I’m still reading Peter Cramer’s book Against Depression, which is his follow-up to Listening to Prozac, his groundbreaking book about depression and Prozac. This is a fascinating book, as good as Listening to Prozac. I continue to be impressed by his scholarship and ability to pull interesting research together. If you have any interest at all in learning more about depression, I would strongly recommend this book, which is a philosophical and scientific exploration of depression.

What is the natural history of depression? That is, what happens later in life if you get depressed now? Do you recover, or do you have more depressions?

We have good data on this issue from some studies funded by the National Institute of Mental Health. These studies followed depressed patients over many years. The findings are astounding, at least to me.

They show that if you are diagnosed as being depressed today, there is a 20 percent chance you will still be depressed 2 years later, and a 7 percent chance you will still be depressed ten years later, and a 6 percent chance you will be depressed 15 years later!

Even if you recovered, your probability of relapse is high. In these studies, most patients had subsequent depressions: 40 percent at two years, 60 percent at five years, 75 percent at ten years, and 87 percent at 15 years.

And with each episode of depression the prognosis worsens. After the second episode of depression, the 2 year recurrence rate soars to 75 percent!

One likely explanation for this effect is called kindling. The kindling model was first developed to explain how epilepsy works. In epilepsy, each seizure you have makes you more likely to have more seizures. This is because the seizure damages the brain.

We now think that each major depression may alter the brain as well. Particularly it may cause a shrinking of cells in several important areas of the brain. One of these is the hippocampus, which governs the formation of short term memory. Another is the prefrontal cortex, which has many functions in reasoning.

And how many patients got treatment? Only 3 percent of the patients who were diagnosed with depression had ever received even a single one month trial of anti-depressant medication! This is shameful in a country that claims to have good health care.

So what do we learn from these studies?

1. Depression is a chronic disease, and relapse is very high.
2. Each relapse makes you more susceptible to future depressions. Each depression erodes the resilience of the brain.
3. A small but substantial percentage of depressed patients remain depressed for years on end.
4. Prevention of initial depressions, early treatment of major depression, and prevention of future depressions can change the natural history of depression, and prevent a lifetime of depression.

The other important thing to realize about these studies is that they only looked at major depression. That is, at depression with many serious symptoms. Later studies that have looked at milder versions of depression have found that even mild depressions predict future major depressions. A future post will talk about minor depression, or dysthymia.

Copyright 2006 The Psychology Lounge/TPL Productions

Here is some more good stuff from Peter Cramer’s book Against Depression, which is his follow-up to Listening to Prozac, his groundbreaking book about depression and Prozac. This is a fascinating book, as good as Listening to Prozac. If you have any interest at all in learning more about depression, I would strongly recommend this book, which is a philosophical and scientific exploration of depression. Much of what follows is inspired by this book.

How big a problem is depression compared to other illnesses? Other health problems such as AIDS, arthritis, heart disease, diabetes, and cancer are much bigger problems, right?

Wrong. If you look at the impact of depression on disability, very interesting facts emerge. Let me explain how these figures are calculated. Imagine a 20 year old woman develops chronic depression that causes her to be 1/3 disabled for the next 60 years. That means she loses the equivalent of 20 years of life, which is the same as if a healthy woman died at age 60 instead of the normal lifespan of 80.

When disability from depression is calculated this way, the figures are astounding. The World Health Organization looked at this data from around the world. They found that by the year 2020 depression will be the largest cause of disability with the sole exception of heart disease. Even in 1990, depression was already the number one cause of disability within the major chronic diseases of midlife. Major depression accounted for almost 20 percent of disability-adjusted life years lost for women in the developed countries. This was more than three times the amount caused by the next illness.

Other studies looked at the impact of depression in the workplace. In the United States this cost is estimated at over 40 billion dollars, which is almost 3% of the total economy. Being depressed on the job is estimated as the equivalent of calling in sick half a day per week.

Just how common is depression? There are many studies and they often disagree, but the best studies suggest that about 16 percent of Americans will suffer a major depression over their lifetime. That is almost 1 in 6 Americans. Look around at your friends and family and co-workers, 1 in 6 of them will suffer a major depression. In any given year, between 6-7 percent suffer major depression.

And depression has major health implications. Studies that look at elderly people find that depression increases the risk of death very significantly, independent of suicide. One study found that elderly people who were depressed were 40 percent more likely to die than those who were undepressed. When they analyzed the data to see what the cause was, they found that even when you controlled for all other health behaviors and other factors, depression still accounted for 24 percent increase in deaths. This was the equivalent of high blood pressure, smoking, stroke, or congestive heart failure.

So depression is no big deal? Not unless you consider major disability, huge workplace effects, and shortened life a big deal. In reality, depression is one of the most devastating diseases that human beings suffer.

Copyright 2006 The Psychology Lounge/TPL Productions