Problem is which neurotransmitter is out of kilter, if it is the Serotonin one then Serotonin medication will suit the person, if for instance it is the Dopamine neurotransmitter then it wont. I understand there are 8 basic neurotransmitter systems: Serotonin; Endocannabinoid; Acetycholine; Opiate; GABA; Noradrenaline; Glutamate and Dopamine.
SSRI's are too often prescribed as generally the medical establishment does not have a good understanding of how the brain works. Fred Von Stieff does indepth examinations regarding family history and what substances people tend to be drawn to, he understands the imbalances of each neurotransmitter and treats every individual accordingly. There is no one size fits all.
His book Brain in Balance is cutting edge science but not too hard to understand. If the wrong drug/hormone is used this will create further imbalances and useless as a treatment.