Take a trip inside your head to see what happens in your brain when you have depression. Hear depression sufferers talk about living with this devastating disorder, and top experts explain how depression feeds upon itself. Travel deep into the brain to zero in on the organs implicated in emotional disorders. Voyage deeper still to witness electrical impulses racing across neurons. Depression acts like a neurotoxin: view the chemicals that can cause those neurons to wither. Learn the factors that put you at risk. Discover which organs of the brain may atrophy, while others become too active. Hear a message of hope from someone who knows: even people with severe depression can become symptom-free.

Eric Baker: It was very dark. I was sad a lot. I was angry a lot.

Victoria Galucci: I would actually think other people could see it in me. So I wouldn`t want to be out tin the world.

Eric Baker: That sense of hopelessness can be just... overwhelming.

Victoria Galucci: It feels like I`m waking up in the morning and there`s this huge boulder in my bedroom and my job is to push that boulder up a hill all day long. That`s what it feels like. And at night, that boulder rolls back down rests at my bed and it`s waiting there for me in the morning.

Eric Baker: I remember thinking why, why do I feel this way. Why can`t I be happier?

VO: Depression is a mood disorder that is characterized by symptoms such as prolonged and deep sadness, decreased interest in activities that once gave pleasure, the inability to concentrate or interact with others, and having persistent thoughts of death or suicide.

VO: Depression is a disease, it`s not a choice. It`s not something one can fix by just `snapping out of it`...and it can affect anyone at any time...

Dr. Thomas Wise: About 1 in 10 people will experience a depressive disorder in their lifetime. The rate goes up for women who experience depression twice as often as men.

Dr. Vivien Burt: We could really say that depressions an illness that feeds upon itself. So that if you do have one episode you have perhaps a 50/50 chance of having a second. Having a second episode increased that risk still further to 70, 80 per cent.

Frank Bymaster: We can break the factors involved in depression down into 2 major groups: genetics and environment.

VO: Aside from depression running in the family, environmental factors that can cause or contribute to depression include: traumatic experience, pain or chronic disease, anxiety, stress or major life changes.

Victoria Galucci: I had some significant things happen that lead up to it. My mother passed away, I changed my job, I decided to move. These are big life altering things to go through .

VO: But why does depression happen, and what is happening inside the body and brain of someone with depression?

Frank Bymaster: Depression almost has a neurotoxic like affect to the brain.

Dr. Vladimir Maletic: At least two thirds of the patients who have major depressive disorder end up having elevated levels of circulating stress hormones.

VO: These types chemical changes in the brain can lead to eventual physical changes in the brain because they affect the brain`s primary cells, called neurons.

Dr. John Morrison: Neurons are the main cells in the brain that allow you to see, move, remember, learn and essentially are responsible for all information transfer in the brain and all information storage in the brain.

VO: In depressed people, neurons are affected in different ways, in different parts of the brain. Imaging studies have shown that neurons become less active and can erode.

VO: The Prefrontal Cortex is the part of the brain responsible for decision-making, personality expression and social behavior. The Hippocampus is primarily responsible for long-term memory. These parts of the brain often become atrophied and less active in patients with depression, which can affect their worldview.

Eric Baker I looked at things very black and white. Success, failure, hero, zero, positive, on or off there was no gray.

VO: Another part of the brain, called the Amygdala, becomes overactive. This is the part of the brain that controls emotional reactions.

Victoria Galucci: I personalized everything in my life. Any little mishap or, or problem of situation if something went wrong I absolutely believed it defined me.

VO: Depression can also affect other parts of your body. It has been linked to heart disease, fibromyalgia, diabetes, irritable bowel syndrome, stroke and cancer. People with depression are more susceptible to substance abuse. And people with pre-existing medical conditions, who are depressed, are less likely to take their medication and maintain a health regimen. But there is hope...

Dr. Vivien Burt: The important message to convey is that depression is a treatable illness. It`s an illness that even when it`s at it`s most severe can be treated to what we call remission which means no symptoms at all. And a person then gets back to who he or she was fully functional, able to enjoy life, able to live life.