disconnectivity abnormalities in the cortex and connecting white
matter pathways may explain the symptoms and cognitive abnormalities
of schizophrenia. Recently, diffusion imaging tractography has
made it possible to study white matter pathways in detail in vivo and
in this paper a corpus callosum study (18 patients and 21 controls)
and an uncinate fasciculus study (19 patients and 23 controls) are presented
for a sample of patients with first-episode schizophrenia using
a probabilistic tractography algorithm. In the study of the corpus callosum,
seed points were placed in the splenium and genu to track fibre
tracts crossing these regions. A multi-threshold approach and multiple
linear regressions were used to explore group differences. Fractional
anisotropy (FA) was reduced in tracts crossing the genu, and to
a lesser degree the splenium, in patients compared with controls. In
the study of the uncinate fasciculus, two seed points were used to isolate
the tract in each hemisphere. FA and probability of connection
were obtained for every voxel in the tract and the group means and
distributions of these variables were compared. The FA distribution,
as measured by the squared coefficient of variance, was reduced in the
left uncinate fasciculus in the patient group, indicating that the number
of voxels with high FA values was reduced, suggesting abnormalities
in the core of the tract. These studies suggest that there are subtle
abnormalities in structural connectivity in patients that may involve
aberrant connectivity in the core of the white matter tract.
RS2.4.
WHITE MATTER VOLUME, ANISOTROPY,
AND TRACT TARGETING QUALITY IN
SCHIZOPHRENIA: FIXED OR PROGRESSIVE
M.S. Buchsbaum, S. Mitelman, E.L. Canfield, J. Schneiderman,
K.-W. Chu, J.J. Entis, E.A. Hazlett, M. Haznedar, I. Nenadic,
J. Zhang, J. Friedman
Mount Sinai School of Medicine Department of Psychiatry,
New York, NY, USA
Several studies have suggested progressive focal gray matter loss in
schizophrenia, but longitudinal white matter changes in anisotropy
have not yet been systematically assessed regionally. Two studies were
conducted: a) diffusion-tensor and structural magnetic resonance
imaging in a cohort of 49 schizophrenia patients and 16 controls
scanned twice 4 years apart; patients were subdivided into good-outcome
(n=23) and poor-outcome; b) 3T-MP-RAGE anatomical and
diffusion tensor images on 111 patients with schizophrenia and 222
normals. Placement of images in standard AC-PC position, coregistration
of DT images to the anatomical images, computation of
anisotropy and tract-angles was done with FSL. White matter and
gray matter volumes and fractional anisotropy were parcellated into
Brodmann areas and entered into multiway ANCOVA. In the followup
sample at baseline, anisotropy was lower in patients and they
showed larger white matter volume. Over four years, anisotropy
declined more in controls bringing normal and schizophrenia levels
closer; controls showed small white matter increases, again bringing
them closer to patient values. For anisotropy and white matter,
patients with good outcome showed a pattern not dissimilar to controls,
but gray matter volume loss continued in poor-outcome
patients. Tract angles changed little over time. In the cross-sectional
sample, lower anisotropy was observed widely in schizophrenia, but
most prominently in the frontal and temporal lobes. Both volumetric
and anisotropy changes in white matter over time appear to be in the
direction of effacement of between-groups differences among schizophrenia
patients and controls. Tract angles and total length were
reduced in schizophrenia, but less altered over time.
RS3.
CLINICAL FEATURES AND PHARMACOLOGICAL
TREATMENT OF BIPOLAR MIXED DEPRESSIONS
RS3.1.
THE “TROUBLED WATER” OF TREATMENT
OF BIPOLAR MIXED DEPRESSIONS
F. Benazzi
Hecker Psychiatry Research Center, Forlì, Italy; University
of California at San Diego, CA, USA
Bipolar depressions are difficult to treat. Mood stabilising agents are
more effective for mania than depression. Only olanzapine/fluoxetine
combination and quetiapine are FDA-approved for bipolar (type I)
depression, but none of the antidepressants used in unipolar depression.
While some controlled studies on bipolar depression have shown
that antidepressants are not better than placebo or lithium, some large
naturalistic studies (closer to “real-world” patients) have shown effectiveness
of antidepressants. As bipolar depression is often mixed (i.e.,
with concurrent manic/hypomanic symptoms), and most antidepressants
studies have not been stratified according to mixed status, the
results of these studies are questionable, as bipolar mixed depression
may be worsened by antidepressants (statistically wiping out positive
32 World Psychiatry 8:S1 - February 2009