Peripheral blood biomarkers in youth with bipolar disorder: a systematic review

Abstract

Bipolar disorder (BD) is a chronic, progressive illness characterized by fluctuations in mood. It is associated with psychosocial and cognitive impairment that can affect a person’s life at home, at work or school, and in interpersonal relationships. Children and adolescents diagnosed with BD experience similar functional impairments and risk for suicidal thoughts or actions compared to adults. Additionally, they are at an increased risk for poorer prognosis during adulthood given the negative outcomes associated with early illness onset, delayed treatment, misdiagnosis, and longer illness duration. The etiology and pathophysiology of bipolar disorder is incompletely understood. Peripheral blood biomarkers can provide insight into the mechanisms underlying the disease and can aid in identifying at-risk individuals, making an accurate diagnosis, monitoring illness activity and improving therapeutic intervention. A PubMed search was carried out and 12 studies were identified that assessed potential peripheral blood biomarkers in children and adolescents with bipolar disorder. These studies suggest that fatty acid biostatus, markers of lipid and protein oxidation, markers of inflammation and immune disturbance, neurotrophic factors and enzymes related to inflammation may serve as biomarkers of BD. These potential biomarkers of the disorder warrant further study in youth with BD. Current findings support a staging hypothesis of BD wherein cumulative episodes lead to disruptions of the pathways associated with the disorder and thus greater impairment in patients farther from their disease onset. However, these and other biomarkers will need to be evaluated in larger, longitudinal studies to validate their use and expand knowledge in the field.