BRAIN AND COGNITION 1, 196-205 (1982) Regional Cerebral Blood Flow and Verbal Memory after Chronic Exposure to Organic Solvents V. ALEXANDER MAXIMILIAN, JARL RISBERG, ISAK PROHOVNIK, AND STEN REHNSTR~M University Hospital, Lund AND BIRGITTA HAEGER-ARONSEN University Hospital, Malmii Regional cerebral blood flow (rCBF; ‘33Xe-inhalation method) was investigated in 32 industrial workers (age: 51 ? 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents. Long-term exposure to organic solvents has been associated with CNS dysfunction and occasionally even permanent brain damage (Arlien- Sgborg, Bruhn, & Melgaard, 1978; Cohr & Stockholm 1979; Knox & This work was supported by the Swedish Work Environment Fund, the Swedish Medical Research Council (Project 25X-04969), and the Swedish Council of Social Science Research. A version of this material was presented at the Eighth International Conference of Oc- cupational Health in the Chemical Industry, Tokyo, Japan, September 1980. The authors are indebted to Siv Karlson, Helena Fern& and Marianne Glaser for aid in the measure- ments and in preparation of the manuscript. Requests for reprints and all correspondence should be sent to Dr. V. A. Maximilian, Novo Diagnostic Systems, Research Laboratory, Kantstrasse 2, 6500 Mainz, Federal Republic of Germany. 196 0278-2626/82/020196-10$02.00/O Copyright Q 1982 by Academic Press, Inc. All rights of reproduction in any form reserved.