Depression Overview

Depression Diagnosis

Light therapy can help combat Seasonal Affective Disorder (SAD). Visitors sit in the Light Lounge in London.
Light therapy can help combat Seasonal Affective Disorder (SAD). Visitors sit in the Light Lounge in London.
John D. McHugh/AFP/Getty Images

Depression is a highly-treatable clinical illness and early treatment has the greatest effect. But first, it needs to be determined if the symptoms suggest a temporary case of the blues or point to a depressive illness.

There's no easy test, like a blood test or X-ray that diagnoses depression. Major depression is diagnosed based on criteria from the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV). The criteria call for the presence of at least five symptoms that last at least two weeks. Chronic depression is diagnosed with fewer symptoms than major depression [source: Mental Health America].

For some people, symptoms of depression occur only in the wintertime, a sign of Seasonal Affective Disorder (SAD). This mood disorder is associated with depression and has similar symptoms; a diagnosis is typically made after three consecutive winters.

The first step toward diagnosis of any mood disorder is to visit a doctor. Many people begin with their family doctor. While a family doctor is able to diagnose and treat mental illness, he or she will often refer the patient to a mental health professional. A doctor will first complete a physical examination and an evaluation of family history. Then he or she will talk with you about your symptoms and your mood -- determining what symptoms are present, when they began, what medications you take and your general state of mind.

To rule out other illnesses that may cause depression-like symptoms, your doctor might order the following lab tests:

  • Complete blood count (CBC)
  • Thyroid function tests and thyroid-stimulating hormone (TSH) level
  • BUN and creatinine, used to check for kidney problems
  • Electrolytes
  • Serum toxicology screen, to detect the drugs in your system

Other diagnostic tests may include imaging, such as a CT scan or MRI, or an electrocardiogram (ECG), to test the electrical activity of your heart (to rule out heart diseases) and an electroencephalogram (EEG) to test the level of electrical activity of your brain (to rule out illnesses such as epilepsy).

  • Psychometric tests may be given, including:
  • Zung Self-rating Depression Scale, a questionnaire used to screen for affective, psychological and somatic symptoms of depression
  • Beck Depression Inventory (BDI), used to assess depression based on criteria from the DSM-IV
  • Criteria for Epidemiologic Studies-Depression (CES-D) scale, a common screening test used to help individuals identify depressive symptoms

And depending on age:

  • Children's Depression Inventory (CDI), to assess signs of depression in children ages six to 17 years old.
  • Yesavage Geriatric Depression Scale, used to measure depression in older adults.

Most screening tests are relatively sensitive (80 to 90 percent) and are quick and easy to administer [source: U.S. Preventative Services Task Force].

Once diagnosed, a person has a number of treatment options. Next, we'll look at the most common treatment methods along with some popular alternative therapies. Can depression be treated with exercise and herbs?