Bipolar disorder can lead to extreme shifts in mood, activity levels, and energy.

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The condition affects approximately 2.8% of the adult population in the United States.

To diagnose bipolar disorder, a doctor may:

  • conduct an interview or ask questions about the person’s symptoms
  • perform a physical exam
  • order tests, which may include brain scans

Currently, doctors use brain scans and blood work to check for the presence of other conditions that may be causing similar symptoms to those of bipolar disorder.

Emerging evidence suggests that doctors may be able to use brain scans to help diagnose this condition in the future.

In general, doctors do not recommend brain scans to diagnose bipolar disorder.

According to the Depression and Bipolar Support Alliance, there are currently two reasons that a doctor may order a brain scan for a person with bipolar disorder.

The first reason is to determine if a condition such as a stroke or a tumor could be causing a person’s symptoms instead of bipolar disorder. However, this is rare.

The second reason is to be a part of research. Researchers are conducting studies to see whether or not there are identifiers within the brain that can help diagnose bipolar disorder. The results may help a doctor distinguish between bipolar disorder and major depressive disorder.

Several recent studies have helped uncover brain changes in people with bipolar disorder.

In a 2019 study, researchers found that amygdala activation and connectivity in the brain are different between people with bipolar disorder and major depressive disorder. This finding may help doctors distinguish between the two conditions.

In a study from 2018, researchers looked at MRI scans and visualizations to determine the differences between people with bipolar disorder and people in control groups.

They found that when a person with bipolar disorder was neither in a state of mania nor a state of depression, their brains responded in the same way as the brains of the people in the control group.

However, the researchers did find brain changes in people in a state of mania or depression. In particular, their visual cortices changed appearance, showing less activity than the brains of those in the control group.

The study suggests that changes in sensory areas of the brain may also indicate bipolar disorder.

In a recent review, researchers found that evidence across several studies indicates widespread patterns of subcortical volume, lower cortical thickness, and disrupted white matter integrity. They suggest that future research may help determine key markers and help with the diagnosis of bipolar disorder.

Researchers also looked at how both the structure and the processes of the brain looked using MRI in another study. They found that using both types of images may help better identify and diagnose bipolar disorder.

According to the National Alliance on Mental Illness, a person needs to have had at least one manic episode to meet the criteria for a diagnosis of bipolar disorder.

Diagnosis consists of a physical exam and mental health interview. Currently, blood tests and imaging can help rule out other conditions that can damage the brain.

Following an initial diagnosis, a doctor will typically refer a person to a mental health professional, such as a psychiatrist or psychologist. They can determine which type of bipolar disorder a person has.

The types of bipolar disorder include:

  • Bipolar I disorder: This is when a person has at least one manic episode and experiences both manic and depressive periods.
  • Bipolar II disorder: This means that a person shifts between depression and hypomanic episodes but never experiences a full manic episode.
  • Cyclothymic disorder: This occurs when a person experiences both mild depression and hypomanic episodes for at least 2 years.
  • “Other specified” and “unspecified”: This is when a person has mood elevations but does not fit the criteria for other bipolar types.

According to older research, diagnosing bipolar disorder is often difficult, and misdiagnosis is common.

The main reasons for misdiagnosis include:

  • lapses in history-taking
  • the presence of psychiatric or medical comorbidities
  • limitations in diagnostic criteria

Misdiagnosis using traditional methods of diagnosis makes research into how the brain looks when a person has bipolar disorder all the more important.

A person can talk with a doctor or mental health professional about the possibility of joining a clinical trial. Clinical trials can help both participants and researchers.

Resources are available online to help a person find a study to participate in. The National Institute on Mental Health have a resource to search for studies. A person could also visit ClinicalTrials.gov to find studies that they may be interested in.

Brain scans of people with bipolar disorder may have some differences or anomalies. Differences may be physical or show diminished or increased activity in the brain.

Currently, doctors do not use brain images to diagnose bipolar disorder. However, as research advances, more evidence may help doctors use MRI scans or other imaging technology to accurately diagnose bipolar disorder.