Abnormal temporal lobe N-acetyl aspartate levels in first episode psychosis

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The mean volume of pineal gland in patients was 0.208 CC (Std D=0.099) and for the controls 0.213 CC (Std D=0.097). Comparison of the volumes by t test showed no significant difference between patients and normal controls (p=0.77). This study, backed by a large sample size, suggests that there are no volumetric differences of pineal gland between patients with schizophrenia and normal controls.

ABNORMAL TEMPORAL LOBE N-ACETYL ASPARTATE LEVELS IN FIRST EPISODE PSYCHOSIS Perry F. Renshaw*, Deborah A. Yurgelun-Todd, Staci Gruber, Mauricio Tohen, Bruce M. Cohen McLean Brain Imaging Center, McLean Hospital Belmont, MA 02178, USA We have previously reported a reduction in the ratio of Nacetyl aspartate (a putative neuronal marker) to creatinine (NAA/Cr), as assessed by proton magnetic resonance spectroscopy (1H MRS), in patients with chronic schizophrenia compared to patients with bipolar disorder and psychiatrically healthy comparison subjects (Yurgelun-Todd et al., Proc. Soc. Magn. Reson., 1993). In this study, 1H MRS of the temporal lobes was performed bilaterally in 13 patients hospitalized with a first episode of psychosis and 15 age-matched comparison subjects. Reductions in mean temporal lobe NAA/Cr were present bilaterally in psychotic patients (left 1.07 +0.15, right 1.07+0.22) relative to comparison subjects (left 1.21+0.17, right 1.19 ± 0.23 ). First episode patients displayed a significant reduction in NAA/Cr as determined by a repeated measures analysis of variance (F( 1,26) = 4.30, p = 0.048). These preliminary data suggest that a decreased temporal lobe NAA concentration, which is consistent with a reduction in the number, size, or physiologic state of neurons, is present early in the course of psychotic illness. To our knowledge, this is the first time that 1H MRS has been used to demonstrate a specific neurochemical abnormality in patients with a first episode of psychosis.

tionate to generalized cognitive impairment. The hippocampal formation (HF) is known to be critical for encoding new information. We applied the emergent technology of fMRI with high temporal and spatial resolution to measure changes in local cerebral blood oxygenation in the HF and adjacent temporal neocortex in patients with schizophrenia. Two experiments utilized a gradient echo sequence at 1.5T to acquire 5 mm slices through the longitudinal axis of the HF yielding a time series of 256 x 256 matrix images. Data were analyzed by ROI time-course and statistical parametric mapping (SPM). Experiment I: An auditory, low-imagery word memory task was administered during scanning. Conditions included encoding, silent free recall, and recognition. Activation was observed in the left anterior HF during encoding, although the pattern was attenuated from that seen in normal controls. During silent free recall, greater activation was seen in the left temporal neocortex. Despite severely impaired recognition memory performance, regionally appropriate activation was observed. Experiment 2: To examine material specificity, separate visual tasks were presented for words and faces. We controlled for language and perceptual processing by alternating sequences of perceive/encode instructions. The word and face tasks each consisted of eight 45 s activation trials, and each task yielded four complete perceive/encode cycles. Recognition performance for words and faces was assessed after completion of the scan. As in the first experiment, the patients' performance was severely impaired on behavioral measures but showed regionally appropriate albeit attenuated activation. Differences in spatial and time course patterns of memory activation across subjects demonstrate the potential utility of fMRI for studying the heterogeneity of schizophrenia and individual differences in brain activation.

BENZODIAZEPINE RECEPTORS IN SCHIZOPHRENIA. A STUDY WITH IOMAZENIL-SPET J. Schr6der a'*, B. Bubeck b, H. Sauer c, S. Demisch a

MEMORY ACTIVATION IN SCHIZOPHRENIA: PRELIMINARY OBSERVATIONS USING FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI) A.J. Saykin*, H.J. R i o r d a n , J.B. Weaver, T.C. M a n s c h r e c k , L.A. F l a s h m a n , E.M. K a h n , K.A. Flannery, A. M a m o u r i a n , T.W. McAllister

Departments of Psychiatry and Radiology, Dartmouth Medical School Lebanon, NH 03756 and New Hampshire Hospital Concord, NH, USA Memory is frequently impaired in patients with schizophrenia, and memory difficulties often appear early and dispropor-

aDept, of Psychiatry, University of Heidelberg, Heidelberg, Germany, bDept, of Nuclear Medicine, University of Heidelberg, 69115 Heidelberg, Germany, CDept. of Psychiatry, University of Jena, Jena, Germany Benzodiazepine receptors were investigated using single photon emission tomography (SPET) with iomazenil as a ligand. 20 DSM-III schizophrenics with both a remitting (n = 9) and a chronic (n = 11 ) course were included. In every patient, two SPET-images were taken: The first SPET-image was obtained two hours after intravenous injection of 200 MBq 1-123-iomazenil. Following the first SPET, patients received 10 mg diazepam intravenously. 20 min later, the second SPET was started. For data analysis, ratios between occipital and frontal iomazenil activity were calculated. The activity measures in each region of interest was divided by the number of pixels.