Axonal damage is implicated in the neuropathology of depression and cognitive dysfunction. Consequently, neurofilament light protein is an emerging biomarker with potential in depression and cognitive function. Results are more consistent for cognition, requiring more research to assess neurofilament light protein in depression as well as other psychiatric disorders. Future longitudinal studies are necessary to determine whether neurofilament light protein can predict the onset and progression of depression and measure the effectiveness of potential psychiatric interventions and medications.

Transitioning to bipolar disorder
Bipolar disorder is a highly heritable condition, which can progress from an asymptomatic period in at-risk individuals to a potentially debilitating illness. Identifying individuals who are at a high risk of developing bipolar disorder may provide an opportunity for early intervention to improve outcomes. The main objective of this systematic review is to