Poster Abstracts Wednesday, November 9, 2005 $305

during the middle stages. Only degree of cognitive impairment and previous rate of cognitive decline predict rate of deterioration. The relation between rate of change and severity might be due to the specific composition of the testing scales. Nevertheless it probably reflects correlation of neuropathologic and symptomatic change in Alzheimer disease, because measurement with different scale types gives similar results. Method: The simulations of dementia progression on different types of neural networks were used. Results: Several possible sources for non-linear progression of dementia were found. 1. Non-linear decline of the number of neurons. 2. Non-linear dependency of the synapses number on the linear decline of the number of neurons (for some network architectures). 3. Neural network tolerance to damage (In our model the network forgot the first pattern after removing more than 60% connections between neurons). 4. Non-linear transfer fmlction. Conclusion: Non-linear progression of dementia reflects probably fundamental properties of the neural networks.

0803 Transient Global Amnesia Associated with Mild Cognitive Impairment: Magnetic Resonance Spectroscopy Correlation

Wong HCE l, Chan YL 2, Dai DLK: . Affiliations: 1Department of Medicine and Therapeutics, Prince of Wales Hospital, Hong Kong SA R; 2Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong SAR

Background: The etiology of transient global amnesia (TGA) has been attributed to vascular insufficiency, venous congestion and migraine. Most of these patients recover completely but cognitive impairment has been shown in a small number of patients in long-term follow-up. Method: Review a case with TGA who later developed mild cognitive impairment. Results: A 74-years old Chinese lady with atrial fibrillation, hyperten- sion, gout and diverticular disease presented 3 years ago with two episodes of TGA separated by 14 months. Both episodes fulfilled Caplan's modified criteria for TGA. She did not have any memory or cognitive complaints in between these episodes. Electroencephalogra- phy was normal. Computed tomography of her brain showed age- related atrophic changes. Magnetic resonance (MR) imaging showed no cerebral infarct and there was no intracranial arterial stenosis seen on M R angiogra4Jtry. M R spectroscopy (MRS) of the posterior cingulate gyrus showed normal N-acetyl-aspartate (NAA) peak, decreased choline peak and increased myoinosital peak consistent with early Alzheimer's disease. She remained functionally well in subsequent follow-up but complained of forgetfulness 18 months after the second TGA episode. She received no formal education and her mini mental state examination score was 28/30. Clinical dementia rating was 0.5 and the cognitive subscale of the Alzheimer's Disease Assessment Scale score was 16/85. She fulfilled the diagnostic criteria of mild cognitive impairment (MCI). Her cognitive status has remained stable at her most recent follow-up. Conclusion: TGA may predate the develotnnent of cognitive impair- merit. M R spectroscopy may be used to identify at-risk patients and facilitate early treatment.

0804 PRION-1 TRIAL: Therapies For Human Priori Disease (ISRCTN06722585)

Wroe, S ~, Thomas, D ~, Rossor, M 3, Walker, A 4, Keogh, 04'5, Siddique, D ~, Webb, T ~, Pal, S ~, Darbyshire, j4, Collinge, js. 1National Priori Clinic, London, UR," 2Department. of Neurology, St Mary's Hospital, London, UK; 3Dementia Research Group, Institute of Neurology, London, UK; 4MRC Clinical Trials Unit, London, UK; 5MRC Prion Unit, London, UK

Given the progressive course of human prion disease, and no proven therapeutic options, there is an understandable desire on the part of patients and their families to access treatments with even limited evidence of efficacy. The UK Medical Research Council has established a fi'amework for the clinical assessment of therapeutic options, PRION-1, that can be refined or expanded as new agents become available. PRION-I is initially evaluating qninacrine (mepa- trine hydrochloride) which penetrates the CNS when taken orally and has a well documented toxicity profile. The rationale for its use is based on experimental data using mouse-adapted scrapie priori strains in infected cell cultures.

PRION-1 is a partially randornised patient preference trial to evaluate the safety and efficacy of qninacrine in all types of human priori disease. Patients are placed into one of 3 groups according to pre- ference: 1) randomised controlled comparison ofinm~ediate open-label qninacrine versus quinacrine deferred for 24 weeks, 2) non-randomised assessnlent of inmtediate open-label qninacrine or 3) follow-up without quinacrine treatment. All groups follow the same schedule of evaluations. The primary objective is to evaluate mortality and the proportion of "responders'" and "non-responders'" in all three cohorts based on video of neurological examination, CIBrC-plus and BPRS. Secondary objectives are to evaluate neurological and neuropsycho- logical changes, and to evaluate toxicity and tolerability of qninacrine. It is intended to expand the follow-up aml into a longitudinal prospective systematic cohort of all UK patients diagnosed with human priori disease.

0805 MRI Studies on primary progressive aphasia: a case analysis

Ymnei, Z, Yongjun, W, Yflong, W, Yue, H. Department Of Neurology, Beijing Tiantan Hospital Prince of Wales Medical Research Institute

Backgroud: To reveral where primary progressive phasia patient brain damaged, what the changes of blood flow, metabolism and connection fibers on brain by inducing the imaging characteristic of a primary progressive aphasia. Methods: Used 3.0T SIEMENS Trio 2003T and AG 2003 work station- siemens to scanning, data analyzed and imaging post processing: (1) conventionality MRI. Results; (2) magnetic, resonance spectroscopy; (13) perfusion weighted imaging; (14) diffusion tensor imaging. Results: Conventionality MRI demonstrated atrophy of left temporal lobe and fi'ontal lobe, especially left temporal pole, functional magnetic, imaging showed left frontal lobe and temporal lobe metabolism decreased, and left pole temporal and foreside of frontal lobe blood flow reduced; FA value and seeds tracing lacertus of left corticospinal tracts were reduced than that of contralateral side and the nmnber of fibers between Wemicke's and Broca's area were decreased than that o f contralateral side. Conelnsion: Major diseased regions of primary progressive phasia is located at left temporal or frontal lobe, where hypoperfusion and hypometabolism than that of contralateral side and the number of fibers between Wernicke's and Broca's area were decreased, such tlfings may be the pathologic mechanisms of aphasia.

0806 Tile hnportanee of tile detection of proviral load in PBMNC and CSF in the dilterential diagnosis between H A M / T S P and multiple sclerosis

Puccioni-Sohler M, L2's Yamano y,4 Gon~alves RG, ~.~ Vasconcelos CCF, ~ Papals-Alvarenga R, * Jacobson S 4. 2Neurological Department, ( HUGG/ EMC/ UNIRIO ) , R J, Brazil," 2 CSF Laboratory, Clinical Pathology" Service, (HUCFF/UFR)'), RJ,Brazil; 3CSF Laboratory" (NeuroFfe), -P-J, Brazil; 4NINDS, National Institute of Health (NIH), Bethesda, MD