This bullshit has got to stop. Let me explain neurochemical imbalances generally, once and for all.
Your brain is a machine to enact your choices. "You" are a small part of your brain; the executive center that makes moral judgements about potential courses of action and makes plans to get what you want.
Your brain has reference ranges of neurochemicals. When it is within those ranges, you have a full spectrum of choice available to you, with no particular physiological bias toward one choice over another. A healthy brain enacts "your" whims at precisely the weightings you give them. You have all the options.
When one of your neurochemicals falls out of the reference range, your brain enacts your choices in a biased manner. Your options become impaired. You no longer have the freedom to do exactly what you want.
In clinical depression, choices that would lead to positively-charged emotional stimuli (going out for a walk instead of laying on your bed doing nothing, for example) are down-weighted. Your brain is taking away "your" choice about whether to enjoy something.
In social anxiety, choices that would lead to socially-complex interactions (seeing friends; taking university courses; working in a job involving customer service) are down-weighted. "You" might enjoy doing these things, but your brain won't let you do them.
In ADHD, choices that would lead to short-term effort but only long-term reward (practicing an instrument, for example) are down-weighted. "You" want to learn to play the piano? Too bad; your brain doesn't.
These are not facets of personality. These are impairments in your available choices, just as much as missing a leg impairs your ability to choose to go dancing or being nearsighted impairs your ability to choose to sit at the back of a classroom.
And like the physical impairments, they have prosthetics—drugs that return your brain to the reference ranges of these neurochemicals. Like any prosthetic, the point of them is to give you back the options that having the impairment takes away.
Anti-depressants let you choose to go do something fun. You don't have to. You can stay in. But the choice is no longer being made for you, by your brain.
Anxiolytics let you choose to socialize. You don't have to. You can be an introvert. But now you don't have to worry about someone making a demand of you based on an expectation that all the options are equally easy.
ADHD medication lets you choose to work on a task with no short-term reward. You can still play video games or goof off, but now you can also start—and finish—writing a book. You no longer have to select from the subset of hobbies and jobs your brain is willing to put up with.