A combination of biological, social, genetic environmental factors contribute to depression. Depression can be caused due to the following reasons

• Constant alcohol consumption or due to drug abuse

• Social abuse or been neglected during childhood

• High stress

• Death of a friend or spouse or relative

• Mental stress

• Certain drugs can cause depression like sedative drugs

• Hypothyroidism, cancer or hepatitis like medical problems

• Lack of folate and omega-3 fatty acids in diet

• Having major illness

• Sleeplessness

• Social isolation

Biology of depression: The basic biological cause of depression can be related to the abnormality of delivery of certain neurotransmitters in the brain. The neurotransmitters regulate mood and there by the associated behaviors.

• Serotonin: Serotonin the most important neurotransmitter associated with depression. Imbalances in the serotonin levels in brain can trigger depression and other mood disorders.

• Other Neurotransmitters: Other neurotransmitters associated with depression include acetylcholine and catecholamines that includes dopamine, nor epinephrine and epinephrine or adrenaline. Corticotropin-releasing factor (CRF) is a stress hormone and a neurotransmitter this is involved in the control of depression and anxiety. An imbalance in either of the above can cause depression.