International Journal zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Psychophysiology, 10 (1991) 271-280 0 1991 Elsevier Science Publishers B.V. (Biomedical Division) 0167~8760/91/$03.50 271 PSYCHO 00315 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Brain functional imaging in senile psychopathology Guido Rosadini, Paolo Cogorno, Stefano Marenco, Flavio Nobili and Guido Rodriguez Institute of Neurophystopathology Unioersity, and Centre of Neurophysrology of National Research Centre, Genoa (It&) Key work Electroencephalogram; Regional cerebral blood flow; Mapping system; Aging brain Quantified electroencephalogram (EEG) and regional cerebral blood flow (rCBF) measurements are reliable and currently employed techniques in the functional exploration of the aging brain; they can be routinely employed, since discomfort to the patient is minimal. Topographical analysis of EEG and rCBF results is performed in our laboratory by a fully automated mapping system, which also enables statistical comparisons in real time. The goal of our study is to ascertain if there are systematic modifications in the topographic distribution of rCBF and EEG parameters in normal aging, dementia, cerebrovascular disease and in conditions of increased risk for cerebral pathology (e.g. hypertension). Dementias and cerebrovascular pathologies present characteristic brain functional abnormalities, which can be detected by comparing the patient data to an age-matched normal population by the appropriate statistical tests; therefore, the accurate selection of healthy aged controls appears as a crucial issue in order to improve the sensitivity of statistics. INTRODUCTION The assessment of brain function is currently achieved either by electrophysiological techniques or by methods able to measure cerebral blood flow and/or metabolism. Among the latter, the 133-Xenon inhalation method (Obrist et al., 1975) for the measurement of regional cerebral blood flow (rCBF) has the best cost-to-benefit ratio. It is an atraumatic technique, which allows quantita- tive rCBF estimation with a low radiation ex- posure and little discomfort for patients. More- over, a good correlation between rCBF and re- gional metabolism was shown in normal subjects (Raichle et al., 1976) as well as in many pathologi- cal conditions (Gibbs et al., 1985; Frackowlak et al., 1981; Bernhardi et al., 1983), so that, as a general rule, rCBF may be considered at the same Correspondence: G. Rosadini, Institute of Neurophysiopa- thology, University of Genoa, Viale Benedetto XV, 10, 16132 Genova, Italy. time as an index of vascular patency and as an indirect measure of cerebral metabolism. rCBF Method In our laboratory, we employ a 32 probe (16 over each hemisphere) device (Novo Cerebrograph 32~); the probes are positioned on the skull in fixed and reproducible positions by an helmet; the air/l33-Xenon mixture is administered during one minute, followed by 10 minutes of normal air breathing. Data are collected and analyzed by the algorithm developed by Obrist et al. (1975); the initial slope index (ISI; Risberg et al., 1975) Is considered for data analysis, since it is regarded as the most reliable in several pathological condi- tions. Expired end-tidal pC0, is monitored, but IS1 values are usually not corrected for the indi- vidual CO, values, as suggested by others (Blauen- stein et al., 1977). Quantified EEG The Electroencephalogram (EEG) is routinely recorded, for 20 n-tin, with the subject sitting on a