I have bipolar and anxiety. I've been smoking marijuana heavily for nearly 6 years. I've also used quite alot of other drugs in that time too. Before I say this I must say marijuana has not enhanced my mental health overall, I'm guessing (can never be sure). It has exacerbated my symptoms when I don't have marijuana, quite acutely if I don't take breaks.
BUT... marijuana has always alleviated the flaws of my brain. I don't have rushing thoughts, or depressive episodes or panic attacks. I feel like 'me'. The good 'me'. It modulates my moods very well, if I'm too hypo it calms me down. If I'm depressed and in a negative spiral it raises my mood and shifts my perception of life to a very positive one.
I have taken benzos, anti-psychotics, SSRIs and none of it works, infact these drugs make me feel like a zombie and not even human. I used to take alot of benzos but not so much anymore, been on zyprexa and seroquel, both just knock me out and give me horrible side effects. Tried a few SSRIs, same deal, they made me feel worse, more anxious and empty inside with life feeling blunted. I don't take SSRIs anymore and never will again.
Yet this plant that basically cures me of these problems is illegal and not recognised as a medicine in most of the world. *sigh*
I believe that marijuana is so therapeutic for some people with bipolar due to the mechanism of action it has on the brain. THC binds with the cannabinoid receptors and modulates the flow of neurotransmitters within the brain. Essentially making them work 'closer to normal'. Either increasing their flow or decreasing their flow. This is how marijuana acts as a stimulant and a depressant, lifting your mood and stimulating you when depressed and calming you down, relaxing and sedating you when your hyper. The effects do crossover however.
What a great plant eh?