Bipolar disorder is a complex mental health condition that doesn’t have a single cause. Instead, it results from a combination of genetic, neurological, environmental, and lifestyle-related factors. According to Talkspace, understanding these root causes is essential for both early intervention and effective treatment.
This article explores the most common risk factors and current scientific understanding of what causes bipolar disorder.
Genetic Risk Factors
One of the most well-documented causes of bipolar disorder is genetic inheritance. If you have a first-degree relative (such as a parent or sibling) with bipolar disorder, your risk is significantly higher.
A major 2025 study by the National Institute of Mental Health (NIMH) identified nearly 300 genetic markers linked to bipolar disorder, including 36 critical genes that overlap with other mental health conditions such as schizophrenia and major depressive disorder. While no single gene causes bipolar disorder outright, this research confirms that bipolar is highly heritable.
Brain Structure & Chemistry
Neuroimaging studies have revealed structural and functional differences in the brains of individuals with bipolar disorder. Abnormalities have been found in the:
Prefrontal cortex (responsible for decision-making)
Amygdala (regulates emotion)
Hippocampus (involved in memory and mood regulation)
These regions are often linked to mood swings and emotional dysregulation. Chemical imbalances—particularly in glutamate, dopamine, and serotonin—also play a role in manic and depressive episodes.
Epigenetics and Gene Regulation
Beyond genetics, epigenetic changes may explain why some people develop bipolar disorder while others with similar genetic profiles do not. Epigenetics involves changes in gene expression without altering the DNA sequence itself.
Factors like chronic stress, diet, and trauma can cause gene modifications (such as methylation), particularly affecting genes involved in:
Dopamine regulation
Serotonin transport
Brain-derived neurotrophic factor (BDNF)
Circadian rhythms
These changes can influence brain development and emotional processing over time.
Environmental Triggers & Life Events
According to Verywell Health, life experiences and environmental stressors are often the spark that triggers bipolar symptoms in genetically predisposed individuals.
Common triggers include:
Childhood trauma (emotional, physical, or sexual abuse)
Loss of a loved one
Relationship breakdowns
Financial hardship
Major life transitions (e.g. moving, divorce)
Substance use—such as alcohol, cannabis, or stimulant misuse—can also trigger or worsen mood episodes.
Medical Conditions & Secondary Bipolar Disorder
Sometimes, symptoms of bipolar disorder arise as a result of underlying medical conditions, medications, or neurological issues. This is known as secondary bipolar disorder.
According to the Mayo Clinic, possible causes include:
Hyperthyroidism
Multiple sclerosis
Cushing’s disease
Stroke
Certain antidepressants or steroids
A thorough medical evaluation is essential when diagnosing bipolar symptoms for the first time.
Inflammation and Autoimmune Links
A growing body of evidence points to the role of inflammation and autoimmune responses in the development of bipolar disorder. A UK-based study reported by The Guardian found that people with autoimmune diseases—like lupus or rheumatoid arthritis—are nearly twice as likely to develop bipolar or related mood disorders.
While research is still ongoing, this link suggests that inflammation in the body may influence brain function and mood regulation more than previously understood.
Hormonal Changes and Life Stages
For women, hormonal transitions—particularly around perimenopause—can contribute to the onset or worsening of bipolar symptoms. A UK study found a 100% increase in manic episodes and a 30% increase in depressive symptoms among women during perimenopause, compared to earlier years.
This highlights the importance of considering hormonal shifts when diagnosing and managing mood disorders.
Summary of Contributing Factors
Genetics: Inherited vulnerability from parents or close relatives
Brain chemistry: Differences in emotional processing regions of the brain
Epigenetics: Environmental triggers affecting gene expression
Trauma and stress: Can initiate or exacerbate mood episodes
Substance misuse: Can worsen or trigger symptoms
Medical conditions: May cause bipolar-like symptoms (secondary bipolar disorder)
Autoimmune conditions and inflammation: Linked to higher bipolar risk
Hormonal shifts: Especially during perimenopause in women
Final Thoughts
Understanding the causes of bipolar disorder is crucial for early diagnosis, treatment, and support. While genetics may lay the foundation, it is the combination of life experiences, biological changes, and environmental factors that determines whether the condition develops and how it progresses.
At Hope-FX, we’re committed to raising awareness, breaking stigma, and supporting individuals living with bipolar disorder. If you or someone you know is struggling, don’t hesitate to reach out.