ABSTRACT
Concerning schizophrenia, Adolph Meyer (1950±52) stated over 90 years ago: ``We are justi®ed in directing our attention to factors we see at work in the life histories of our patients instead of resorting to mystifying theoretical assumptions.'' Many of these mystifying assumptions are still with us, although some may be less mystifying thanks to the advances in neurobiological research during the last several decades. These produced ®ndings that are relevant ``factors'' as they distinguish neurotransmitter functions and aberrations in some schizophrenic patients as compared with other patients. But even so, the role of these transmitter differences, most notably in the dopamine-dependent network, as well as their etiological signi®cance, remain ``mysterious.''
