If SSRI's are first-line treatment for depression, followed by SNRI's or NDRI's.. why is bipolar mainly treated with antipsychotics? I understand they are great for the mania part, but do they really help with the depressive episodes?

If I'm not wrong, some antipsychotics control manic episodes by lowering or "modulating" dopamine. Dopamine is good for depression. How can a substance that lowers dopamine be positive for someone with crippling depression? If you have high dopamine you might be euphoric, impulsive, outgoing...it can worsen your mania so antipsychotics make sense...but when you are bed-ridden, crying, with no energy and motivation...you either need a pro-dopaminergic, serotonergic or adrenergic drug, not an anatoginst, no?

If someone has non-bipolar depression, they are probably prescribed an SSRI, especially if the patient has anxiety disorders. Also, they might be prescribed an SNRI that also touches norepinephrine AND, if they have no anxiety issues and their depression in lethargic, they could be prescribed Bupropion (NDRI), which is pro-dopaminergic. Why do some anti-dopaminergic drugs work for Bipolar depression?

The main characteristic of Bipolar disorder is that it has both extremes and they are opposite. I can't understand how a medicine can help someone with a disorder that has completely opposite parts. It's like a drug that makes you gain weight and lose weight. It can't happen.

Could someone explain to me how antipsychotics work when it comes to de depression phase?