There are some genetic factors that contribute - it tends to cluster in families. But genetic pre-disposition is just one factor; just because a person has som

There are some genetic factors that contribute - it tends to cluster in families. But genetic pre-disposition is just one factor; just because a person has some genes associated with bipolar doesn't mean they will develop it. Genes associated with bipolar have overlap with genes associated with schizophrenia and autism. Bipolar is also associated with trauma in a person's life, however some people develop bipolar without any particular trauma. There is also some evidence that it could be a result of viral infection, similar to MS. There seem to be some difference in calcium channels in cells among people with bipolar, as well as sodium levels within cells. Bipolar is associated with difference in blood brain barrier permeability. Bipolar is associate with increased propensity to get eczema. There are generally some structural difference in people with bipolar's brains, although it's unclear if those are what cause the disease, if the disease causes them or if treatment causes them. Or all of the above. Basically, there are tons of potential causes, but most studies are limited by size, length and the population willing to participate in them. Study participants are often in an in-patient setting, which is generally people with a more severe form of the disorder, and is also when the disorder is at its worst, and doesn't allow for tracking the overall course of the disorder. Some long term longitudinal studies would be great