Stroke is an important risk factor for dementia. Epidemiological studies have indicated a high incidence of dementia in stroke patients. However, no effective biomarker for the diagnosis of post-stroke dementia (PSD) has been established. D-amino acid oxidase (DAO) is a flavin-dependent enzyme widely distributed in the central nervous system. DAO oxidizes D-amino acids, a process which generates neurotoxic hydrogen peroxide and leads to neurodegeneration. Since ischemic injury induces peroxisome biogenesis in neurons, DAO expression may also be regulated after stroke. Dr. Yu-Li Liu from the Center for Neuropsychiatric Research collaborated with Dr. Yi-Chun Chen at Chang Gung Memorial Hospital to examine post-stroke plasma DAO levels and determine whether they can be used as a biomarker for PSD.
Dr. Liu and team recruited 53 patients with PSD, 20 post-stroke patients without dementia (PSNoD), and 71 age- and gender-matched normal controls in the study. Cognitive function was evaluated at more than 30 days post-stroke. Plasma DAO was measured using the enzyme-linked immunosorbent assay. White matter hyperintensity (WMH), a neuroimaging biomarker of cerebral small vessel diseases, was determined by magnetic resonance imaging. The team found that plasma DAO levels were independently higher in PSD subjects than in PSNoD subjects or the controls and were correlated with the WMH load in stroke patients. Using an area under the curve (AUC)/receiver operating characteristic analysis, plasma DAO levels were significantly reliable for the diagnosis of PSD. The sensitivity and specificity of the optimal cut-off value of 321 ng/ml of plasma DAO for the diagnosis of PSD were 75 and 88.7%, respectively. These data supported that plasma DAO levels were increased in PSD patients and correlated with brain WMH, independent of age, gender, hypertension, and renal function. Plasma DAO levels may therefore aid in PSD diagnosis. These findings have been published in Frontiers in Neurology (2019 Apr;10:Article number 402).
Citation: Chen, YC; Chou, WH; Tsou, HH; Fang, CP; Liu, TH; Tsao, HH; Hsu, WC; Weng, YC; Wang, Y; Liu, YL. A post-hoc study of D-amino acid oxidase in blood as an indicator of post-stroke dementia. Frontiers in Neurology. 2019 Apr;10:Article number 402.