@article{oai:repo.qst.go.jp:00081549,
 author = {Ohmichi, Takuma and Kasai, Takashi and Shinomoto, Makiko and Matsuura, Jun and Koizumi, Takashi and Fukiko, Kitani-Morii and Tatebe, Harutsugu and Sasaki, Hidenao and Mizuno, Toshiki and Tokuda, Takahiko and Harutsugu, Tatebe and Takahiko, Tokuda},
 journal = {frontiers in Neurology},
 month = {Dec},
 note = {Caffeine is considered to be a neuroprotective agent against Parkinson’s disease (PD)
and is expected to offer a blood-based biomarker for the disease.We herein investigated
the ability of this biomarker to discriminate between PD and neurodegenerative diseases.
To quantify caffeine concentrations in serum and plasma, we developed a specific
competitive enzyme-linked immunosorbent assay (ELISA). To validate the diagnostic
performance of the assay, we conducted a case control-study of two independent
cohorts among controls and patients with PD and multiple system atrophy (MSA).
Parallelism, recovery rate, and intra- and inter-assay precision of our assay were within
the standard of acceptance. In the first cohort of 31 PD patients, 18 MSA patients and 33
age-matched controls, serum caffeine levels were significantly lower in PD patients than
in Controls (p = 0.018). A similar trend was also observed in the MSA group, but did not
reach the level of significance. In the second cohort of 50 PD patients, 50 MSA patients
and 45 age-matched controls, plasma caffeine levels were significantly decreased in
both PD and MSA groups compared to Controls (p < 0.001). This originally developed
ELISA offered sufficient sensitivity to detect caffeine in human serum and plasma. We
reproducibly confirmed decreased blood concentrations of caffeine in PD compared to
controls using this ELISA. A similar trend was observed in the MSA group, despite a lack
of consistent significant differences across cohorts.},
 title = {Quantification of Blood Caffeine Levels in Patients With Parkinson's Disease and Multiple System Atrophy by Caffeine ELISA},
 volume = {11},
 year = {2020}
}