Methodological approaches and magnitude of the clinical unmet need associated with amotivation in mood disorders

There is growing research interest in studying motivational deficits in different neuropsychiatric disorders because these symptoms appear to be more common than originally reported and negatively impact long-term functional outcomes. However, there is considerable ambiguity in the terminology used to describe motivational deficits in the scientific literature. For the purposes of this manuscript, the term "amotivation" will be utilised in the context of mood disorders, since this is considered a more inclusive/appropriate term for this patient population. Other challenges impacting the study of amotivation in mood disorders, include: appropriate patient population selection; managing or controlling for potential confounding factors; the lack of gold-standard diagnostic criteria and assessment scales; and determination of the most appropriate study duration.

This paper summarises the search for a consensus by a group of experts in the optimal approach to studying amotivation in mood disorders.

The consensus of this group is that amotivation in mood disorders is a legitimate therapeutic target, given the magnitude of the associated unmet needs, and that proof-of-concept studies should be conducted in order to facilitate subsequent larger investigations. The focus of this manuscript is to consider the study of amotivation, as a residual symptom of major depressive disorder (MDD) or bipolar depression (BD), following adequate treatment with a typical antidepressant or mood stabiliser/antipsychotic, respectively.

There is a paucity of data studying amotivation in mood disorders. This manuscript provides general guidance on the most appropriate study design(s) and methodology to assess potential therapeutic options for the management of residual amotivation in mood disorders.