Table of ContentsView AllTable of ContentsGenetic FactorsBrain StructureSocietal FactorsEnvironmental TriggersThe Diathesis-Stress ModelNext in Bipolar Disorder GuideTreating Bipolar Disorder

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Table of Contents

Genetic Factors

Brain Structure

Societal Factors

Environmental Triggers

The Diathesis-Stress Model

Next in Bipolar Disorder Guide

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Whether you can be born withbipolar disorderremains an unresolved question. Studies suggest a genetic component to this mental illness, but DNA isn’t the only reason people develop bipolar disorder. Most researchers agree that brain and environmental factors probably contribute as well.

1:47Watch Now: Understanding Bipolar Disorder Triggers

1:47

Watch Now: Understanding Bipolar Disorder Triggers

Considerable research in multiple families, adoption, and twin studies has focused on the question of bipolar disorder’s heritability—whether bipolar disorder can be inherited.

This is important for genetic theories because identical twins occur when one fertilized egg splits in two, meaning that they share the same genetic material. Fraternal twins, on the other hand, come from separate fertilized eggs, so their inherited genes can be different. There is overwhelming evidence that bipolar disorder can be inherited and that there is a genetic vulnerability to developing the illness.

In families of persons with bipolar disorder, first-degree relatives (parents, children, siblings) are more likely to have a mood disorder than the relatives of those who do not have bipolar disorder.Studies of twins indicate that if one identical twin has bipolar disorder, the likelihood that the other twin will have it has been estimated to be between 40% to 70%.In fraternal twins, the occurrence in both has been estimated at around 5% to 10% percent.

What Is the Stress-Vulnerability Model?

Brain Function

When it comes to figuring out exactly what is inherited, theneurotransmitter systemhas received a great deal of attention as a possible cause of bipolar disorder. A link exists between neurotransmitters and mood disorders, and drugs that alter these transmitters also treat mood disorders:

A low or high level of a specific neurotransmitter such asserotonin,norepinephrine, ordopamineare associated with mood disorders.Other studies indicate that an imbalance of these substances is the problem, i.e., that a specific level of a neurotransmitter is not as important as its amount in relation to the other neurotransmitters.Still, other studies have found evidence that a change in the sensitivity of the receptors on nerve cells may be involved.

In short, researchers are quite certain that the neurotransmitter system is at least part of the cause of bipolar disorder, but further research is still needed to define its exact role.

How stress triggers a bipolar episode is not fully understood, but scientists believe that the stress hormonecortisolplays a role. Stress increases the level of cortisol in the body, which causes alterations in how the brain functions and communicates. In fact, in people who have depression or bipolar disorder, cortisol levels may stay high even when stress isn’t present.

Stressful life events can range from a death in the family to the loss of a job, and from the birth of a child to a move.

Stress may stem from a variety of experiences. It cannot be precisely defined, since one person may perceive an event as extremely stressful while another individual encountering the same event may not experience much stress.

Stressful life events can lead to the onset of symptoms in those susceptible to bipolar disorder. However, once the disorder is triggered it may progress. Once the cycle begins, psychological and/or biological processes may take over and keep the illness active.

For Depressive Episodes

Once someone experiences bipolar disorder, small stresses may trigger depressive episodes.

Examples of bipolardepressive episodetriggers include:

For Manic Episodes

While triggers for manic and depressive episodes can be the same, there are some that are specific to manic or hypomanic episodes. According to a 2012 study in theJournal of Affective Disorders, unique triggers ofmanic or hypomanic episodesinclude:

In addition, the postpartum period and the use of an antidepressant, like anSSRI, may also trigger a manic or hypomanic episode.

When we look for the cause of bipolar disorder, the best explanation according to research published in 2015 is what is termed the “Diathesis-Stress Model.”

The worddiathesis, in simplified terms, refers to a physical condition that makes a person more susceptible than usual to certain diseases. Thus the Diathesis-Stress Model says that each person inherits certain physical vulnerabilities to problems that may or may not appear depending on what stresses occur in their life.

So the bottom line is that if you have bipolar disorder, you were likely born with the possibility of developing this disorder and something in your life triggered it. However, scientists could refine that theory tomorrow. The one sure thing is that they won’t give up looking for answers.

Treating Bipolar Disorder

7 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institute of Mental Health.Bipolar Disorder.Gordovez FJA, McMahon FJ.The genetics of bipolar disorder.Mol Psychiatry. 2020;25(3):544-559.Magioncalda P, Martino M.A unified model of the pathophysiology of bipolar disorder.Mol Psychiatry. 2022;27(1):202-211.van den Berg MT, Wester VL, Vreeker A, et al.Higher cortisol levels may proceed a manic episode and are related to disease severity in patients with bipolar disorder.Psychoneuroendocrinology. 2020;119:104658. doi:10.1016/j.psyneuen.2020.104658National Institute of Mental Health.Depression.Rodrigues Cordeiro C, Côrte-Real BR, Saraiva R, Frey BN, Kapczinski F, de Azevedo Cardoso T.Triggers for acute mood episodes in bipolar disorder: A systematic review.Journal of Psychiatric Research. 2023;161:237-260. doi:10.1016/j.jpsychires.2023.03.008Kemner SM, van Haren NE, Bootsman F, et al.The influence of life events on first and recurrent admissions in bipolar disorder.Int J Bipolar Disord. 2015;3:6. Published 2015 Feb 25. doi:10.1186/s40345-015-0022-4Additional ReadingAkiskal HS. Mood disorders: Clinical features. In BJ Sadock et al., eds., Kaplan and Sadock’s Comprehensive Textbook of Psychiatry, 9th ed., vol. 1, pp. 1693-1733. Philadelphia: Lippincott Williams and Wilkins (2009).

7 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institute of Mental Health.Bipolar Disorder.Gordovez FJA, McMahon FJ.The genetics of bipolar disorder.Mol Psychiatry. 2020;25(3):544-559.Magioncalda P, Martino M.A unified model of the pathophysiology of bipolar disorder.Mol Psychiatry. 2022;27(1):202-211.van den Berg MT, Wester VL, Vreeker A, et al.Higher cortisol levels may proceed a manic episode and are related to disease severity in patients with bipolar disorder.Psychoneuroendocrinology. 2020;119:104658. doi:10.1016/j.psyneuen.2020.104658National Institute of Mental Health.Depression.Rodrigues Cordeiro C, Côrte-Real BR, Saraiva R, Frey BN, Kapczinski F, de Azevedo Cardoso T.Triggers for acute mood episodes in bipolar disorder: A systematic review.Journal of Psychiatric Research. 2023;161:237-260. doi:10.1016/j.jpsychires.2023.03.008Kemner SM, van Haren NE, Bootsman F, et al.The influence of life events on first and recurrent admissions in bipolar disorder.Int J Bipolar Disord. 2015;3:6. Published 2015 Feb 25. doi:10.1186/s40345-015-0022-4Additional ReadingAkiskal HS. Mood disorders: Clinical features. In BJ Sadock et al., eds., Kaplan and Sadock’s Comprehensive Textbook of Psychiatry, 9th ed., vol. 1, pp. 1693-1733. Philadelphia: Lippincott Williams and Wilkins (2009).

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Institute of Mental Health.Bipolar Disorder.Gordovez FJA, McMahon FJ.The genetics of bipolar disorder.Mol Psychiatry. 2020;25(3):544-559.Magioncalda P, Martino M.A unified model of the pathophysiology of bipolar disorder.Mol Psychiatry. 2022;27(1):202-211.van den Berg MT, Wester VL, Vreeker A, et al.Higher cortisol levels may proceed a manic episode and are related to disease severity in patients with bipolar disorder.Psychoneuroendocrinology. 2020;119:104658. doi:10.1016/j.psyneuen.2020.104658National Institute of Mental Health.Depression.Rodrigues Cordeiro C, Côrte-Real BR, Saraiva R, Frey BN, Kapczinski F, de Azevedo Cardoso T.Triggers for acute mood episodes in bipolar disorder: A systematic review.Journal of Psychiatric Research. 2023;161:237-260. doi:10.1016/j.jpsychires.2023.03.008Kemner SM, van Haren NE, Bootsman F, et al.The influence of life events on first and recurrent admissions in bipolar disorder.Int J Bipolar Disord. 2015;3:6. Published 2015 Feb 25. doi:10.1186/s40345-015-0022-4

National Institute of Mental Health.Bipolar Disorder.

Gordovez FJA, McMahon FJ.The genetics of bipolar disorder.Mol Psychiatry. 2020;25(3):544-559.

Magioncalda P, Martino M.A unified model of the pathophysiology of bipolar disorder.Mol Psychiatry. 2022;27(1):202-211.

van den Berg MT, Wester VL, Vreeker A, et al.Higher cortisol levels may proceed a manic episode and are related to disease severity in patients with bipolar disorder.Psychoneuroendocrinology. 2020;119:104658. doi:10.1016/j.psyneuen.2020.104658

National Institute of Mental Health.Depression.

Rodrigues Cordeiro C, Côrte-Real BR, Saraiva R, Frey BN, Kapczinski F, de Azevedo Cardoso T.Triggers for acute mood episodes in bipolar disorder: A systematic review.Journal of Psychiatric Research. 2023;161:237-260. doi:10.1016/j.jpsychires.2023.03.008

Kemner SM, van Haren NE, Bootsman F, et al.The influence of life events on first and recurrent admissions in bipolar disorder.Int J Bipolar Disord. 2015;3:6. Published 2015 Feb 25. doi:10.1186/s40345-015-0022-4

Akiskal HS. Mood disorders: Clinical features. In BJ Sadock et al., eds., Kaplan and Sadock’s Comprehensive Textbook of Psychiatry, 9th ed., vol. 1, pp. 1693-1733. Philadelphia: Lippincott Williams and Wilkins (2009).

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