Nature vs. Nurture: What Causes Bipolar Disorder?

Bipolar disorder, previously known as manic depression, is a mental illness characterized by extreme mood swings that range from emotional highs (mania or hypomania) to emotional lows (depression). The cause of bipolar disorder is not yet fully understood, but it is believed that both nature and nurture play a role in its development.

Nature: Biological Factors

There is evidence to suggest that genetic factors play a role in the development of bipolar disorder. Studies of families with a history of bipolar disorder have found that the risk of developing the disorder is higher in relatives of people with the illness. According to the National Institute of Mental Health, children with one parent who has bipolar disorder have a 15-25% chance of developing the disorder themselves, and that risk increases to 50-75% if both parents have bipolar disorder.

In addition to genetic factors, there are also biological factors that may contribute to the development of bipolar disorder. These include imbalances in certain neurotransmitters like dopamine and serotonin, as well as abnormalities in brain structure and function.

Nurture: Environmental Factors

Environmental factors such as stressful life events, substance abuse, and sleep disruptions may trigger the onset of bipolar disorder in people who are genetically predisposed to the illness. Studies have shown that people with bipolar disorder are more likely to have experienced childhood trauma, such as physical or sexual abuse, or neglect.

Other environmental risk factors for bipolar disorder include:

– Having a family member with a mental illness
– Living in a stressful or chaotic environment
– Serious health problems, such as cancer or heart disease
– Substance abuse or addiction
– Medications that can trigger mania, such as antidepressants


The debate over nature vs. nurture in the development of bipolar disorder is ongoing, but research suggests that both biological and environmental factors play a role. While genes and brain structure likely contribute to an individual’s susceptibility to the disorder, environmental factors can trigger its onset. Further research is needed to fully understand the complex interplay between nature and nurture in the development of bipolar disorder.