The science of depression
December 19, 2013 5:31 AM   Subscribe

What are major and minor theories concerning depression and what causes it?

I am interested in the science of depression, mostly in its causes. I know that a lot is still being researched, but so far, I have heard of the following theories:

- chemical imbalance in the brain (caused by what?)
- hormones
- vitamin deficiencies
- food intolerances
- anemia
- copper toxivity syndrome (is that really a thing?)
- stress
- life changes (negative and positive)

I would especially like to know how someone suddenly gets really depressed without any known changes or causes, and how positive life changes can cause depression. Isn't that like, I don't know, saying quitting smoking causes cancer?
posted by LoonyLovegood to Science & Nature (23 answers total) 44 users marked this as a favorite
One you might want to add to your list is sleep apnea. Husbunny had crippling depression that was resistant to drug intervention. He had a sleep study and was diagnosed with sleep apnea. The CPAP changed his life. While he is still on a low dose of anti-depressants, he is so much happier, brighter, and in the moment now.

Here's an article about it.
posted by Ruthless Bunny at 5:41 AM on December 19, 2013

Isn't that like, I don't know, saying quitting smoking causes cancer?

No, it's saying that something that isn't stressful to person (marriage, birth of a child, moving etc) could be extremely stressful to another which is where resilience comes into play. In part at least.

As for current theories? Here's a lecture by Stanford Professor Robert Sapolsky that's well presented.
posted by redindiaink at 6:13 AM on December 19, 2013 [1 favorite]

Long term anger can change into depression. SAD can contribute to depression. Basically, what I half remember from some college courses, is that the brain and hormone system is VERY complex. Diet, exercise, sunlight, sleep, mood, things done on a day to day basis can all effect what chemicals the brain is getting, absorbing, or rejecting. The chemicals commonly discussed are chemicals serotonin, norepinephrine and dopamine, so if your brain is getting too little serotonin, depression can occur. A lot of the meds apparently increase the brains receptivity to serotonin et all. But this is still pretty new science, and I am clearly not a doctor.
posted by Jacen at 6:16 AM on December 19, 2013

There's also maladaptive thinking, which is what CBT tries to change.

Basically, the theory is that it's a perception and attribution disorder. The non-depressed person gets laid off, say, and goes, "Well, that's unfortunate, but times were tight and I'm sure I'll find something better." The depressed person gets laid off and goes, "Of course they laid me off, who'd want to work with me? I'm the worst person alive and I screwed up all those things. I don't deserve a job."
posted by Ghostride The Whip at 6:17 AM on December 19, 2013 [4 favorites]

Depression's Evolutionary Roots
posted by Young Kullervo at 6:25 AM on December 19, 2013

Diet, exercise, sunlight, sleep, mood, things done on a day to day basis can all effect what chemicals the brain is getting, absorbing, or rejecting.

Exactly! If you read a good book, the chemicals in your brain change. If you listen to music, the chemicals change -- different types of music, different changes. The brain and its hormones/chemicals are not static, but in a constant state of flux and every activity has an effect. Depression is a crappy result of whatever particular mixture of brain juices the depressed person is experiencing during the depressive episode.

I personally believe that the approach of "change the brain chemical levels via medication, because it's all a chemical imbalance" is too reductionistic, particularly when the individual has poor coping skills and/or trauma and abuse in the past. Therapy (different styles are better for different people) also changes brain chemicals, and when therapy is effective, it changes them for the better, plus gives the individual the tools for altering their own bad-chemical-state in future onsets of depression.

Of course, for some people, there is clearly more of a physical reason for depression. Poor nutrition, blood sugar regulation issues, gluten intolerance -- all of these can put the brain juices in a depressive state. And sleep disorders, as mentioned above. Also, SAD is a real phenomenon -- in countries near or above the Arctic Circle, light therapy is very effective at treating those who become seriously depressed during winter months where there is very little daylight.
posted by RRgal at 6:40 AM on December 19, 2013

posted by gnomeloaf at 7:10 AM on December 19, 2013 [1 favorite]

Vitamin/mineral deficiency (Omega 3 is the one I know of that has links to depression, not sure if there are others) doesn't cause depression in itself; rather it relates back to a chemical imbalance. The deal being that some people with depression may have reduced levels of certain brain chemicals, namely EPA and DHA. In those cases, supplementation with Fish Oil (which contains both those fatty acids) may help with that.

That said, there may be certain deficiencies that do cause mild depression I don't know of.
posted by Dimes at 7:54 AM on December 19, 2013

I have read that being positive for MTHFR (a comparatively minor genetic defect) can be a precursor for depression, because the defect means that the body is not able to metabolize B vitamins effectively. Hence, chemical imbalance.

Approximately 50% of the population will test positive for some form of MTHFR. It can diagnosed via blood test.
posted by vignettist at 8:33 AM on December 19, 2013

Childhood trauma plus genetic predisposition can be a pretty nasty cocktail that may lead to depression.
posted by gohabsgo at 8:47 AM on December 19, 2013 [2 favorites]

Thank you for all the answers!
What I am wondering about, mostly, is, why does depression start at a specific point of life, mostly, as it seems, in the twenties? What changes that makes people get depressed all of a sudden?
posted by LoonyLovegood at 8:52 AM on December 19, 2013 [2 favorites]

Speaking only from personal experience, my depression didn't suddenly come out of nowhere in my 20s. I was DIAGNOSED when I was in my 20s, but in hindsight it was something that had been with me for as long as I can remember. The 20s is maybe when people start to see worsening effects on their life due to their depression, and then seek diagnosis/treatment?
posted by PuppetMcSockerson at 9:00 AM on December 19, 2013 [9 favorites]

On the medical side, I'm also aware of strong associations between depression and Vitamin B12, Vitamin D, influenza, hypothyroidism, other infections and autoimmune disorders, and gut disorders like IBS. (Note that some of the causality on these is under debate; IBS could lead to depression, or depression could lead to IBS, or some common factor could lead to both. Or all three, depending on the patient.)

On timing -- well, why do certain autoimmune diseases hit at certain points? There are a ton of factors. Stress, resilience, environmental factors. I suspect the onset of things like depression and autoimmune disorders is more of a tipping point of multiple factors than it is a straight-line arrow of causation.

I also wonder if being out of school is a risk factor in the Western world -- suddenly there's no structure, no ladder to climb. I see new graduates really flounder for their first year in the working world, because most businesses don't provide the type of regular feedback and/or praise they're used to, and the career ladder may be opaque to them.
posted by pie ninja at 9:05 AM on December 19, 2013

1 in 3 of college aged students develop depression during their first few years of college due to a variety of factors, including home sickness, alienation, inability to connect to a larger community, relationship issues, and stress. That may be why it seems like a lot of individuals in their early 20s are now being diagnosed with depression and anxiety. Inability to adapt to college life (and the markers, such as failing classes or withdrawing) is also typically a strong sign of mental illness that students are forced to address, particularly if a professor or advisor becomes concerned or someone else is paying for their tuition.

However, certain types of depression, such as dysthimia, are not properly diagnosed until MUCH later in life, which is unfortunate.
posted by Young Kullervo at 9:19 AM on December 19, 2013

I was definitely suffering from depression before my twenties, but I was a teenager and I and my parents just assumed it was typical teenage angst. It was only when it got so bad that I had to drop out of college that I realized it was A Problem. Once I got diagnosed, I could see in retrospect that I'd had these feelings on and off as far as I can remember.
posted by insufficient data at 9:28 AM on December 19, 2013 [2 favorites]

I too was diagnosed in my 20s, but I was depressed as early as preschool. I remember being suicidal at 5.
posted by kathrynm at 9:46 AM on December 19, 2013 [4 favorites]

I'm a med student who just finished a psych rotation and is interested in psych. I'm not familiar with everything you listed up there, but here are some medical conditions (this list is not comprehensive at all) that can put you at higher risk for depression:

Neurologic: Parkinson's, Huntington's, MS, dementia
Malignancies: Pancreatic cancer, brain tumor
Metabolic: hyper/hypothyroid, pellagra, hyponatremia, Cushing's, Addison's, Wernicke-Korsakoff
Drugs: EtOH, cocaine, barbs, beta-blockers, digitalis, steroids, OCP, heavy metal poisoning
Infectious: tuberculosis, syphilis, mono, hepatitis
+ lupus, fibromyalgia, postpartum, etc

Finally, I'm betting the copper toxicity disease you're mentioning is Wilson's disease, a genetic disease in which the body can't excrete copper and it accumulates in the liver and brain. Depression is often seen in Wilson's.

Oh, and as for chemical imbalances in the brain--there's a lot of research out there, but one fact that always stuck with me is that research suggests that children who suffered abuse have lower levels of serotonin as adults and are at higher risk for major depression.
posted by namemeansgazelle at 1:49 PM on December 19, 2013

Make sure you consider there's Major Depression and Dysthymia. Most people mean Major Depression when they talk about Depression, but there is Dysthymia and it is a bit of a different animal. (for example, research indicates anti-depressants do work on dysthymia, more so than Major Depression)
posted by evening at 5:07 PM on December 19, 2013

It sounds on the face of it ridiculous, but I went through a spate of severe cramps and started taking a calcium/magnesium/potassium supplement. It's sold in France under the name Myocramp.

My depression lightened. If I forget to take the pill morning and night, I get depressed again. It's an on/off switch for me.
posted by jet_silver at 8:07 PM on December 19, 2013 [3 favorites]

There's a lot of recent science linking Inflammation and depression.
posted by j03 at 6:48 AM on December 20, 2013

I'll second the magnesium connection. If I constantly take magnesium then both my social anxiety and my mild depression is kept at bay and I can handle situations that would normally trigger symptoms much better.
posted by Divest_Abstraction at 8:13 AM on December 20, 2013

This is all fascinating in terms of a discussion as I would normally expect to see a lot of references to mood-altering drugs, instead I am seeing a lot of information about just the types of information I am finding out about depression. One thing I find interesting is about the role of your intestinal flora and imbalance of good bacteria to bad bacteria and how that affects mind and mood. There's a direct nervous link there between brain and gut. Gut dysbiosis can lead to the toxic elements contributing to inflammation in the brain. Probiotics measurably improves mood by increasing GABA in the brain. NPR had a nice Radiolab about this topic. Personally I find that a factor in my life, stressful life events, plus western diet leading to imbalanced flora = depressive outlook.
posted by diode at 2:17 PM on December 20, 2013

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