If she has had such side effects from lithium, maybe she should reconsider taking it. Modern medicine (as far as psychology, and my opinion are concerned) tend to mask the symptoms, opposed to treating the underlying problem. People often repress and/or suppress trauma (whether sexual abuse, physical abuse, or mental abuse), along with various other traumas, and rarely does medication reverse that. The underlying problem (that is causing the bipolar / depression), is being "treated" by the Lithium. As in, on paper, her neurochemicals should appear "normal", although, I would assume that the depressed-thoughts and bipolar episodes continue?
If cannabis was making her happy, you would need to know:
1) Did it make her happy because it balanced something (probably a neurochemical)
or
2) Did it make her happy because she was able to escape from her problems?
She may be better off seeing a psychotherapist, or something along those lines, as medication does not sound to be helping her. Trying to find the root to the actual problem sounds more efficient than trying to mask symptomology. Taking up something like yoga, or meditation may help ease some of her anxiety and depression as well.
I am not a doctor, this is just my two cents.
I agree that you do need to keep balance in your mind, as in, not letting the bad thoughts control your life. Although, it may be beneficial that the OP's wife discuss some of the bad thoughts that she has.. something that leads to catharsis. Keeping something terrible pent up can really deteriorate your mentality.
Very true. Many people, without consciously realizing it, keep themselves in a depressed state of mind. Instead of seeing all the terrible things in life that make it suck, reinforce looking for positivity, as positive thoughts lead to positive feelings (and vise versa). When you are out looking for everything good and happy in your life, your life will eventually fill with good and happiness. Depression is a difficult habit to break, so always try to be positive and supportive (I know this can be hard at times, just remember what keeps you going as well).