While the cause of bipolar disorder is not understood, a number of risk factors probably interact in the development of the disorder.
Genes
There is a strong genetic link in bipolar disorder, however, there is no single gene or set of genes responsible. It is thought that there are a number of genes involved in the inheritance of bipolar disorder, and that other personal, environmental and social factors also play a role.
Environmental and social factors
There is growing research into the possible influence of environmental factors, adverse life events (e.g., childhood abuse) and other types of stress, which are now thought to play a significant role.
Health-related factors
Bipolar disorder symptoms can also be related to certain medical conditions (e.g., a traumatic brain injury) or be triggered by substance use or some medications.