Mind Reading: Lab Testing for Mental Health Conditions

The idea of a simple, definitive laboratory test to diagnose mental health conditions is appealing—but currently out of reach. Instead of diagnostics for depression or blood tests for bipolar disorder, physicians usually rely on clinical signs and symptoms to identify and monitor their patients’ mental wellbeing. But that doesn’t mean the lab has no role to play in mental health; in fact, many psychiatric conditions require laboratory testing to identify or rule out potential physical causes or contributors.

“Lab tests are often performed before a patient enters psychiatric care because the symptoms or behaviors that are attracting attention are suspected of having an organic cause,” explains psychiatric specialist nurse Susan Schubert. “Healthcare providers try to rule those things out first—sometimes even if it’s a new episode of a previously diagnosed psychiatric illness.” As an example, she describes an urgent call to see a patient suspected of a mental health emergency. “We began to suspect an organic cause when we realized that she didn’t seem aware of us when we were on one side of her. She saw and spoke to my colleague, but didn’t look at me or seem to hear my questions and jumped in surprise when I moved to the other side of her bed.” Ultimately, Schubert’s team requested emergency medical care and diagnostics, which revealed Creutzfeldt-Jakob disease as the cause of the patient’s psychiatric symptoms—a rare occurrence, but a clear illustration of the value of diagnostic testing in mental health care.

Laboratory testing in the realm of mental health typically falls into two categories—standard workups and genetic testing.

Standard workups

Many physical conditions include symptoms that can mimic mental health concerns. For instance, hypothyroidism can lead to fatigue, cognitive dysfunction, low mood or mood cycling, and—in severe cases—even psychosis.¹ Conversely, excess thyroid hormone can cause anxiety, irritability, apathy, or emotional lability.² As a result, it’s common for practitioners to order complete blood counts, metabolic panels, and thyroid function tests when evaluating patients with nonspecific symptoms like fatigue, low mood, or changes in cognitive function. Similarly, vitamin and nutrient testing can reveal deficiencies that affect mood, memory, and behavior; meta-analyses have revealed links between abnormally low vitamin B levels and high-risk psychiatric episodes³ and between vitamin D deficiencies and major depression.⁴

In psychiatric emergency situations, medical providers often pursue toxicology screening. However, modern immunoassays, although rapid, may return false positive results due to cross-reactivity or false negatives due to poor sensitivity or highly specific detection of individual substances, rather than classes of drugs. Numerous studies have questioned the value of such screenings, ultimately concluding that their utility is limited and that not all clinicians fully understand the tests’ benefits and potential disadvantages before ordering.⁵

Before prescribing medication to help patients manage their mental health, many providers order kidney and liver function tests—sometimes to obtain a baseline in case a treatment causes abnormalities; sometimes to identify or quantify existing abnormalities that could affect the risks or pharmacokinetics of the treatment. To maximize return on investment, experts recommend avoiding tests for rare, unpredictable, or unpreventable conditions and focusing more intense screening efforts on patients with low socioeconomic status, in whom pre-existing conditions are more likely to have been overlooked.^6,7 Managing test utilization with these considerations in mind not only ensures that high-risk patients continue to be evaluated for preventable and treatable issues, but also increases the overall cost-effectiveness of laboratory testing in mental health care.

Genetic testing

The main application of genetic testing in psychiatry is pharmacogenomics (PGx): determining which treatments are likely to be most effective or least likely to cause side effects or adverse events. However, many institutions face barriers to the routine use of PGx testing—most commonly the lack of high-quality evidence for its utility, minimal physician education regarding its benefits and limitations, and the cost-effectiveness of implementing and maintaining a PGx testing program.^8,9 Labs can help overcome these barriers in several ways:

• • Collaborate to improve research and education around PGx. This includes working with policymakers, regulatory bodies, and other organizations to ensure that stakeholders understand the value of such testing, its potential pitfalls (and corresponding opportunities for further research), and the specific needs of their communities—for instance, considering the genetic background of the population in areas where non-European ancestry is common.

• • Participate in PGx research. This may include assisting with study design, determining the type and scale of testing, performing PGx testing, or even advocating for funding.

• Ensure that lab staff are educated in the basics of genetics, genomics, and PGx. If appropriate, extend that education to non-laboratory healthcare professionals by collaborating with clinicians, offering informal training, or providing or recommending resources. In some instances, patients may be hesitant to engage in PGx testing due to lack of understanding, ethical or cultural concerns, or misinformation; laboratorians can interact directly with patients to offer education, dispel misconceptions, and—after testing—explain the results and their implications.

But psychiatric PGx testing is still in its infancy. Although numerous tests have already been approved and international guidelines established, many experts have pointed out that genes affecting drug metabolism don’t necessarily correspond to clinical response,¹⁰ that treatment response involves multiple genes with minimal individual contributions,¹¹ and that decisions made on a pharmacological basis are likely to yield similar results to those made using PGx.¹²

Testing for genetic predispositions to psychiatric disorders faces similar challenges. The sheer number of contributing genes involved in most mental health conditions and the small scale of any individual gene’s influence means that it can be difficult to identify meaningful genes to test—and factors ranging from epigenetics to life experience can affect the nature and degree to which contributing genes are expressed.

Nonetheless, some mental health concerns are more testable than others. A recent report from the UK’s Royal College of Psychiatrists recommends genetic testing in specific patient populations, such as people with schizophrenia and a family history or co-occurring condition, children and adolescents whose mental health conditions present unusually, or people with signs of specific types of dementia or intellectual disability. The report also encourages further studies into mental health genetics, but recommends against certain tests, such as polygenic risk scores or epigenetic testing.¹³ Ultimately, most experts agree that molecular testing currently has valuable, but limited scope in mental health care¹⁴—but that ongoing research has the potential to change the way such conditions are prevented, predicted, diagnosed, and treated in the future.

References:

1. 1. Nuguru SP et al. Hypothyroidism and depression: a narrative review. Cureus. 2022;14(8):e28201. doi:10.7759/cureus.28201.

1. 1. Hage MP, Azar ST. The link between thyroid function and depression. J Thyroid Res. 2012;2012:590648. doi:10.1155/2012/590648.

1. 1. Tamune H et al. Efficient prediction of vitamin B deficiencies via machine-learning using routine blood test results in patients with intense psychiatric episode. Front Psychiatry. 2020;10:1029. doi:10.3389/fpsyt.2019.01029.

1. 1. Vellekkatt F, Menon V. Efficacy of vitamin D supplementation in major depression: a meta-analysis of randomized controlled trials. J Postgrad Med. 2019;65(2):74–80. doi:10.4103/jpgm.JPGM_571_17.

1. 1. Bahji A et al. Assessing the utility of drug screening in the emergency: a short report. BMJ Open Qual. 2018;7(4):e000414. doi:10.1136/bmjoq-2018-000414.

1. 1. Mago R. Before You Write That Prescription: Guidelines for Ordering Lab Tests. The Carlat Psychiatry Report. November 1, 2015. https://www.thecarlatreport.com/articles/2404-before-you-write-that-prescription-guidelines-for-ordering-lab-tests.

1. 1. The Carlat Psychiatry Report. Screening Labs for New Patients: Are They Useful? PsychCentral. August 26, 2013. https://psychcentral.com/pro/screening-labs-for-new-patients-are-they-useful.

1. 1. Virelli CR et al. Barriers to clinical adoption of pharmacogenomic testing in psychiatry: a critical analysis. Transl Psychiatry. 2021;11(1):509. doi:10.1038/s41398-021-01600-7.

1. 1. Pinzón-Espinosa J et al. Barriers to genetic testing in clinical psychiatry and ways to overcome them: from clinicians’ attitudes to sociocultural differences between patients across the globe. Transl Psychiatry. 2022;12(1):442. doi:10.1038/s41398-022-02203-6.

1. 1. Cohen BM, Zubenko GS. Gene testing to guide antidepressant treatment: Has its time arrived? Harvard Health Blog. October 19, 2019. https://www.health.harvard.edu/blog/gene-testing-to-guide-antidepressant-treatment-has-its-time-arrived-2019100917964.

1. 1. Zubenko GS et al. On the marketing and use of pharmacogenetic tests for psychiatric treatment. JAMA Psychiatry. 2018;75(8):769–770. doi:10.1001/jamapsychiatry.2018.0834.

1. 1. Macaluso M, Preskorn SH. Knowledge of the pharmacology of antidepressants and antipsychotics yields results comparable with pharmacogenetic testing. J Psychiatr Pract. 2018;24(6):416–419. doi:10.1097/PRA.0000000000000345.

1. 1. Royal College of Psychiatrists. College Report CR237: The role of genetic testing in mental health settings. October 2023. https://www.rcpsych.ac.uk/docs/default-source/improving-care/better-mh-policy/college-reports/College-report-CR237—Genetic-testing-in-mental-health-settings.pdf.

1. 1. Hoehe MR, Morris-Rosendahl DJ. The role of genetics and genomics in clinical psychiatry. Dialogues Clin Neurosci. 2018;20(3):169–177. doi:10.31887/DCNS.2018.20.3/mhoehe.