Just recently I was part of an online discussion about whether or not depression is a real medical disorder as opposed to simply being “a wrong mindset”. Having suffered from clinical depression for 20+ years, I’ve experienced most symptoms of severe depression and tried so many different medications I can’t remember all the names. In addition to my first-hand experience, I spent 15+ years working as a medical data analyst in some of the very best medical facilities in the U.S., including the world renown Cleveland Clinic. That said, I’d like to share a little of the insight and information I’ve gathered about depression over the past 20 years. (FYI, I suffer from bipolar disorder II, more specifically bipolar depression.) In the process maybe I can help clear up some things on a layman’s level.

There are two different types of depression I’d like to discuss. Both are real though only one is considered to be a serious medical condition in and of itself. But perhaps by understanding the difference, some of the confusion about depression can begin to clear up.

The first type is situational depression. This is the type of depression people experience when they've lost a loved one, or are unexpectedly unemployed and in dire financial straits, or perhaps they’re going through an emotionally painful divorce.

Situational depression exists when circumstance is the primary reason for a person feeling sad, hopeless, helpless, etc. Antidepressants are often effective in these cases because they increase the levels of certain "feel good" neurotransmitters in the brain by inhibiting their normal re-uptake, or reabsorption. In other words, antidepressants alter the normal cycle of these neurotransmitters by preventing them from moving through the brain as quickly as they normally would. They're sort of stockpiled in the brain for a while before being re-absorbed into the body.

The neurotransmitters involved include serotonin, dopamine and norepinephrine. Each of them plays a part in elevating mood; a higher level of these neurotransmitters promotes a greater feeling of well-being -- a more positive mood -- and as an added plus may even lessen existing physical pain to some degree. For example, the neurotransmitter dopamine is believed to be responsible for the "runner's high" some joggers and runners feel, though endorphins may also play a role.

People suffering from situational depression may be helped by therapy in place of, or in addition to, medication. Cognitive therapy can be extremely helpful in dealing with situational depression. This type of therapy basically involves changing the way a person looks at things so he doesn’t always see the glass half empty.

The other type of depression I'd like to discuss is the one people seem to be much more confused about: clinical depression.

Clinical depression is a serious -- and very real -- medical condition. This is the depression most often referred to as a chemical imbalance. Clinical depression has a physical disorder at the root of the problem. Thus a person suffering from clinical depression can't simply "think positive thoughts" to rid themselves of their depression. The physical problem, a chemical imbalance, must be corrected in order to ease the depression.

All the positive thinking in the world won't resolve an innate, acquired or possibly genetic chemical imbalance any more than serious positive thinking will allow an amputee to grow a new limb.

Again, clinical depression -- also called major depression -- is a medical condition and must be treated as such. Remember, it’s not just a matter of feeling down after a bad day or simply having “a wrong mindset”.

Clinical depression has sub-categories such as dysthymia, bipolar depression, seasonal affective disorder (SAD), and others which can be further defined as mild, moderate or severe.

All that said, people often wonder why antidepressants work for some people but not for others. The answer is at least three-fold.

First, it's difficult to pinpoint which neurotransmitter, or combination of neurotransmitters, is involved in the imbalance. In addition, brain synapses -- necessary and normal activity involving neurotransmitters -- aren't fully understood but may play a role in clinical depression.

Second, the cause of a neurotransmitter's deficiency is likely to be uncertain or unknown, which forces the treatment to be focused on the patients symptom(s) instead. But since symptoms may come and go as well as vary in intensity, there isn't much consistency to work with. Such inconsistency and uncertainty can affect the success of antidepressants.

Third, the type of antidepressant and the exact amount needed to treat clinical depression varies from person to person. Like many medications, what works for one person won’t work for another even though they suffer from the same disorder. Sometimes a lengthy trial-and-error process is required to find effective medication(s) and proper dosages for clinical depression. Compounding the problem is the fact that antidepressants sometimes stop working after a while if the body develops an immunity or tolerance to them. (An example is what's commonly called "Prozac poop-out".)

The frustration-flavored icing on the cake is something known as treatment-resistant depression or medication-resistant depression which is exactly what it sounds like. For whatever reason, no medication treatment is very effective, or effective at all, in treating the depression even though everything indicates it should be. There aren’t any clear-cut answers for such resistance though there are, as always, plenty of theories.

Regardless, if medication fails, the somewhat controversial electro-convulsive therapy (ECT) may be an option in cases of severe clinical depression. ECT is usually considered as a last resort though recent studies may change that thinking.

As with situational depression, some types of therapy may be of some benefit to a person suffering from clinical depression; however the therapy serves a slightly different purpose and works in a somewhat different manner. (Dissecting the pros and cons of therapy is a subject for a separate hub.)

I hope I’ve shed a little light on the subject of depression but please keep in mind that I’m not a medical authority or a licensed physician and I’m not offering any medical advice. (That's my official disclaimer.)

But to Tom Cruise and others who still doubt the reality and severity of clinical depression, I say... Shut up and put on my size 6 1/2 Nikes. The mile is all uphill on an ice-covered surface. There are deep ravines on either side of you and you're wearing a partial blindfold. Good luck and start walking.