STRESS causes impaired performance on tests of creativity. Drugs that block β-adrenergic receptors improve test performance in patients with test anxiety. Furthermore, catecholamine precursors (L-DOPA) reduce the flexibility of semantic networks. Our study investigated the effect of noradrenergic system modulation on cognitive flexibility in problem solving. Eighteen normal subjects undertook three problem solving tasks (number series, shape manipulation and anagrams) 45 min after propranolol, placebo and ephedrine. On the task that appeared to rely most heavily on cognitive flexibility (anagrams), subjects who were most able to solve these problems demonstrated significantly shorter solution times (logarithmic scores) after propranolol than after ephedrine. This suggested that the noradrenergic system exerts a modulatory effect on cognitive flexibility in problem solving.
1Department of Neurology, Ohio State University Medical Center, Means Hall, 4th Floor, 1654 Upham Drive, Columbus, OH 43210, USA
2Department of Neurology, Bethesda Naval Hospital, Bethesda, MD, USA
3Neuropsychology Division, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
4Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
5Department of Neurology, University of Florida, and Department of Neurology, Gainesville Veterans Administration Hospital, Gainesville, FL, USA
6Corresponding Author: D. Q. Beversdorf
ACKNOWLEDGEMENTS: Supported by the Department of Veterans Affairs: Neglect in Man. Presented in abstract form at the 6th Annual Cognitive Neuroscience meeting in 1999.
Received 17 June 1999; accepted 6 July 1999