Major depression is a type of depression which sadness and disinterest in once-enjoyed activities interfere with how you function every day. The DSM-IV states that someone who suffers from major depression must have depression symptoms such as loss in interesting in once enjoyed activities for at the least a two week period. Other symptoms include, feeling depressed for most of the day, nearly every day, loss or increase in apatite, insomnia or hysteria, Fatigue or loss of energy nearly every day, Recurrent thoughts of death, Feelings of worthlessness, and Diminished ability to think or concentrate. If a person has suffered from the fallowing manic, hippomanic, or mixed episodes (e.g., a bipolar disorder) or if the depressed mood is better accounted for by schizoaffective disorder and is not superimposed on schizophrenia, schizophreniform disorder, delusional disorder or psychotic disorder, or if depressed mood is caused by substances (such as drugs, alcohol, medications) the depression  is not considered to be major depressive disorder. Major depressive disorder is theorized to be caused by a combination of brain chemistry, family history, and psychosocial environment. levels of the neurotransmitters nor epinephrine, serotonin, and dopamine are closely linked with depression. It can’t be proven which of these factors is most affective, but each has it’s own risk factors. Genetics, from one parent, can affect a persons change of getting  major depression by 27% and double with both. Physical and environmental risk factors can increase the chance of a person having major depressive disorder, people who have a history of trauma, sexual abuse, physical abuse, physical disability, bereavement at a young age, alcoholism, and insufficient family structure. and the is a greater risk for Women during and within the first few months after pregnancy, called postpartum depression. Major depressive disorder affects 10% of men and 20% of women.