What happens in depression, exactly?

What is it?

Depression, or major depressive disorder, is a mental disorder characterized by a persistent low mood which often leads to an inability to function normally. Depression is one of the leading causes of disability in the world. In countries like France where the rates are highest, 1 in 5 people are affected by the disorder at one point in their lives. Women are affected twice as often as men.

Depression could be described as the opposite of vitality. People with depression suffer from a very low mood, which doesn’t go away when the cause, if there is any, is removed. Simply “focusing on the positive” or doing things that have previously been enjoyable doesn’t help. People with depression often have feelings of worthlessness, guilt, self-hatred, and hopelessness. Appetite and sleep are often also affected in some way. Many depressed people have described feeling desperate in the face of the effort that normal tasks require. They might, for example, lie in bed thinking of how in order to take a shower they would have to get up, take their clothes off, open the bathroom door, and turn on the shower, and they feel overwhelmed by having to do all this. They also often say that it feels as if a veil has been lifted and they now see life accurately, and they feel like it’s impossible to ever feel better once they have understood its meaninglessness, loneliness, and cruelty. 2-7% of depressed people eventually die by suicide.

What causes it?

The exact cause of depression is not known, but it is thought to be the result of a genetic vulnerability followed by an environmental trigger. About 40% of the risk is thought to be genetic. Environmental triggers could be things like major life changes, chronic illnesses, or substance abuse problems.

What happens in it?

In mainstream media depression tends to be pictured as a chemical imbalance of the brain. Neurotransmitters are molecules that transmit signals between neurons. The lack of a certain neurotransmitter, serotonin, has in particular been advertised to cause depression. As it turns out, the truth is a bit more complicated than that.

It is true that many effective antidepressants work by raising the levels of neurotransmitters in the brain. What is surprising though, assuming that depression only happens because of an imbalance in neurotransmitter levels, is that it takes weeks for the medications to work while it only takes hours for the neurotransmitter levels to shift. This suggests that while neurotransmitters are important, they don’t tell the whole story.

The hippocampus is a part of the brain mostly associated with memory. It is intertwined with emotions for example in the way it affects the emotional responses to new and past life events based on past experiences. The volume of the hippocampus decreases in people with depression, and it is thought that stress inhibits the formation of new neurons in it. The cells in the hippocampi of mice treated with antidepressants divided significantly more after a few weeks of treatment. When the growth of these new cells was prevented, however, the antidepressants had no effect on the depression-associated behaviors of the mice. It could be that antidepressants work, because they promote cell division and the formation of new neural connections.

There are several other hypotheses of the mechanisms of depression. It might be that there isn’t one simple, unified cause of the symptoms – it might be that depression is the result of the interaction of many complicated structural, molecular, genetic, and social factors, and if any couple of things in this network go wrong, the disease appears. It might be that we’ll never find out.

How can it be treated?

Depression is mainly managed through therapy, medication, and sometimes electroconvulsive therapy. Each case of depression is different, and the treatment of each one should also be tailored to the individual needs of each patient.

Cognitive behavioral therapy is perhaps the most effective form of therapy for treating depression. Its aim is to get the patient to change their self-defeating ways of thinking and counter-productive ways of acting. It prevents relapsing particularly well.

Medication is recommended especially for patients who have severe or chronic depression. There are lots of different ones, with probably SSRIs being most famous: they work by increasing the amount of the neurotransmitter serotonin in the space between neurons. Finding a suitable medication for depression is often trickier than it sounds. Many people have to try lots of different options before discovering a drug that actually helps them. People with chronic depression may have to take medication indefinitely to avoid relapse.

Electroconvulsive therapy can be used in people who do not respond to standard depression treatment. This means inducing electrically a seizure to a patient’s brain. It’s effective, at least in the short term, for 50% of times.

There are a number of other treatment options available, and more are undoubtedly coming in the future. Depression remains one of the most significant health problems in our time. The need to come up with effective interventions, as well as increase public awareness to reduce stigma and to direct more resources to match the needs of mental health research and treatment, is immense.



Sources: http://www.health.harvard.edu/mind-and-mood/what-causes-depression, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630359/, en.wikipedia.org/wiki/Major_depressive_disorder, https://en.wikipedia.org/wiki/Biology_of_depression, 

“The noonday demon” by Andrew Solomon. I did not use this book as a direct source, but my views on depression have been influenced by it a lot – I definitely recommend reading it if you want to know more about depression. 



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