Every year, I like to talk a little bit about an invisible illness that many of us suffer from, but very few people are aware of the facts surrounding it. That affliction is depression, and it's still very misunderstood by those who have not personally experienced it.

Clinical depression isn't just feeling sad once in a while, or naturally grieving for a period of time after a sad life event. There's more to it, and it can seriously affect your day to day life. Here's how it's defined by the National Institute of Mental Health:

"Major depressive disorder, or major depression, is characterized by a combination of symptoms that interfere with a person's ability to work, sleep, study, eat, and enjoy once-pleasurable activities. Major depression is disabling and prevents a person from functioning normally. Some people may experience only a single episode within their lifetime, but more often a person may have multiple episodes."

There are many different forms of depression, some of which are:

Dysthymic disorder, or dysthymia, is characterized by long-term (2 years or longer) symptoms that may not be severe enough to disable a person but can prevent normal functioning or feeling well. People with dysthymia may also experience one or more episodes of major depression during their lifetimes.

Minor depression is characterized by having symptoms for 2 weeks or longer that do not meet full criteria for major depression. Without treatment, people with minor depression are at high risk for developing major depressive disorder.
Some forms of depression are slightly different, or they may develop under unique circumstances. However, not everyone agrees on how to characterize and define these forms of depression. They include:

Psychotic depression, which occurs when a person has severe depression plus some form of psychosis, such as having disturbing false beliefs or a break with reality (delusions), or hearing or seeing upsetting things that others cannot hear or see (hallucinations).

Postpartum depression, which is much more serious than the "baby blues" that many women experience after giving birth, when hormonal and physical changes and the new responsibility of caring for a newborn can be overwhelming. It is estimated that 10 to 15 percent of women experience postpartum depression after giving birth.¹

Seasonal affective disorder (SAD), which is characterized by the onset of depression during the winter months, when there is less natural sunlight. The depression generally lifts during spring and summer. SAD may be effectively treated with light therapy, but nearly half of those with SAD do not get better with light therapy alone. Antidepressant medication and psychotherapy can reduce SAD symptoms, either alone or in combination with light therapy.²

Bipolar disorder, also called manic-depressive illness, is not as common as major depression or dysthymia. Bipolar disorder is characterized by cycling mood changes—from extreme highs (e.g., mania) to extreme lows (e.g., depression). More information about bipolar disorder is available.

What are the signs and symptoms of depression?

People with depressive illnesses do not all experience the same symptoms. The severity, frequency, and duration of symptoms vary depending on the individual and his or her particular illness.
Signs and symptoms include:

Persistent sad, anxious, or "empty" feelings

Feelings of hopelessness or pessimism

Feelings of guilt, worthlessness, or helplessness

Irritability, restlessness

Loss of interest in activities or hobbies once pleasurable, including sex

Fatigue and decreased energy

Difficulty concentrating, remembering details, and making decisions

Insomnia, early-morning wakefulness, or excessive sleeping

Overeating, or appetite loss

Thoughts of suicide, suicide attempts

Aches or pains, headaches, cramps, or digestive problems that do not ease even with treatment.

What illnesses often co-exist with depression?

Other illnesses may come on before depression, cause it, or be a consequence of it. But depression and other illnesses interact differently in different people. In any case, co-occurring illnesses need to be diagnosed and treated.

Anxiety disorders, such as post-traumatic stress disorder (PTSD), obsessive-compulsive disorder, panic disorder, social phobia, and generalized anxiety disorder, often accompany depression. PTSD can occur after a person experiences a terrifying event or ordeal, such as a violent assault, a natural disaster, an accident, terrorism or military combat. People experiening PTSD are especially prone to having co-existing depression.

In a National Institute of Mental Health (NIMH)-funded study, researchers found that more than 40 percent of people with PTSD also had depression 4 months after the traumatic event.

Alcohol and other substance abuse or dependence may also co-exist with depression. Research shows that mood disorders and substance abuse commonly occur together.

Depression also may occur with other serious medical illnesses such as heart disease, stroke, cancer, HIV/AIDS, diabetes, and Parkinson's disease. People who have depression along with another medical illness tend to have more severe symptoms of both depression and the medical illness, more difficulty adapting to their medical condition, and more medical costs than those who do not have co-existing depression. Treating the depression can also help improve the outcome of treating the co-occurring illness.

What causes depression?

Most likely, depression is caused by a combination of genetic, biological, environmental, and psychological factors.

Depressive illnesses are disorders of the brain. Longstanding theories about depression suggest that important neurotransmitters—chemicals that brain cells use to communicate—are out of balance in depression. But it has been difficult to prove this.

Brain-imaging technologies, such as magnetic resonance imaging (MRI), have shown that the brains of people who have depression look different than those of people without depression. The parts of the brain involved in mood, thinking, sleep, appetite, and behavior appear different. But these images do not reveal why the depression has occurred. They also cannot be used to diagnose depression.

Some types of depression tend to run in families. However, depression can occur in people without family histories of depression too. Scientists are studying certain genes that may make some people more prone to depression. Some genetics research indicates that risk for depression results from the influence of several genes acting together with environmental or other factors.

In addition, trauma, loss of a loved one, a difficult relationship, or any stressful situation may trigger a depressive episode. Other depressive episodes may occur with or without an obvious trigger.

For more facts and statistics on depression, visit my previous posts, helpguide.org and the National Institute of Mental Health.

If you are experiencing thoughts of suicide, please call the National Suicide Prevention Lifeline, 1-800-273-TALK (8255).

Speaking on a personal level, depression deeply affects me. Sometimes it's this overwhelming weight on my mind and body, a dark cloud over my head and a feeling like I'm carrying the world on my shoulders while walking through deep mud. It can make even simple tasks seem impossible; it destroys my concentration; it hampers my motivation.

There are many ways to help someone with depression, but you know what really doesn't help? People who tell me "Snap out of it!," "Just cheer up!," "What do you have to be depressed about? There are people who have it much worse than you!." "Happiness is a choice!". Do you really think that I want to be depressed? That I love feeling like shit? That I can just flip some magical switch and everything will suddenly become sunshine and rainbows?? That invalidating my feelings will actually somehow make me feel better? Be kind and supportive toward your friends with depression. You may not understand what they're going through, but a sympathetic and non-judgmental ear can make a world of difference to them.

Anyway, now that all that uncomfortable personal stuff is out of the way, how about some cheerful nail spam? The color for depression awareness is green, and that just so happens to be one of my most favorite polish colors.

And for everyone out there reading this that's going through depression, don't despair. You're not alone in this. There are people who understand and you don't have to suffer in silence. We're here for you.