Serum 1, 25-Hydroxyvitamin D: A Useful Index of Cognitive and Physical Functional Impairment in Healthy Older Adults in Japan: A Pilot Study

We enrolled 23 Japanese men (age: 76.0 ± 8.7) and 17 women (age: 78.3 ± 9.3) in this study. The physical function of even a person getting on a wheelchair could be tested in all subjects. Blood was collected by venipuncture and the serum 1, 25-hydroxy vitamin D (1, 25OHD) concentration was measured. The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment-Japanese version (MoCA-J) was used for the cognitive function test. Physical function was measured objectively using the Timed UP and Go (TUG) and 4-m walking test (4MWS). A significant positive correlation was found between serum 1, 25OHD and MMSE or MoCA-J. It is expected that an elderly person can maintain a mean serum 1, 25OHD level of about 100 pg/mL for preventing early cognitive disorder. In the present study, a significant positive correlation was found between urinary 25-hydroxy vitamin D (25OHD)/creatinine and MMSE or MoCA-J. Our results showed that urinary 25OHD might be a useful biomarker for predicting cognitive disorder. There was a significant negative correlation between serum 1, 25OHD and TUG or 4MWS. These findings suggest that serum 1, 25OHD levels might serve as a useful index to improve cognitive and physical functional impairment.