Depression Part 1 and Intro

I’ve been wanting to put together very long-researched post on how and whether antidepressants work, their mechanisms of action, and theories of clinical depression.  However, this post is going to be LONG, and unreadably so, so instead I’m going to start with little background tidbits: depression etiology, symptoms, etc (post 1).   Types of antidepressants, and what differentiates them from each other (post 2), how scientists study depression (post 3) the serotonin hypothesis of depression (post 4), the BDNF hypothesis of depression (post 5), and how the two interact in the most recent hypothesis of depression and how antidepressants function (post 6).  Obviously this is a pretty significant writing up of information, and there will probably be some other posts (such as weird science and classic science) interspersed with them.  But people are interested, depression is big right now, and here it goes:

Post 1: Depression Symptoms and Classification
(from the work of Richard Wilkinson)
There are lots of theories out there as to what constitutes depression, whether it is over- or under-diagnosed and over- or under-treated, what causes it, and whether we should just HTFU.  Right now, depression is thought to occur in 21% of women and 13% of men worldwide, with 18 million people affected in the US (this is according to the lecture I had in 2006 on it, though other people say it’s 8-17% of the total population).  It’s a big deal for research, depression is second leading cause of disability, and antidepressants are the third best-selling group of pharmocotherapies in the world.  Not only that, the economic burden is 12.4 billion dollars a year in medical, psychiatric, and pharmacological care, and that’s not counting decreased productivity, work absences, and mortality costs for depression-related suicides (well, ok, it’s not that much when compared to the cost of the Iraq war).  Regardless of its issues in modern society, depression is both a significant emotional and economic burden, and something that goes very far back in human history. 

Major depression is also known as Major depressive disorder, unipolar depression, and clinical depression.  Many people see references to depression in the behavior of King Saul (book of Samuel, Chronicles I, believed to have lived around 1000 BCE), and the Greeks certainly noted depression in some patients, calling it “melancholia”.  Theories about it ranged from the idea of the four humors (where depression was caused by an excess of black bile), to being possessed by spirits, to being hounded by your mortal sins (which, given the persistent feelings of guilt that many depressed people feel, is not so far-fetched).  Now, of course, it is classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as a psychiatric disorder which can result from life events, biological/genetic susceptibility, or a combination of the two. 
(King Saul and David by Rembrandt)
Symptoms:  It’s not just about feeling “down”

Depression as a diagnosis can actually be broken down into typical and atypical clinical depression, as well as types of depression comorbid with other psychological disorders.  The biggest psychological symptoms used for diagnosis of major depression are a major change in mood, persistent sadness (more than two weeks in duration), thoughts of worthlessness and excessive guilt, thoughts of death, and a symptom called anhedonia, which is a lack of pleasure in previously enjoyed activities. 

But it’s not all in your head.  Major depression is characterized by physical manifestations as well.  In typical (or agitated) clinical depression, the physical symptoms include (in general) insomnia, decreases in appetite and weight loss, fatigue, and psychomotor agitation.  In atypical (or retarded) clinical depression (which may actually be more common than typical depression), there is fatigue, excessive sleeping, increases in appetite, food consumption and weight gain, and slowness of movement.  Both types show inability to concentrate, as well as withdrawal from social situations, family, and friends. 

These diagnoses do not include bipolar disorders, which have components of severe depression as well as components of mania, or depression comorbid with other disorders such as anxiety (right now we think that 58% of people with clinical depression also suffer from anxiety).   Symptoms of depression can also be caused by problems such as chronic pain, thyroid problems (like hypo- or hyper-thyroidism), HIV, or other chronic diseases, where long-term stress in the body can cause psychological disturbance. 

The DSM IV has several kinds of depression listed: 
melancholic features: insomnia and weightloss, guilt
atypical features: weight gain, sleeping, and perceived social rejection
psychotic features: including delusions and some hallucinations, though those are rare
postpartum:  I’m sure you’ve heard of this one, depression following giving birth, right now doctors think it can stem from the massive hormonal and physical changes taking place

There are also several other diagnoses which are not classified as depression, but which have depressive features as part of them:
Bipolar: this is divided into types one (with mania) and two (with hypo-, or less, mania)
Dysthymia: chronic mild depression, where you have a depressed mood for at least TWO YEARS without any major depressive symptoms (like thoughts of death or guilt), you’re just down all the time.  This makes me think of Mr. Snuffleupagus from Sesame Street when I was a kid…”ooooooh dear…”
Recurrant brief depression:  this is VERY brief, a few days or a week, but can occur as often as once a month.  In women it’s usually connected to the menstrual cycle. 
Seasonal affective disorder: usually associated with winter, though it can be any season, this is depressed mood connected with specific times of year.  Interestingly, Mary I (bloody Mary) of England probably suffered from seasonal affective disorder, which in her case occurred in the autumn.
Reactive depression: a psychological response to an outside stress, such as the loss of a loved one, moving to a new place where you don’t know anybody, etc.

Depression can be episodic, constant, and recurring.  But prognosis with continuing (even after the episode is over) psychotherapy and pharmaceuticals can be very good. 

I want to end this part with a disclaimer:  I am NOT a doctor.  Hell, right now I’m not even a PhD. Thus, I cannot tell you whether or not you have depression, bipolar, or anything else.  If you look at what I’ve listed and go “OMG, that’s me!!”, see your doctor first, and ask them. 

Next up is part 2: different pharmacotherapies for depression.

2 Responses

  1. I am looking forward to the entire series. Once it’s done, you may want to send it to the Basic Concepts page: http://scienceblogs.com/evolvingthoughts/2008/06/basic_concepts_in_science_a_li.php

  2. […] and may be only part of the real story, if it turns out it plays any role at all. I've got a couple of posts on depression at my old place, but unfortunately I never got to the serotonin vs. BDNF […]

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