 This along with the finding of increased F2-isoprostanes levels found in blood, urine and cerebrospinal fluid indicate increased damage to lipids and DNA in people with MDD.Studies with 8-Oxo-2' Deoxyguanosine varied by methods of measurement and type of depression, but F2-Isoprostane level was consistent across depression types.Authors suggested lifestyle factors, dysregulation of the HPA axis, immune system and autonomics nervous system as possible causes.