Addiction as dealing with trauma as an adaptation to trauma growing up and it causing a disconnection from ones natural self. Something as simple as living in a good family and saying nothing too bad ever happened is missing the point. We dont remember what Did not happen. And thats the other side of the trauma coin. Its either something that shouldn't have happened, happened OR its something that should have happened Didn't happen.
And humans do not remember things that Didn't happen. So if you ask they will have almost nill memory of it because your asking them to remember a Lack of something and the brain doesn't do that. Chemical imbalance....sure, but? But you have to remember its the environment we have grown up in and currently live in that effects our chemical balance. One may be compensating for something he never got enough of in his life - Attention, love, energy, connection, etc.
Because as a kid if you dont have the words to describe something you " Act Out " and or do anything to try and make a point by imitating some behavior we haven't got the word for, like mirroring some one else or something...and if you dont get what you need you act out and if someone doesn't pick up on what your really trying to get at then you will eventually just disconnect from the pain of yourself through tuning out and dissociating - just like the mouse that is caught by the cat it dissociates and stays still because if your tuned out getting eaten isn't that bad.
My dad and mom were both workaholic doctors who loved me but Didnt ever give me the time of day or when he did I knew he was off in his own world thinking of his next patient problem puzzle to solve or something like that ( we did have some good bonding times but not nearly enough for Me to have what my immature brain needed for a healthy well adapted brain and coping skill set).
That and when in my developmental years being in a environment at school and in the neighborhood where I sometimes I had to fight to protect myself from being bullied by racist people always had my body on high alert so that I would be ready , and some other abuses that happened without being noticed all set the stage I think. That and family problems that went from a great family with good times together to the family splitting up and there being fighting amungst relatives ended up separating me from good role models and cousins who were my friends etc, oh and moving all the time when young too... so many thing set the stage.
This all effects a child and can cause trauma or disconnect from the self. If you think im full of shit read up on some of the more enlightened pioneers in the field of health care from the biopsychosocial models that rely on evidence and not just what was taught in medical school 10/20/30/40/50 years ago that erroneously used a model that looked at health and illness from a perspective that kept the mind and body separate (which can have its use in a model, but in actuality is the furthest thing from the living truth of things ie. they are One thing only divided by conceptual language and/or they are 2 sides of same coin)
Examples of pioneers like Peter Levine, and Dr. Gabor Mate just to name 2 people who's work and study have greatly brought real sense and greater insight into this issue which we face now more than ever today in a society that is sick in itself in large part from being based on flawed ideology etc.