Changes in intracranial volume and cranial shape in modern Koreans over four decades

Objectives: This study investigated whether there was any secular change in cranial vault morphology among Koreans born between the 1930s and 1970s, a period of dramatic shift in Korea's socioeconomic conditions. Materials and methods: Using three-dimensional MRI volumetry, we obtained the intracranial volume (ICV) and craniometric measurements of 115 healthy Koreans: 58 individuals (32 males and 26 females) born in the 1930s (1926–1936) and 57 (28 males and 29 females) born in the 1970s (1972–1979). Results: The intracranial volume of males was 1502.3 ± 110.3 cm³ for the 1930s group and 1594.1 ± 99.5 cm³ for the 1970s group, and for females, it was 1336.0 ± 53.0 cm³ for the 1930s group and 1425.9 ± 79.6 cm³ for the 1970s group. On average, ICV increased by 94 cm³ in males and by 90 cm³ in females. Cranial measurements for the 1970s group were significantly larger than the 1930s group for both sexes except in female cranial length. Each measurement was significantly correlated with ICV [cranial height (R = 0.720), breadth (R = 0.706), and length (R = 0.531)]. The cephalic index decreased from 0.846 to 0.828 in males, indicating the cranium became narrower relative to the cranial length. In females, the cephalic index increased from 0.831 to 0.850. Sex and birthyear were marginally interrelated in cephalic indices. Discussion: From the 1930s to 1970s, the Korean Peninsula experienced important historical shifts, and we speculate that the consequent shift in socioeconomic status is the most likely factor responsible for Koreans’ cranial vault remodeling.