The exact inheritance pattern of bipolar is unclear, but it is likely that variations in many genes combine to increase a person's risk. Some environmental factors also play a role in triggering its symptoms.
The National Institute of Mental Health estimate that 2.8 percent of adults in the United States experience bipolar disorder in any given year. They also say that 4.4 percent of people will experience it at some point during their life.
In this article, we look at the genetic and nongenetic factors that may cause bipolar disorder, as well as some potential treatments for the condition.
Genetics and bipolar disorder
A genetic predisposition to bipolar disorder may not be enough to trigger its development.
People are more likely to develop bipolar disorder if they have a close relative with the condition.
Some research suggests that the lifetime risk of bipolar disorder in relatives of someone with the condition is 5–10 percent for a close relative and 40–70 percent for a twin.
However, scientists do not fully understand the role that genes play in bipolar disorder.
According to the National Institutes of Health (NIH), some studies indicate that irregularities in many genes combine to increase a person's risk. The exact way that this occurs remains unclear.
It is likely that just having a genetic predisposition to the disorder is not enough to trigger its development. Environmental factors may also be necessary to trigger symptoms in people with the relevant gene variations.
It is also important to note that just because someone is at greater risk of having bipolar disorder, it does not mean that they will go on to develop it.
Research suggests that the majority of people with a genetic risk are healthy, and most people with a relative who has bipolar disorder do not have the condition themselves.
Other causes and risk factors
Along with genetics, there are some environmental factors that appear to play a part in triggering bipolar disorder in susceptible people. These include:
- Periods of high stress: Examples of stressful events that could trigger bipolar symptoms include a death in the family or being a survivor of rape, abuse, or another traumatic experience.
- A traumatic head injury: Concussion or other types of brain injury may cause symptom onset.
- Alcohol or drug misuse: Substance misuse is common among those with bipolar disorder, and the conditions may trigger each other in some cases. Drinking alcohol and using drugs can worsen symptoms of both mania and depression.
- Childbirth: Some research suggests that childbirth has links to first-time psychiatric disorders, such as bipolar disorder, in new mothers.
Types of bipolar disorder and their symptoms
There are four subtypes of bipolar disorder, each with similar symptoms.
However, the occurrence, duration, and intensity of the symptoms can determine which subtype a person has.
Types of bipolar disorder include:
- Bipolar 1 disorder: This causes manic episodes lasting 1 week or more, or severe mania requiring hospitalization. If it occurs, a major depressive episode may last 2 weeks or more. A manic episode is all that is necessary to diagnose bipolar 1, however.
- Bipolar 2 disorder: This type is similar to bipolar 1 but involves a less intense form of mania called hypomania. A person with bipolar 2 must have a major depressive episode lasting 2 weeks or more preceding or following a hypomanic episode.
- Cyclothymic disorder: This type causes symptoms of hypomania and depression for 2 years or more, but they do not fit the criteria for truly manic or depressive episodes.
- Other types: These may involve bipolar disorder symptoms that do not fit into any of the other categories.
Symptoms of mania and hypomania
During manic episodes, which can cause extreme "highs" in mood, people may experience:
- a lower need for sleep
- a desire to engage in reckless behaviors such as using drugs or consuming alcohol
- difficulty concentrating or making decisions
- high energy levels and restlessness
- high self-esteem
- intense enthusiasm
- racing thoughts
Hypomania symptoms are similar to those of mania, but they are less intense.
Symptoms of depression
Depressive symptoms, lasting for 2 weeks or more, include:
- changes in appetite and sleep habits
- fatigue and low energy
- feelings of sadness or hopelessness
- an inability to concentrate or make decisions
- loss of interest in things the person once enjoyed
- low self-esteem
- oversleeping or not getting enough sleep
- suicidal thoughts or behaviors
Around 50 percent of people with bipolar disorder also experience symptoms of psychosis, such as hallucinations and delusions. These cause people to imagine things that are not happening, or to maintain false beliefs.
Other symptoms include anxiety and substance misuse.
Though bipolar disorder is a long-term condition, most people can manage their symptoms and improve their quality of life if they follow a treatment plan.
Treatment options include:
People with bipolar will need to take anti-anxiety medications or antipsychotic drugs.
Lithium, a mood stabilizer, is a common drug treatment for bipolar. Research suggests that it can help prevent relapses long-term.
Many people with bipolar will need to take alternative or additional medicines, such as:
It is up to the individual's doctor to determine whether or not they should take a specific medication. However, they do take the person's unique circumstances into consideration when they make a decision.
Psychotherapy can be beneficial for people with bipolar disorder. It can help people:
- recognize changes in their thoughts, behaviors, and mood
- regulate their emotions
- address unhelpful thought patterns
- establish routines
- learn new coping skills
- manage stress
- communicate with family members and other people more generally
Most people with bipolar may need to make lifestyle modifications to reduce the occurrence or severity of manic or depressive symptoms.
Some such changes include:
- not using drugs or alcohol
- eating a healthful diet
- exercising regularly
- establishing a sleep routine
- keeping a mood diary
- reducing stress through meditation, yoga, and deep breathing exercises
- seeking support
- staying up to date on bipolar treatments
Most experts believe that there is a genetic component to bipolar disorder, but they do not fully understand the specifics. They also think that these genetic variations must interact with environmental factors to trigger symptoms.
People with a close relative who has bipolar are at a higher risk of developing the condition, though being at risk does not mean that someone will definitely develop it.
People with any concerns that they or a family member are showing symptoms of bipolar disorder should see their doctor.
Many treatments exist to help people manage their symptoms and maintain a relatively good quality of life.