Unipolar and bipolar depression differ significantly, both neurobiologically and in clinical presentation. Existing depression rating instruments, used in bipolar depression, fail to capture the necessary phenomenonlogical nuances, as they are based on and skewed towards the characteristics of unipolar depression.
The BDRS is the first clinician-administered depression rating scale tailored to the clinical profile of bipolar depression. It includes items for rating mixed features, as well as being sensitive to many phenomenological elements found commonly in bipolar depression, such as hypersomnia and hyperphagia, which are not picked up by conventional depression measures.
The BDRS is a validated instrument for the measurement of depression in bipolar disorder. The scale has good internal validity, inter-rater reliability and strong correlations with other depression rating scales.