In 2015, the National Institute of Mental Health (NIMH) estimated that 16.1 million American adults suffered from a major depressive episode. Although depression can affect anyone, certain factors may increase your likelihood of developing the disorder.

Biochemical factors

Depression is a type of mood disorder that some believe is triggered when neurotransmitters in the brain are out of balance. Neurotransmitters are chemical messengers that help the brain communicate with other parts of the body. These chemicals help regulate many physiological functions.

Low levels of neurotransmitters may play a role in why some people are more susceptible to depression, including the neurotransmitters:

  • serotonin
  • norepinephrine
  • dopamine

Genetic factors

Having an immediate family member with depression or a mood disorder can increase your risk for depression. The American Psychiatric Association (APA) states that if one identical twin is diagnosed with depression, the other twin has a 70 percent chance of developing it.

However, depression can occur in people with no family history, which is why some scientists believe it can be a product of both genes and life experiences.

Sleep disorders

Chronic sleep problems are associated with depression. Although experts don’t know if a lack of sleep causes depression, bouts of low mood do seem to follow periods of poor sleep.

Serious illness

The pain and stress that come with certain conditions can take a toll on a person’s mental state. Many chronic conditions are linked to higher rates of depression, including:

  • chronic pain
  • arthritis
  • heart disease
  • diabetes
  • thyroid disease
  • stroke
  • cancer
  • multiple sclerosis
  • Alzheimer’s disease
  • dementia
  • Parkinson’s disease
  • Huntington’s disease


People who were neglected or abused as children have a high risk for major depression. Such negative experiences can cause other mental disorders as well.


Women are twice as likely to have depression as men, but this may be due to the fact that more women seek treatment for their symptoms than men. Some believe depression can be caused by hormonal changes throughout life. Women are particularly vulnerable to depression during pregnancy and after childbirth, which is called postpartum depression, as well as during menopause.

Lack of social support

Prolonged social isolation and having few friends or supportive relationships is a common source of depression. Feelings of exclusion or loneliness can bring on an episode in people who are prone to mood disorders.

Major life events

Even happy events, such as having a baby or landing a new job, can increase a person’s risk for depression. Other life events linked to depression include:

  • losing a job
  • buying a house
  • getting a divorce
  • moving
  • retiring

The death of a loved one is certainly a major life event. Great sadness is a major part of the grieving process. Some people will feel better in a matter of months, but others experience more serious, long-term periods of depression. If your grieving symptoms last more than two months, you should see your doctor to be evaluated for depression.

Substance abuse

In many cases, substance abuse and depression go hand-in-hand. Drugs and alcohol may lead to chemical changes in the brain that raise the risk for depression. Self-medication with drugs and alcohol can also lead to depression.


Certain medications have been linked to depression, including:

  • blood pressure medication
  • sleeping pills
  • sedatives
  • steroids
  • prescription painkillers

If you are taking any such medications, speak to your doctor about your concerns. Never stop taking a medication without first consulting your physician.

If you or someone you know is suffering from depression, it’s normal to want to know what has caused it. The truth is that depression is a complex medical condition that still isn’t completely understood. The good news is that depression is highly treatable, and there are many sources of help and support in dealing with the condition.

Read more: How can I get help for depression?