Early Diagnosis of Dementia Based on D-amino Acids

Amino acids, like DNA and lipids, are components that play an important role in our life activities. Amino acids include proline (Pro) and serine (Ser), and each of these amino acids has L- and D-configurations. These isomers are enantiomers and have the same shape and size.
For many years, it was believed that only L-amino acids existed in mammals, including humans. However, the presence of trace amounts of D-amino acids has been discovered with the development of analytical technology. Furthermore, D-amino acids have been associated with aging and various diseases, and have attracted considerable attention around the world.

Kao has developed a chiral tandem liquid chromatography–tandem mass spectrometry system that enables simultaneous analysis of DL-amino acids in a short time with high sensitivity. We clarified the usefulness of blood D-amino acid levels to assess cognitive function based on the system in collaboration with the Tokyo Metropolitan Institute for Geriatrics and Gerontology.
We simultaneously analyzed blood DL-amino acids from 305 subjects who were classified into control, mild cognitive impairment (MCI), and dementia to investigate the relationship between DL-amino acid levels and cognitive function. The results showed that the enantiomeric proportion (D/(D + L) × 100) in the MCI group was significantly higher than that in the control group, which could be a new blood biomarker for early diagnosis of cognitive decline^*1 .

Kao will advance D-amino acid research and apply it to the life care field.