If you can find the chemical imbalance hypothesis online, you can also find the research that debunked that hypothesis in the 60's. At this point the chemical imbalance line is pure marketing. Think about it, if it is a chemical imbalance the person can do nothing to remedy the problem, therefore meds are the only solution, for life. If meds were effective wouldn't the cases of depression, suicide, anxiety etc be reduced? The rates are actually rising while the prescriptions for psychotropic drugs are skyrocketing. I actually wrote a paper in grad school looking at the efficacy of anti-depressants, what I found is that research funded by Pharma or Pharma linked researchers found that the meds were effective. Research independently funded fount that anti-depressants were no more effective than placebo, except that placebo did not cause suicide. There is a book called" the Emperor's New Drug" by Mark Kirsh is an eye opening read about med research and the significant flaws.