Aging of the cingulum in the human brain: Preliminary study of a diffusion tensor imaging study.

The cingulum, a major structure of the limbic system, is closely associated with memory function. In the current study, we investigated aging of the cingulum according to the location of the cingulum in each part of the cingulum after dividing the cingulum into five parts in normal subjects, using DTT parameters (fractional anisotropy (FA) and fiber number (FN)). Ninety healthy subjects (males: 44, females: 46, mean age: 49.0 years; range: 20-78 years) were enrolled in this study. Subjects were categorized according to six groups by age intervals of 10 years; each age group consisted of 15 subjects. The cingulum was divided into five parts (anterior, anterior superior, posterior superior cingulum, posterior, and inferior cingulum). The FA and FN of each part were measured. The FA value indicates the degree of directionality and integrity of white matter microstructures such as axons, myelin, and microtubules, and the FN reflects the total number of fibers in a neural tract. Age-related decline in the FA value may indicate demyelination, and a decline in the number of myelinated fibers of a neural tract can also lead to a decline of the FN. Significant differences in the FA value of the anterior cingulum and anterior superior cingulum, and the FN of the inferior cingulum were observed between age groups (AVOVA, p<0.05). A significant decrease was observed in the FA values of the anterior and anterior superior cingulum of the 60s and 70s age groups compared with those of the 20s and 30s age groups, and in the FN of the inferior cingulum of the 60s and 70s age groups compared with that of the 20s age group (LSD post hoc test, p<0.05). Aging of the cingulum began at both ends of the cingulum in the 20s or 30s, and progressed steadily at a near continuous rate over the lifespan and a significant degenerative aging effect at both ends of the cingulum occurred into the 60s, compared with the 20s or 30s.