Top-down och bottom-up resonemang i diagnostiska sammanhang

Sammanfattning: The purpose of this study, divided into two parts, was to research and review on how nosological methods are used and can be developed in a clinical environment. A survey was performed, where 26 students that have completed a course in psychiatric diagnostics answered true or false statements about the presence of specific symptoms and their logical connection in three selected diagnoses from ICD-10. The study found large variations between respondents in the percentage number of symptom statements answered wrong, and the statements concerning logic. Partly, the large variation can be attributed to the use of top-down reasoning in the diagnostic process, and the validity of which can be affected by belief bias, strain on working memory, and availability and representativeness heuristics. The study is followed up by a theoretical hypothesis which focuses on bottom-up reasoning as an alternative approach to diagnostics, and the presentation of fuzzy logic algorithms for 186 different diagnoses as presented by ICD-10. Whilst this kind of bottom-up approach cannot fully replace top-down reasoning, there is a possibility that bottom-up reasoning and fuzzy logic algorithms can be used as a guideline in psychiatric evaluations to increase inter-judgment reliability.