Association of Subclinical Hypothyroidism with Suicide Attempts in Early- versus Late-Onset Major Depressive Disorder

Previous studies have associated major depressive disorder (MDD) with thyroid function. However, the relationship between subclinical hypothyroidism (SCH) and suicide attempts (SAs) in patients with MDD different ages at onset remains unclear. We aimed to investigate the association between SCH and SAs in patients with MDD different ages at onset.

We categorized 1,708 patients with MDD into early- (EOG, 18-44 years) and late-onset (LOG, 45-60 years) groups. The Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), and the positive sub-scale of the Positive and Negative Syndrome Scale (PS-PANSS) were utilized to assess patients' emotion status and psychotic symptoms. Thyroid stimulating hormone (TSH), free tri-iodothyronine (FT3), and free thyroxine (FT4) were examined.

Compared with the EOG, the LOG had a higher proportion of females, higher marriage rate, lower education level, longer disease duration, higher HAMD, HAMA and PS-PANSS scores, higher TSH, lower FT3, and higher proportion of SCH. In the EOG, compared with those without SAs, those with SAs had a longer disease duration, shorter education, higher HAMD, HAMA, and PS-PANSS scores, higher TSH levels, accompanied by a higher incidence of SCH. While, in the LOG, compared with those without SAs, those with SAs had higher HAMD, HAMA, and PS-PANSS scores and higher TSH levels but no significant difference in the incidence of SCH. The risk factors for SAs in the EOG included disease duration (OR = 1.038, 95% CI 1.001-1.077), HAMD (OR = 1.122 95% CI 1.036-1.214), HAMA (OR = 1.302, 95% CI 1.217-1.392), PS-PANSS (OR = 0.954, 95% CI 0.912-0.997), and TSH level (OR = 1.224, 95% CI 1.143-1.311), while in the LOG encompassed HAMA (OR = 1.213, 95% CI 1.096-1.343) and TSH levels (OR = 1.140, 95% CI 1.028-1.264).

Elevated TSH levels and greater anxiety severity were associated with SAs in first-episode, drug-naïve patients with MDD, and correlates of SAs appeared to differ between early- and late-onset groups.