illykitty
RF's pet cat
Regardless of what you mean by "related to issues with brain dysfunctions," no Major Depressive Disorder is defined or diagnosed on the basis of any objective biological measurement of "brain function".
Indeed, according to the DSM, the symptoms by which an episode of "depression" is diagnosed are overtly socially relative, i.e., depends on what is "an expectable and culturally sanctioned response to a particular event".
No idea what the way it is diagnosed with has to do with it. Yes, it is diagnosed a certain way but there's been some brain scans and other research done on the brain of depressed patients which shows differences with healthy brains. This shows a physical brain problem as well.
https://www.google.co.uk/webhp?sour...&espv=2&ie=UTF-8#q=depression brain chemistry
https://www.google.co.uk/webhp?sour...n=1&espv=2&ie=UTF-8#q=depression+brain+reward
https://www.google.co.uk/webhp?sour...pv=2&ie=UTF-8#q=depression+brain+connectivity
Here's a few links to get you started.