What causes chemical Imbalances in the brain?

My mother told me that my father died of chemical imbalances in his brain in his mid 30's. Before this point he was on depressed, an alcoholic or bipolar etc. However he did smoke. He died within a few months. He did not act bipola or anything just beofre he died... just tired... well from what i can rember i was only 4 at the time. Just wondering what could be the causes of this is i genetic or was it caused by smoking? Als what are the symtoms?

people don't die from a chemical imbalance, you might want to talk to your mother about the cause of death. People can die from excessive alcohol consumption. A chemical imbalance can be caused from drug abuse, mental abuse, it can be genetic (majority of the times that is the case), and sometimes it can surface due to life circumstance. The only smoking that can really cause a chemical imbalance is cocaine, meth, etc. Weed will have effects on the brain but generally doesn't cause a diagnosable imbalance.

I've never heard of anyone dieing of chemical imbalances in the brain. It is probably genetic and passed through families though as it's in my family - a sister and a brother who are adults. They both have hair trigger tempers and are unpredictable to be around as they can get violent.

Your brain chemistry is made from amino acids.
Amino acids come from proteins
Proteins come from the foods we eat.
Not eating enough protein can cause chemical imbalances in certain people who are prone to that problem. Stress can upset the hormones, which can lead to imbalances.
Generally speaking, smoking wouldn't cause those problems.