Biological and quantitative issues in neuropsychiatry.

During the recent resurgence of interest in neuropsychiatry, rapid technological advances have outpaced developments in the underlying theoretical framework. Neurophilosophy has tended to overlook clinical problems. This paper aims to redress the balance by examining a number of conceptual issues. Two groups of problems are considered: those related to brain functioning and psychiatric symptoms, and those related to the measurement of symptoms and their statistical analysis. It is emphasized that psychiatric symptoms appear to reflect the modular organization of the brain; and the particular psychiatric symptomatology associated with individual neurological diseases may be more distinct than is generally assumed, both cross-sectionally and over time.