Lower Thyroid Hormone Levels a Red Flag for Elevated Suicide Risk?

Patients with comorbid anxiety and mood disorders who have reduced, albeit “normal,” serum levels of thyroid-stimulating hormone (TSH) may be at increased risk for suicidal ideation, new research suggests.

In a cross-sectional study, clinical data on diagnosis, medication use, and symptom scores were gathered, along with assessments of blood levels of thyroid axis hormones, in patients with both anxiety and mood disorders.

After investigators accounted for age, gender, symptoms, medication use, and other potential confounders, patients with suicidal ideation were 54% less likely to have higher TSH levels. There was no association found with other thyroid hormones.

Based on the results, the assessment of thyroid hormone levels “may be important for suicide prevention and might allow clinicians to evaluate the potential of the suicidal ideation risk in individuals with [anxiety and mood disorders],” co-investigator Vilma Liaugaudaite, PhD student, Neuroscience Institute of the Lithuanian University of Health Sciences, Palanga, and colleagues note.

The findings were presented at the 34th European College of Neuropsychopharmacology (ECNP) Congress.

“Complex Mechanism”

Liaugaudaite told Medscape Medical News that thyroid hormones are known to have a “profound” effect on mood and behavior.

Recent studies show “various degrees of hypothalamic-pituitary-thyroid axis dysregulation are associated with suicidal behavior” in patients with depression, she added.

Noting that disturbances in the serotonin system “constitute the most common biochemical abnormality associated with suicidal behavior,” Liaugaudaite said it is thought thyroid hormones “are involved in a complex compensatory mechanism to correct reduced central 5-hydroxytryptamine activity” via lower TSH levels.

In addition, hypersecretion of thyrotropin-releasing hormone, which stimulates the release of TSH, “has been considered a compensatory mechanism to maintain normal thyroid hormone secretion and normalize serotonin activity in depressed patients,” she said.

To investigate associations between thyroid axis hormones and suicidality in individuals with comorbid anxiety and mood disorders, the researchers assessed consecutive patients attending a stress disorders clinic.

Sociodemographic and clinical information was gathered, and patients completed the Mini International Neuropsychiatric Interview, the Patient Health Questionnaire-9 (PHQ-9), and the General Anxiety Disorder-7 (GAD-7) scale.

Fasting blood samples were also tested for free thyroxine (FT4), free triiodothyronine (FT3), and TSH levels.

Significant Association

Seventy-seven patients aged 18 to 73 years participated in the study. Of these, 59 were women. Suicidal ideation was identified in 42 participants. Serum FT4, FT3, and TSH levels were within the normal range.

There were no significant differences between patients with and without suicidal ideation in terms of age, gender, education, obesity, smoking, and medication use.

Suicidal ideation was associated with higher scores on the PHQ-9 (15.5 vs 13.3; P = .085), and with lower TSH levels (1.54 IU/L vs 2.04 IU/L; P = .092).

The association between serum TSH levels and suicidal ideation was significant after multivariate logistic regression analysis accounted for age, gender, PHQ-9 and GAD-7 scores, education, body mass index, smoking, and use of antidepressants, tranquilizers, mood stabilizers, and neuroleptics.

Specifically, patients with suicidal ideation were significantly less likely to have higher TSH levels than those without, at an odds ratio of 0.46 (P = .027).

There were no significant associations between serum FT4 and FT3 levels and suicidal ideation.

Interesting, but Preliminary

Commenting on the findings for Medscape Medical News, Sanjeev Sockalingam, MD, vice chair and professor of psychiatry at the University of Toronto, Ontario, Canada, said it is an “interesting study” because the literature on trying to identify individuals at risk for suicidal ideation or behaviors is “quite mixed, in terms of the results.”

However, it was a cross-sectional study with a relatively small sample size, and studies of this nature typically include patients with hypothyroidism “who end up having suicidal thoughts,” said Sockalingam, who was not involved with the research.

“I do wonder, given the sample size and patient population, if there may be other factors that may have been related to this,” he added.

Sockalingam noted that he would like to see more data on the medications the patients were taking, and he underlined that the thyroid levels were in the normal range, “so it’s a bit difficult to untangle what that means in terms of these subtle changes in thyroid levels.”

Robert Levitan, MD, Cameron Wilson Chair in Depression Research at the Centre for Addiction and Mental Health, Toronto, Ontario, Canada, also emphasized that the thyroid levels were in the normal range.

He commented to Medscape Medical News that it therefore “seems unlikely that there’s going to be some biological effect that’s going to affect the brain in a significant enough way” to influence suicidal ideation.

Levitan continued, “What’s probably happening is there’s some other clinical issue here that they just haven’t picked up on that’s leading in one direction to the suicidal ideation and perhaps affecting the TSH to some extent.”

Although the study is therefore “preliminary,” the findings are nevertheless “interesting,” he concluded.

The study received no funding. Liaugaudaite, Sockalingam, and Levitan have disclosed no relevant financial relationships.

34th European College of Neuropsychopharmacology (ECNP) Congress: Abstract P.0070. Presented October 2, 2021.

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