Treatment-resistant depression: resistant to definition?

Objective: To better define treatment-resistant depression (TRD) so as to assist clinical management and refine treatment guidelines. Method: In this study, we examine a broad range of clinical variables in depressed patients (n = 196) referred to a tertiary referral Mood Disorders Unit (MDU). Information was collected from patients, referrers and assessors over a period of 32 months and included evaluations of treatments, treatment resistance and related variables. Data were analysed across trichotomized 'high', 'low' and 'no' treatment resistance groupings of patients. Results: A significantly greater proportion of patients with melancholia were amongst the high TRD group, and this was consistent across different strategies for evaluating melancholia. Conclusion: Melancholia perhaps provides a prototypic TRD subset that perhaps reflects some innate aspects of melancholic depression or factors such as the impact of ageing. Research into TRD is needed to both replicate this finding and perhaps explicate it further.