Duration of illness and duration of untreated illness in relation to drug response in psychiatric disorders

Recent literature considers duration of illness (DI) and duration of untreated illness (DUI) as important factors influencing outcome in many psychiatric conditions. The aim of the present article is to analyze the relationship between DI and DUI, and pharmacological response in the different psychiatric disorders with particular emphasis on neurodegenerative aspects. An updated review of the current literature was conducted through PubMed in order to compare different studies focused on DI and DUI, and treatment response in major psychoses and in depressive/anxiety disorders. A significant body of evidence shows that a prolonged DI and DUI is associated with brain abnormalities and poor treatment response, particularly in schizophrenia. Nevertheless, an increasing number of studies point toward a similar conclusion in mood and anxiety disorders as well, even though fewer studies have been published in this field. Given the relationship between a longer DI and DUI, and poor treatment response not only in schizophrenia but also in mood and anxiety disorders - specific intervention programs aimed to reduce the latency to treatment are definitely envisaged.