"
Causes
Bipolar disorder does not appear to have a single
cause but is more likely to result from a range of factors that interact."
Bipolar disorder: Causes, symptoms, and treatment
More than suggest. The incidence of those having the disorder having relatives with it is very high. More than 50%. That's the genetic factor. The paragraph below doesn't tell you why they have it, just what the results are. The hormonal imbalance is, yet again, a genetic factor.
The environmental factors theory has no basis from published studies. What is known is bipolar in general doesn't "present" till age 25 though it can manifest at any age. Once again, the genetic predisposition is there, but the trigger is not known. Drug usage can definitely be the trigger that sets it off, but once again, there has to be that genetic predisposition. If the drugs are never used, there is still a chance that it will develop at any time thanks, once again, to that genetic predisposition.
From your link
"Bipolar disorder does not appear to have a single
cause but is more likely to result from a range of factors that interact.
Genetic factors
Some studies have
suggested that there may be a genetic component to bipolar disorder. It is more likely to emerge in a person who has a family member with the condition.
More than suggest. The incidence of those having the disorder having relatives with it is very high. More than 50%. That's the genetic factor. The paragraph below doesn't tell you why they have it, just what the results are. The hormonal imbalance is, yet again, a genetic factor.
The environmental factors theory has no basis from published studies. What is known is bipolar in general doesn't "present" till age 25 though it can manifest at any age. Once again, the genetic predisposition is there, but the trigger is not known.
Biological traits
Patients with bipolar disorder often show physical changes in their brains, but the link remains unclear.
Brain-chemical imbalances: Neurotransmitter imbalances appear to play a key role in many mood disorders, including bipolar disorder.
Hormonal problems: Hormonal imbalances might trigger or cause bipolar disorder.
Environmental factors: Abuse, mental
stress, a "significant loss," or some other traumatic event may contribute to or trigger bipolar disorder.
One possibility is that some people with a genetic predisposition for bipolar disorder may not have noticeable symptoms until an environmental factor triggers a severe mood swing."