Association between affective temperaments and thalamic nuclei volumes

Affective temperaments are stable, biologically based traits that may represent subclinical manifestations or premorbid phenotypes of mood disorders. The thalamus is increasingly recognized as an active component of distributed neural networks involved in cognition, emotion, and behavioral regulation. We focused on the thalamus and conducted an exploratory analysis of the associations between affective temperaments and the volumes of thalamic nuclei in healthy participants.

This study included 43 healthy right-handed participants. Affective temperament was assessed using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire. T1-weighted structural magnetic resonance imaging data were acquired using a 3T scanner and processed with FreeSurfer version 7.1.1 to obtain the estimated total intracranial volume (eTIV) and the volumes of 52 thalamic regions, comprising 25 bilateral thalamic nuclei and the bilateral whole thalamus. The primary analyses were partial Spearman correlations adjusted for age, sex, and eTIV. Given that 52 thalamic regions and five affective temperaments were examined, Bonferroni correction was applied to control the family-wise error rate for multiple comparisons. Statistical significance was defined as a Bonferroni-corrected threshold of P < 0.00019 (0.05/[52 × 5]). Additional analyses adjusted for age, sex, and ipsilateral whole thalamus volume were performed as sensitivity analyses.

In the primary analysis, higher cyclothymic temperament scores were significantly associated with smaller left paratenial nucleus (Pt) volume (partial ρ = -0.57, P = 0.00015, 95% CI [-0.72, -0.36]). In the sensitivity analysis adjusting for age, sex, and left whole thalamus volume, the association was attenuated (partial ρ = -0.42, P = 0.007, 95% CI [-0.62, -0.17]) and did not meet the Bonferroni-corrected significance threshold. None of the other affective temperaments were significantly associated with left Pt volume. Several other associations of comparable magnitude were observed, but none met the corrected threshold.

Higher cyclothymic temperament scores were associated with smaller left Pt volume in the primary analysis. However, the association only narrowly met the corrected significance threshold and was attenuated in the sensitivity analysis. Thus, its regional specificity and statistical robustness remain uncertain, and replication in larger independent samples is warranted.