ABSTRACTS - World Psychiatric Association

tainty, which, in turn makes it possible to track through regions of low
anisotropy, where streamline methods fail, was applied to extract left
and right AF. After fiber extraction, mean connectivity, mean fractional
anisotropy (FA), mean diffusivity, as well as mean parallel and perpendicular
diffusivity were calculated, and compared between groups.
Volume of left inferior frontal gyrus (which includes Broca’s area) was
decreased in schizophrenia. In addition, FA, FA weighted by connectivity
and perpendicular diffusivity were decreased in schizophrenia,
compared to controls. Results demonstrate that stochastic tractography
methods extract tracts that could not otherwise be extracted.
Results also document decreased white matter integrity of AC, a fiber
tract involved in language processing, in schizophrenia.
NRS13.4.
EEG ALTERATIONS IN THE PRODROMAL PHASE
OF SCHIZOPHRENIA
U. Gschwandtner, M.O. Pflüger, V. Semenin, M. Gaggiotti,
A. Riecher, P. Fuhr
Psychiatric Outpatient Clinic and Department of Neurology,
University Hospital of Basel, Switzerland
This study explored EEG alterations in individuals with an “at risk
mental state” for psychosis and in patients with a first episode of psychosis
(FE) in comparison to healthy controls (HC), with the aim to
predict the development of psychosis. Seventy-three patients (42
ARMS, 31 FE) and 35 HC were investigated. ARMS patients were followed
up in order to monitor transition to psychosis. At study baseline
EEG was recorded using the 10/20 system. Two neurologists,
blinded to the subjects group, analyzed the EEGs visually for presence
of generalized or focal slowing and epileptiform discharges. For
statistical analyses we used chi square tests, logistic regression,
ANOVA, and receiver operating characteristics (ROC). Patients
showed significantly more pathological EEG findings than healthy
controls (p