Causas e Modelos Causais em Psiquiatria

Causality is of great importance in medicine and the use of causal vocabulary is perhaps inevitable. After all, interventions such as prevention and treatment depend, to a large extent, upon the knowledge about the causes of diseases. However, medical scientific literature is seldom explicit about the notions of cause and causal models employed. There seems to be high expectations of finding strong causes for the diseases, i.e., causes that are necessary and sufficient, which are rarely seen in daily practice. In psychiatry, our main concern here, there are many weak causal factors whose determination is, at best, probabilistic. Understanding the causal chain of mental disorders is, therefore, a major challenge, and this equation becomes even more complex if we include in it singular events, such as biographical circumstances. OBJECTIVE: This work aims to analyze, in a philosophically-informed way, the explicit or implicit notions of causality in the current medical scientific literature and to find out which philosophical models of causality prevail in these texts. I also suggest that the causality model of the philosopher John L. Mackie is as an alternative to the exclusive use of statistical models in scientific papers, tendency observed since the seminal work of Bradford-Hill (1964). METHODS AND RESULTS: I reviewed medical and philosophical literature through the relevant databases (PubMed and Philosopher's Index, respectively) and analyzed the concepts of cause used either implicitly or explicitly in the articles. I also made an active search through the references of the articles reviewed and considered as well books of philosophers who have addressed causality. There are important consequences of applying certain ideas of causality on empirical data, such as, for instance, deciding whether or not we should adopt an indeterministic stance of the world (distinction that implicitly appears in the contrast between the works of Koch and Bradford-Hill, for example). Another key consequence is that statistical models (which are based on regularity) face some difficulties when dealing with events that do not repeat, common occurrence in psychiatry. Moreover, the mainstream scientific research in psychiatry is leading to a growing set of empirical data with limited explanatory power about the causality of mental disorders. In that regard, the model of the philosopher John L. Mackie, called INUS condition, appear to be very helpful for rearranging the causal elements within a causal field. Mackie suggests that our notion of cause usually takes peripheral elements to be causally relevant; for him, causality is "necessity in the circumstances." Thus, he defines the notion of INUS condition as a necessary element within a set of conditions, set that is, at its turn, sufficient (though not necessary) for the effect. I explored the notion of INUS condition throughout the text and, to exemplify its feasibility and to stress its advantages, applied it to the hypothetical causal conceptualization of Schizophrenia and Post-Traumatic Stress Disorder