man getting blood test for bipolar disorder

For people who have bipolar disorder and other complex mental health concerns, receiving an accurate diagnosis for bipolar disorder is an essential step on the path toward appropriate treatment and improved quality of life – and a new study explores the possibility of diagnosing bipolar disorder using blood tests.

Unfortunately, bipolar disorder is often misdiagnosed as depression. This can lead to significant delays in treatment and other negative outcomes.

Mary L. Philips, MD, and David J. Kupfer, MD, addressed the challenges of accurately diagnosing bipolar disorder in a March 2018 report published in the journal Lancet. Among their findings:

  • Only about 20% of people with bipolar disorder who have a depressive episode receive an accurate diagnosis within 12 months of seeking treatment.
  • The delay between the onset of symptoms of bipolar disorder and an accurate diagnosis is between 5–10 years.

“Misdiagnosis of bipolar disorder type I or II as unipolar depression has many potentially deleterious consequences, including prescription of inappropriate drugs…and, ultimately, poor clinical and functional outcome and high healthcare costs,” the psychiatrists wrote.

The problem of using the wrong medications isn’t limited to a failure to alleviate the symptoms of bipolar disorder, they added. Certain antidepressants may actually trigger the onset of manic episodes, which can exacerbate symptom severity and increase distress.

Thankfully, recent research indicates clinicians may soon have more robusts tools to differentiate between bipolar disorder and depression.

The Difficulty of Diagnosing Bipolar Disorder

One of the reasons bipolar disorder can be so challenging to diagnose is that people with bipolar disorder often present a variety of symptoms.

Though informal references to bipolar disorder make it sound like it’s one disorder, there are actually three types:

Bipolar I:

As established in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the criteria for a diagnosis of bipolar I disorder is a manic episode. People with bipolar I disorder may also have major depressive episodes, but it’s not required for this diagnosis.

Bipolar II:

Individuals who have bipolar II disorder must have at least one hypomanic episode and at least one major depressive episode.

Cyclothymic disorder:

People who have cyclothymic disorder report hypomanic symptoms that don’t meet criteria for a full manic or hypomanic episode. They also experience depressive symptoms that don’t rise to the level of a major depressive episode.

Here’s more about the symptoms characteristic of the various forms of bipolar disorder:

  • Manic and hypomanic episodes include periods of excessive energy, heightened self-esteem, elevated motivation, and related symptoms. Manic episodes last for at least a week, while hypomanic episodes last a minimum of four days.
  • Major depressive episodes include diminished energy, pervasive sadness, low self-confidence, and little to no motivation. To meet the criteria for a major depressive episode, these symptoms must occur most days, most of the day, for at least two consecutive weeks.

During a manic or hypomanic episode – or while experiencing hypomanic symptoms – a person feels energetic and confident. They’re unlikely to seek professional care, because they believe they don’t need it.

Most of the time, if someone with bipolar disorder contacts a professional, it’s during a major depressive episode, or (in the case of cyclothymic disorder) when they’re directly affected by depressive symptoms.

Since the patient presents with symptoms consistent with depression, the assessing clinician may arrive at a diagnosis of major depressive disorder or persistent depressive disorder.

Complicating the matter further, when asked about their history, patients may not realize they’ve had manic episodes. They may believe times of elevated mood, attitude, and energy represent how they’re supposed to feel when they’re not experiencing depressive symptoms.

Identifying Biomarkers of Bipolar Disorder

A team of researchers from Cambridge University developed a blood test they believe can help clinicians more accurately diagnose bipolar disorder. The Cambridge report on this development appeared on the JAMA Psychiatry website in October 2023.

Features of the report included the following:

  • The researchers tested dried blood spot (DBS) samples submitted by 241 subjects recently diagnosed with major depressive disorder (MDD).
  • Additional evaluation, including the Composite International Diagnostic Interview (CIDI) revealed 67 of the subjects had bipolar disorder, not MDD.
  • Using a targeted mass spectrometry-based platform, researchers focused on 650 metabolites in participants’ blood samples.
  • The researchers found “a distinct profile of DBS metabolites” among the study subjects with bipolar disorder.

In an article on the Cambridge University website, Dr. Jacob Tomasik indicated clinicians should use both a blood test and an diagnostic tool such as the CIDI to accurately diagnose bipolar disorder. However, the blood test seemed to be especially significant from the patient perspective.

Here’s how he describes this interesting component of the data:

“We found that some patients preferred the biomarker test, because it was an objective result that they could see. Mental illness has a biological basis, and it’s important for patients to know it’s not in their mind. It’s an illness that affects the body like any other.”

In the same article, lead researcher Professor Sabine Bahn noted the benefits of identifying biomarkers of bipolar disorder may not be limited to making more accurate diagnoses:

“[The biomarkers] could also be used to identify potential drug targets for mood disorders, which could lead to better treatments.”

Using Biomarkers to Assess Risk & Determine Symptom Severity

Before the Cambridge study, another group of researchers explored blood analysis as a means of diagnosing bipolar disorder and other mental health conditions.

In April 2021, the journal Molecular Psychiatry published a study on a blood test that used RNA biomarkers to help diagnose and treat depression and bipolar disorder.

This study, led by Dr. Alexander B. Niculescu of Indiana University, followed 300 participants for four years. Niculescu’s team found that analysis of blood biomarkers could do more than determine the presence of a particular disorder. The team revealed biomarkers could also help clinicians identify:

  • Severity of depression
  • Risk for developing more severe symptoms in the future
  • Risk of developing bipolar disorder

These findings built on over a decade of prior research, which included using blood biomarkers to assess patients with a variety of other conditions, including pain, posttraumatic stress disorder (PTSD), Alzheimer’s disease, and suicide risk.

Here’s how Dr. Alexander B. Niculescu characterizes his findings:

“Blood biomarkers are emerging as important tools in disorders where subjective self-report by an individual, or a clinical impression of a health care professional, are not always reliable. These blood tests can open the door to precise, personalized matching with medications, and objective monitoring of response to treatment.”

The Promise of Precision Medicine in Mental Healthcare

As both the Cambridge University and IU researchers noted, using blood tests to identify biological signs of mental health disorders is a step toward using similar information to develop customized treatments that account for factors unique to each patient.

It’s called precision medicine.

Aspects of precision medicine, such as genetic testing and the identification of certain biomarkers, are already in use in cancer treatment. In the mental health field, experts refer to precision medicine as precision psychiatry.

A February 2023 article in the journal Frontiers in Neuroscience described precision psychiatry as follows:

  • An effort to “refine diagnostic assessment and interventions to make them more accurately reflect and respond to the health status of individuals”
  • An attempt to improve the assessment of prognoses and the selection of treatments “through better characterization of aspects of biology relevant to mental disorders”
  • The acknowledgement that “biology is a source not just of universal features of human physiology but also of individual variation.”

Many leading mental health experts and organizations promote and support the move toward precision psychiatry.

In May 2023, National Institute of Mental Health Director Joshua Gordon announced the launch of a federally funded initiative called Individually Measured Phenotypes to Advance Computational Translation in Mental Health (IMPACT-MH) to turn precision medicine from an objective to a reality within the mental health field.

Gordon writes:

“IMPACT-MH will enable the community of researchers, clinicians, and people who experience mental disorders to view mental illnesses in an entirely new way.”

Further, Gorden predicts precision psychiatry will allow treatment professionals to:

“…see the important individual differences that make each patient unique and that point the way to personalized, effective interventions.”

The takeaway from this new movement in mental health is that we’re moving toward consistent, reliable diagnosis and treatment of disorders that are traditionally difficult to diagnose accurately, which makes effective treatment challenging. Diagnosing bipolar disorder – and other mental health disorders – with objective criteria like blood/biomarkers may eliminate inaccurate diagnoses, thereby providing appropriate treatment to people in need in a more timely and effective manner.