J Tiihonen, J Kuikka, P Rasanen, U Lepola, H Koponen, A Liuska, A Lehmusvaara, P Vainio, M Kononen, K Bergstrom, M Yu, I Kinnunen, K Akerman, J Karhu
There is accumulating evidence implicating involvement of frontal cortex and medial temporal lobe in experiencing and controlling of fear and anxiety. In this study, the authors studied drug-naive female patients with generalized anxiety disorder (GAD) and age- and gender-matched healthy controls with magnetic resonance imaging (MRI) and with single photon emission tomography (SPET) by using a new specific benzodiazepine receptor radioligand. Their results showed that the benzodiazepine receptor binding was significantly decreased in the left temporal pole among patients with GAD when compared with controls. This hemispheric asymmetry was studied further with a fractal analysis of the SPET images. The fractal dimension of the left hemispheric benzodiazepine receptor binding in patients was significantly higher than that of controls, and the intercept was decreased reflecting more homogenous cerebral benzodiazepine receptor density distribution in patients with GAD. The results are consistent with the general hypothesis that high regional heterogeneity of perfusion, metabolism and receptor density is necessary to maintain adaptation ability in the living organism.
For further information, please contact the corresponding author: Dr. Jari Tiihonen, University of Kuopio, Finland; Tel: +358-17-203-202; Fax: +358-17-203-494; e-mail: Jari.Tiihonen@uku.fi