[determining factors of depression in multiple sclerosis: review of the literature].

Depression is considered to occur more frequently in multiple sclerosis than in other chronic organic disorders. The determining factors of this specific association have been appraised by most authors in a dichotomic manner, confronting organic to psychogenic hypotheses. To assess these hypotheses two investigational methods have been used in the literature: either the search for correlations between depression and other parameters linked to the neurologic process, or the comparison of the course of neurologic and thymic symptoms. Systematically scrutinizing this literature enabled us to discuss its findings as well as its methodologic and conceptual limitations.