How environmental enrichment balances out neuroinflammation on chronic pain and comorbid depression and anxiety disorders

Abstract

Depression and anxiety commonly occur in chronic pain states, and the co-existence of these diseases worsen outcomes for both disorders and may reduce treatment adherence and response. Despite the advances in the knowledge of chronic pain mechanisms, pharmacological treatment is still unsatisfactory. Research based on exposure to environmental enrichment (EE) is currently under investigation and seems to offer a promising low-cost strategy with no side effects. In this review, we discuss the role of inflammation as a major biological substrate and aetiological factor of chronic pain and depression/anxiety and report a collection of preclinical evidence of the effects and mechanisms of EE. As microglia participates in the development of both conditions, we also discuss microglia as a potential target underlying the beneficial actions of EE in chronic pain and comorbid depression/anxiety. We also discuss how alternative interventions in clinical guidelines, such as EE, may improve treatment compliance and patient outcomes.