by NamelessWolf » Wed Oct 09, 2019 4:53 pm
(Note: I write from a substance monist philosophical position; a substance dualist might describe things somewhat differently)
First things first: Depression and sadness are not the same thing. Most presentations of depression do not exclude the possibility of happiness at times. A person who seems happy, upbeat, jovial, or other pro-social presentations can still be depressed. It is better to think of depression as a flaw in normative brain functioning.
Remember that the mind is a consequence of the functioning of the brain (more precisely, it IS the functioning of the brain). That functioning depends on certain balances of certain chemicals -- not only the neurotransmitters, but also essential nutrients for cellular functioning, energetic nutrients for cellular metabolism. As well, that functioning depends on the structures of the brain -- subtle differences in formation of those structures can have significant impact on the functioning of the brain, and thus of the mind that arises from it.
The externals of a person's life, those things you can see, observe, and describe, don't necessarily correspond in obvious ways to the internals of a person's life.
You may see your friends and family as having monetary success, familial success, or other markers of quality of life. However, you have no ability to see whether their serotonin or dopamine production is normal (low levels of either are known to correlate with depression), unless you're a trained neurologist with biopsies of their brain tissue. You've no ability, unless you are a trained radiologist with fMRI access and these people in that fMRI, to observe the structural and functional organization of their brain.
Your lack of knowledge about their internal state means you cannot know what is going on in their head. Depression need not fully hamper a person's ability to function -- it certainly can, but for many people, they are able to 'go through the motions' as it were, acquiring certifications/training for building a career, maintaining a career, making social bonds, managing their life. This is because the defects leading to depression need not impair aspects of the mind known as 'executive function'. Executive function include abilities like planning, prioritizing, keeping on task, predicting outcomes, etc. While social skills typically depend on a number of aspects of the mood regulation pathways, where these are deficient, people can often navigate social scenarios via critical reasoning and logical analysis.
For some people, depression is linked to events that others can see and observe. Where this grief process takes an extended period, there can be diagnosis of certain types of depression. Treatment for event-based depression often takes the form of a course of anti-depressants to help the person return to normal functioning quickly, with therapy to process through the grief. The goal in such case is to eventually ween the person off the anti-depressants and return them to normal-for-them functioning.
People who have a problem with brain function often have life-long depression. There are known genetic variants that cause dopamine and or serotonin production to be significantly below that which is normative, for example. There are known brain structure defects that correlate strongly with depression. These things are present at birth and (with current medical approaches) cannot be corrected -- they can't be cured. Treatment in such a case usually involves maintenance dosing of anti-depressants for the rest of the person's life, along with on-going, life-long therapy to help a person navigate their mood dysregulation. A major problem doctors face with such cases is that it can often take many attempts to find just the right medication -- or even multiple medications -- to help the person treat their depression... and worse, in the process of trying to find the right 'recipe', some of the prescriptions tried can make things worse.
There are some skills that can be learned that help as well -- many people with depression either independently 'invent' or get formal training in 'mindfulness', which is a technique where one practices being aware of one's patterns of thinking, being able to identify when maladaptive thinking is happening, and using various techniques to distract from that form of thinking or willfully pointing one's thoughts in a more positive direction. This technique can be helpful in resolving event-based depression, but can only be therapeutic for those with life-long defects -- that is, it can help, but it can't remove the underlying cause.
The big take away is this -- you can't know the functioning of their brain, and depression can be functional instead of psychological in origin. As such, markers of quality of life such as a vibrant social life, a successful career, wealth, etc, cannot be used to determine if a person is not depressed, nor can absence of those markers be used to determine if a person is depressed.