Evidence suggests that there is mitochondrial dysfunction and abnormal oxidative stress in individuals with MDD or bipolar disorder [83, 85, 86, 107–118]. Mitochondria regulate energy production and generation of ATP through the mitochondrial electron transport chain (ETC). During this process, reactive oxygen species (ROS) are produced, which can lead to oxidative stress and cellular damage, particularly in the absence of antioxidant defenses [117, 119]. Dysfunctional mitochondria can result in neuronal damage via multiple mechanisms: decreased ATP production, oxidative damage of membranes and DNA, abnormal calcium sequestration, and apoptosis [114, 117, 119].
