I can only give you anecdotal information:
Our very good friend has been on Lithium for his bipolar for over 30 years, and starting about 10 years into it he started experiencing increasing tremors in both his hands to the point that 17 years into the treatment he had to quit his job as a plumber, and 30 years into it he could not write or hold a paper to be able to read from it. He ended up having a brain surgery (
www.en.wikipedia.org/wiki/Deep_brain_stimulation) to control the tremors, but it has its own side-effects... . I also read that the lithium slowly destroys the liver etc. and that people who are on it die 20 years earlier on average.
I also read that there are alternatives to lithium, though, so that may be some positive information to end this not so positive post... .