Patients with anxiety and comorbid 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 collected, 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 thoughts were 54% less likely to have rates higher TSH. No association was found with other thyroid hormones.
According to the findings, assessment of thyroid hormone levels “may be important for suicide prevention and may allow clinicians to assess the risk potential for suicidal ideation in people with [anxiety and mood disorders]notes co-researcher Vilma Liaugaudaite, PhD student, Institute of Neuroscience, Lithuanian University of Health Sciences, Palanga, and colleagues.
The results were presented at the 34th Congress of the European College of Neuropsychopharmacology (ECNP).
Liaugaudait said Medscape Medical News that thyroid hormones are known to have a “profound” effect on mood and behavior.
Recent studies show that “various degrees of dysregulation of the hypothalamic-pituitary-thyroid axis are associated with suicidal behavior” in patients with depression, she added.
Noting that disturbances of the serotonergic system “constitute the most common biochemical abnormality associated with suicidal behavior,” Liaugaudaite said that thyroid hormones “are thought to be involved in a complex compensatory mechanism to correct reduced activity of the central 5-hydroxytryptamine” via lower TSH levels.
In addition, hypersecretion of thyrotropin-releasing hormone, which stimulates TSH release, “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 people with anxiety and comorbid mood disorders, the researchers evaluated consecutive patients attending a stress disorder clinic.
Sociodemographic and clinical information was collected and patients completed the International Neuropsychiatric Mini Interview, Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder Scale-7 (GAD-7).
Fasting blood samples were also tested for free thyroxine (FT4), free triiodothyronine (FT3), and TSH levels.
Seventy-seven patients between the ages of 18 and 73 participated in the study. Among them, 59 were women. Suicidal thoughts were identified in 42 participants. Serum levels of FT4, FT3 and TSH 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 status and drug use.
Suicidal ideation was associated with higher PHQ-9 scores (15.5 versus 13.3; P = 0.085), and with lower TSH levels (1.54 IU/L vs 2.04 IU/L; P = 0.092).
The association between serum TSH levels and suicidal ideation was significant after a multivariate logistic regression analysis controlling for age, sex, PHQ-9 and GAD-7 scores, education, body mass index, smoking, and use of antidepressants, tranquilizers, mood stabilizers, and neuroleptics.
Specifically, patients with suicidal thoughts were significantly less likely to have higher TSH levels than those without, with an odds ratio of 0.46 (P = 0.027).
There was no significant association between serum FT4 and FT3 levels and suicidal ideation.
Interesting, but preliminary
Commenting on the findings of Medscape Medical News, Sanjeev Sockalingam, MD, vice president and professor of psychiatry at the University of Toronto, Ontario, Canada, said it was an “interesting study” because the literature on trying to identify people with risk of suicidal ideation or behavior is “pretty mixed, in terms of outcomes.”
However, this 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 does not did not participate in the research.
“I wonder, given the sample size and the patient population, if there may be other factors that could have been linked to this,” he added.
Sockalingam noted that he would like to see more data on the medications the patients were taking, and he pointed out that the thyroid levels were within the normal range, “so it’s a bit difficult to sort out what that means in terms of of these subtle changes in thyroid levels.”
Robert Levitan, MD, Cameron Wilson Research Chair in Depression at the Center for Addiction and Mental Health, Toronto, Ontario, Canada, also pointed out that thyroid levels were within the normal range.
He commented to Medscape Medical News that it therefore “seems unlikely that there is a biological effect that will affect the brain significantly enough” to influence suicidal ideation.
Levitan continued, “What’s probably going on is there’s another clinical issue here that they just haven’t picked up on, which leads in a direction to suicidal ideation and possibly affects TSH to some extent.”
Although the study is therefore “preliminary”, the results are nevertheless “interesting”, he concluded.
The study received no funding. Liaugaudaite, Sockalingam and Levitan disclosed no relevant financial relationship.
34th Congress of the European College of Neuropsychopharmacology (ECNP): abstract P.0070. Presented October 2, 2021.