What are the chances of bipolar disorder being passed on if it runs in your family?

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Genetics affect whether a person might develop bipolar disorder, a highly treatable mental health condition affecting about 2.8% of adults in the United States.

But while genes are important, your odds of inheriting bipolar disorder still depend on numerous environmental and behavioral factors.

So even though your risk of developing bipolar disorder could be higher if your parent or sibling has it, there’s still a good chance you won’t have bipolar disorder without other specific factors present.

Researchers have established that bipolar disorder has a genetic component. Based on twin studies, the chances of bipolar disorder being passed on is estimated to be around 60–80%.

This means that if you have a first degree relative (a parent or sibling) with bipolar disorder, your chances of developing it is about 10 times greater than those in the general population (0.5–1.5%).

So, if your father or sister lives with bipolar disorder, your individual risk is about 5–10%. But even if you have an identical twin with bipolar disorder — a person with whom you’d share 100% of your genes — your chances are still only about 50%.

According to a 2016 study, the genetic risk appears to be similar regardless of whether it comes from the mother’s or father’s side of the family.

But even though this mental health condition can be inherited, many people with bipolar disorder are isolated cases and do not have a family history of the illness.

It’s actually considered somewhat rare for bipolar disorder to affect multiple members of a family over several generations.

Are you born with bipolar disorder?

Babies aren’t born with symptoms of bipolar disorder. But — someone with a genetic risk is born carrying the genes that may increase their chances of developing the condition later in life.

However, many other factors besides heredity and genes play a role in whether these genes will be triggered, causing the disorder to develop.

It’s rare for symptoms of bipolar disorder to begin in childhood. For most people with bipolar disorder, symptoms start to appear in late adolescence or early adulthood.

Bipolar disorder is not caused by a single gene. Rather, many gene variants and factors are involved in the development of bipolar disorder for someone who has a family history.

Other environmental factors also play a role in triggering the onset of bipolar disorder in people with a genetic risk, but appear to contribute to a lesser degree.

In one gene study, researchers evaluated the family histories of people with bipolar I disorder to see how often the disorder appeared.

In total, they looked at 156 participants with bipolar disorder (65 women and 91 men) and their family members:

  • Among 57 participants, bipolar disorder was detected in a first degree relative: parents, siblings, and children.
  • Among 22 people, the condition was detected in a second degree relative: grandparents, aunts and uncles, or neices and nephews.
  • In 14 participants, it was detected in third degree relatives and beyond: cousins, great grandparents, and great uncles and aunts.

Similar results appeared regardless of whether the genetic risk came from the mother’s or father’s side of the family.

Evidence suggests that people with a family history of bipolar disorder may be more likely to experience:

Is bipolar disorder a single condition?

Rather than just being one disorder, some experts have proposed that bipolar disorder is a group of related mood disorders, sometimes called “bipolar spectrum disorders.”

Since symptoms of bipolar disorder overlap with many other conditions and experiences — such as side effects of using certain drugs — it’s not uncommon for people to be misdiagnosed or to have several diagnoses over a lifetime.

So while bipolar disorder tends to follow a typical disease course of intense shifts in mood and energy, individual symptoms vary widely and don’t fit neatly into one box.

For some people living with bipolar disorder, low mood can be the core symptom, while in others, it may be an elevated mood with excessive energy.

About half of people diagnosed with bipolar disorder are likely to experience psychosis.

Research suggests that 82.9% of people with bipolar disorder may experience more severe symptoms of the condition, the highest rate among all mood disorders.

According to the data, the more severe bipolar disorder symptoms may cause “serious impairment,” characterized as intense shifts in mood, energy, and activity levels affecting a person’s ability to perform everyday tasks.

Bipolar disorder appears to share a genetic link with related mental health conditions. This means that other treatable conditions may also develop in a person with bipolar disorder.

Conditions that can sometimes co-occur with bipolar disorder include:

Research suggests that relatives of people with bipolar disorder could be more likely to develop depression than bipolar disorder, illustrating a genetic component that goes beyond diagnostic categories.

Research in 2014 suggests bipolar disorder also appears to share a genetic relationship with schizophrenia and autism.

While schizoaffective disorder has been studied less, there’s some evidence that it also shares a family overlap with both schizophrenia and bipolar disorder.

The human genome and bipolar disorder

In a large genome-wide association study, researchers have identified 64 regions of the human genome that may increase someone’s chances of developing bipolar disorder. This is more than twice the number previously known.

For the study, an international team of researchers and scientists looked for common genetic markers in people with bipolar disorder.

They scanned more than 7.5 million common DNA variations in nearly 415,000 people — more than 40,000 were diagnosed with bipolar disorder.

Overall, they identified 64 regions of the genome that may increase someone’s chances of developing the condition. These included DNA variations involved in brain cell communication and calcium signaling.

The study’s findings also suggested that:

  • Sleep habits as well as alcohol and substance use influence bipolar disorder development.
  • There are genetically distinct bipolar disorder subtypes.
  • Genetic overlap may exist between bipolar disorder and other mental health conditions, such as schizophrenia and autism.
  • Bipolar I disorder has a strong genetic similarity with schizophrenia, but bipolar II disorder is more genetically similar to depression.

Although there’s a genetic component to developing bipolar disorder, other environmental and behavioral factors need to be present to trigger symptoms of this mental health condition.

At-risk social demographics

Some research suggests that certain demographics may carry a higher risk of developing bipolar disorder, including people who are:

  • living in under-resourced communities
  • unemployed
  • unmarried

However, it may be possible that these groups’ circumstances could be due to the social disruption that’s sometimes caused by managing bipolar disorder.

Conversely, the same study suggests that opposite demographics may have a greater chance of developing bipolar disorder. This includes people with a higher:

  • socioeconomic status
  • occupational level
  • creativity

This is contrary to findings on demographics at risk of developing depression and schizophrenia.

People living in urban environments may also have a higher chance of developing bipolar disorder with psychosis, according to the study.

However, research has found no association between urban residence and bipolar disorder without psychosis. This may suggest that living in a city could be a risk factor of developing psychosis, rather than bipolar disorder.

Other factors associated with bipolar disorder include:

  • trauma
  • high levels of stress
  • substance or alcohol use
  • sleep deprivation
  • a concussion or traumatic head injury
  • inflammation
  • infection

If you’re currently living with bipolar disorder, you’re not alone. Bipolar disorder is a manageable mental health condition with many treatment options.

Managing the symptoms and mood changes associated with bipolar disorder can help you feel better.

Most people with bipolar disorder need a combination of treatments, including:

For more information on seeking support for bipolar disorder, visit the Depression and Bipolar Support Alliance.