J Korean Soc Biol Ther Psychiatry.  2022 Feb;28(1):40-48.

Digit Ratio (2D:4D) and Subcortical Gray Matter Volumes in the Healthy Elderly *

• Park JM
• Lee YM
• Lee K
• Jeong HJ
• Lee BD
• Moon E
• Suh H
• Kim K

Abstract

Objectives
：This study was aimed to investigate whether 1) sexual dimorphism in subcortical gray matter volumes (GMV) and the length ratio between the second and fourth digits (2D:4D) would be found and 2) 2D:4D would have associated with subcortical GMV in healthy elderly people.
Methods
：Sixty-two females aged 70.3±6.3 (mean±SD) years and 23 males aged 70.4±4.9 years were recruited from the Dementia Clinic in the Pusan National University Hospital. The subjects with the clinical dementia rating scale-sum of boxes (CDR-SB) total score greater than 2.0, any psychiatric or neurological disease, or any pathologic lesion on brain MRI other than micro-angiopathy were excluded. The 2D:4D of the left and right hands were measured 3 times each. Volumetric segmentation of T1-weighted MRI scans was done by Freesurfer software (v7.1.1.1).
Results
：2D:4Ds of males were smaller than those of females significantly on repeated measures ANOVA. The males’ thalamus, putamen, hippocampus in both hemispheres and the right amygdala were larger than females’. These differences were not significant after controlling for age, education and total intracranial volume (ICV). In the females, the left 2D:4D was negatively correlated with the left hippocampal volume. In the males, 2D:4D was positively correlated with the volumes of ipsilateral or contralateral thalamus, hippocampus, amygdala and accumbens. These correlations were not significant after Bonferroni’s correction, except for the right accumbens.
Conclusions
：Sexual dimorphism of 2D:4D is preserved in healthy elderly people. There is a significant correlation between the right 2D:4D and GMV of the accumbens in males.

Keyword

Digit ratios; Sexual dimorphism; Subcortical gray; Elderly