Screening Tools - How Is Depression Diagnosed: Depression

When other tests may be useful

There is no lab test to determine whether you have a "chemical imbalance" in the brain. Doctors who want to determine whether someone is depressed generally order tests only when they note a potential health problem during a physical exam or medical history.

Most doctors do not embark on a battery of lab tests for many reasons. Tests can be costly and may not be covered by insurance. In some cases, results point the doctor in the wrong direction, leading to more tests and unnecessary anxiety. Usually, self-reports of symptoms combined with the clinical skills of a doctor or therapist are enough to begin treatment of depression or bipolar disorder.

Sometimes, however, you may need more tests to confirm a diagnosis, tease out information, or distinguish depression from other psychological or neurological problems. Your doctor may ask you to take any of the following:

• Psychological tests, during which you answer questions, respond to pictures, or perform tasks like sorting cards or drawing pictures. These tests can give your doctor a better sense of your coping mechanisms, your temperament, or your ability to organize and plan.

• Tests that look at the brain, such as an EEG or MRI, which can help identify causes of dementia or some rare causes of depression. Both tests are painless. During an EEG, electrodes taped to your scalp pick up electrical signals. An MRI uses magnets, a radio wave transmitter, and a computer to pick up small changes in energy in hydrogen molecules in your brain and process the data to make a detailed scan of your brain.

• Tests for biological causes of depression, such as a blood test to check thyroid function.