Significant association
Suicidal ideation was identified in 42 participants. Serum FT4, FT3, and TSH levels were within the normal range.
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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, Sanjeev Sockalingam, MD, vice chair and professor of psychiatry at the University of Toronto, 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 Dr. 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.
Dr. 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, also emphasized that the thyroid levels were in the normal range.
He commented 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.
Dr. 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. Ms. Liaugaudaite, Dr. Sockalingam, and Dr. Levitan have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.