Depression Causes

The causes of depression are complex. Genetic, biological, and environmental factors can contribute to its development. In some people, depression can be traced to a single cause, while in others, a number of causes are at play. For many, the causes are never known.

• Currently, it appears that there are biochemical causes for depression, occurring as a result of abnormalities in the levels of certain chemicals in the brain.
  
  
  • These chemicals are called neurotransmitters.
    
    
  • The abnormalities are thought to be biological and are not caused by anything you did.
    
    
• While we still don't know exactly how levels of these neurotransmitters affect mood, we do know that the levels can be affected by a number of factors.
  
  
  • Heredity: Certain types of depression seem to run in certain families. Research is ongoing as to exactly which genes are involved in depression. Just because someone is your family has depression, however, doesn't mean you will. Sometimes, family members who were known to abuse alcohol or other drugs were unwittingly trying to improve their mood (often called "self-medication" by professionals). Likewise, you can become depressed even if no one else in your family is known to have depression.
    
    
  • Personality: People with certain personality traits are more likely to become depressed. These include negative thinking, pessimism, excess worry, low self-esteem, overdependence on others, and ineffective responses to stress.
    
    
  • Situations: Difficult life events, loss, change, or persistent stress can cause levels of neurotransmitters to become unbalanced, leading to depression. Even happy events, such as childbirth, can be stressful and cause postpartum depression.
    
    
  • Medical conditions: Depression is more likely to occur with certain medical conditions. These "co-occurring" conditions include heart disease, stroke, diabetes, cancer, hormonal disorders (especially perimenopause or hypothyroidism, known as "low thyroid"), Parkinson disease, and Alzheimer disease. Clinical depression should not be considered a normal or natural reaction to illness.
    
    
  • Medications: Some medications used for long periods, such as prednisone, certain blood pressure medicines, sleeping pills, and even birth control pills in some cases, can cause depression.
    
    
  • Substance abuse: While it has long been believed that depression caused people to misuse alcohol and drugs in an attempt to make themselves feel better (self-medication), it is now thought that the reverse can also be the case; substance abuse can actually cause depression.
    
    
• Diet: Deficiencies in certain vitamins, such as folic acid and B-12, may cause depression.
  
  
  • Certain people are more likely to develop clinical depression. The following are risk factors for depression in adults:
    
    
    • Female sex
      
      
    • Advanced age
      
      
    • Lower socioeconomic status
      
      
    • Recent stressful life experience
      
      
    • Chronic (long-term) medical condition
      
      
    • Underlying emotional or personality disorder
      
      
    • Substance abuse (such as alcohol, sleeping medications, medications for panic or anxiety, or cocaine)
      
      
    • Family history of depression, especially in a close relative (such as parent, brother or sister, or child)
      
      
    • Lack of social support
      
      
  • Many of these risk factors also apply to children. Other risk factors for depression in children include the following:
    
    
    • Continual mental or emotional stress, at home or at school
      
      
    • A recent loss
      
      
    • Attention, learning, or conduct disorder
      
      
    • Obesity
      
      
  • Risk factors for depression in elderly people include those listed for adults. Especially important are the following:
    
    
    • Co-occurring illnesses: These become much more important risk factors in the elderly because of the higher incidence of these illnesses in older people. Diseases with which depression is more likely to occur include heart disease, stroke, diabetes, cancer, thyroid disease, Parkinson disease, and Alzheimer disease--all diseases that are much more common in elderly people than in other age groups.
      
      
    • Medication effects: Like co-occurring illnesses, medication use is much more common in the elderly. Depression is a side effect of some medications in the elderly.
      
      
    • Not taking medication for medical conditions: Some medical conditions, if untreated, may cause depression. An example is hypothyroidism (low thyroid).
      
      
    • Living alone, social isolation
      
      
    • Being recently widowed