Years ago I read this book by Sydney Walker Jr. Called 'A Dose Of Sanity'. Great book. One of the basic ideas in the book was that he, as a doctor, could always find what physical problems the person was having that was causing the mental issues - IF given enough time.
He found patients with brain tumours to allergies that had, everyone, been prescribed mood altering drugs such as Prozac, Ritalin and Zoloft. Once the 'physical' situation was resolved - no more drugs.
Some recently sent me this website about mould(mold) - a real hidden toxin. Very difficult to get away from. Most of the time people don't even know it is there.
There is a lot more information on the website Survivingmold.com