Association between plasma α-aminobutyric acid and depressive symptoms in older community-dwelling adults in Japan

Aim To examine the association between depressive symptoms and plasma amino acid related metaboli in older adults. Methods A total of 152 older adults aged >= 65 years, residing in Niigata, Japan, were used for analysis. We evaluated depressive symptoms using the Geriatric Depression Scale-15, which has been validated in older community-dwelling individuals, and used a cut off score of >= 5 to classify participants as having depressive symptoms. We used high-performance liquid chromatography-electrospray ionization mass spectrometry to measure the concentrations of plasma amino acid-related metabolites, and carried out logistic regression analysis to assess the association between depressive symptoms and plasma amino acid-related metabolites. Results Of the 119 older adults (mean age 76.3 years) included in the analysis, 22 were classified as having depressive symptoms (depressive group). There were no significant differences in physical and cognitive impairments between participants in the depressive and non-depressive groups. The plasma alpha-aminobutyric acid (AABA) level was significantly lower in the depressive group than in the non-depressive group (P < 0.001). Logistic regression analysis showed the best-fit model, which included AABA, leucine, threonine, hydroxyl proline and histidine levels (area under the receiver operating characteristic curve 0.8346; 95% confidence interval 0.7365-0.9326). In particular, the plasma AABA level was strongly associated with depressive symptoms. Conclusions Plasma AABA level is significantly associated with depression symptoms in older community-dwelling adults in Japan. Thus, plasma AABA might serve as a potential marker of depression in older adults aged >= 65 years. Geriatr Gerontol Int 2019; 19: 254-258.