The impact of psychotropic drugs on brain functionality and connectivity in bipolar disorder

Abstract Bipolar disorder (BD) is a common, severe, and chronic psychiatric condition characterized by affective instability and disability. Functional neuroimaging techniques provide measures of brain activity and connectivity that have helped to elucidate neurobiological basis of this disorder. Indeed, functional magnetic resonance imaging (fMRI) has proven extremely useful for exploring the abnormalities in brain regions during the performance of specific tasks or in resting-state conditions. However, deeper consideration of pharmacological treatment effects on neural function may be required when considering fMRI results. In this context the aim of this chapter is to provide an overview of the evidence reported by fMRI and resting-state fMRI studies evaluating the effects of pharmacological treatment in patients with BD. Overall the available evidence supports normalizing effects of medications on brain activity/connectivity, ultimately suggesting that medications have a positive impact on neural circuitries. Specifically the majority of these studies found a normalization in prefrontal regions and interconnected areas involved in emotion regulation and processing, regardless of the task employed. Additionally, distinct classes of medications showed different results in terms of regional specificity, maybe due to their different pharmacological properties. In conclusion, these findings provide key insight on the neurobiology of BD by the identification of specific biomarkers of treatment outcome.