Table 2.

The correlations between plasma biomarkers and clinical parameters in the PD group

	GFAP		NfL		p-tau181		Aβ42/40		Aβ40		Aβ42
	rs	p value	rs	p value	rs	p value	rs	p value	rs	p value	rs	p value
Age at examination	0.5479	< 0.0001	0.5552	< 0.0001	0.4505	< 0.0001	− 0.2206	0.0664	0.4042	0.0005	0.2123	0.0777
Sex		0.1525		0.2287		0.6082		0.5834		0.5197		0.8394
Age at onset	0.4023	0.0006	0.3816	0.0012	0.3802	0.0012	− 0.1853	0.1246	0.2738	0.0218	0.1066	0.3799
Disease duration	0.0444	0.7149	0.1310	0.2833	− 0.0042	0.9722	0.0127	0.9166	0.1100	0.3646	0.1400	0.2476
Education	− 0.1837	0.1278	− 0.2194	0.0701	0.0632	0.6035	0.1069	0.3783	− 0.1409	0.2448	− 0.0951	0.4337
LEDD	0.0896	0.4605	0.2201	0.0691	0.0923	0.4474	− 0.1220	0.3145	0.1051	0.3867	0.2202	0.0670
MDS-UPDRS I	0.2676	0.0262	0.1595	0.1938	0.1832	0.1319	− 0.0633	0.6055	0.1214	0.3206	− 0.0158	0.8975
MDS-UPDRS II	0.0134	0.9131	0.3071	0.0109	0.0704	0.5654	− 0.0029	0.9812	0.1393	0.2538	0.0463	0.7056
MDS-UPDRS III	0.0325	0.7940	0.1627	0.1919	0.1695	0.1703	− 0.0885	0.4763	0.0920	0.4589	− 0.0149	0.9048
MDS-UPDRS IV	0.0308	0.8063	0.1395	0.2676	− 0.1217	0.3303	− 0.0942	0.4519	0.2027	0.1027	0.1187	0.3425
HY	0.3305	0.0052	0.4941	< 0.0001	0.4245	0.0002	− 0.1864	0.1222	0.2572	0.0316	0.0860	0.4792
PDQ-39 SI	0.0765	0.5292	0.1150	0.3467	0.1341	0.2682	− 0.0210	0.8627	0.0968	0.4251	0.0169	0.8893
SCOPA-AUTO	0.0179	0.8832	− 0.0639	0.6018	− 0.0928	0.4450	0.0857	0.4803	− 0.0542	0.6556	0.0182	0.8811
GDS-15	0.1813	0.1331	0.1631	0.1807	− 0.0063	0.9587	0.0447	0.7135	0.0337	0.7818	0.0779	0.5217
J-QUIP	0.1016	0.4027	0.0442	0.7185	0.1395	0.2493	0.2160	0.0725	0.0633	0.6025	0.1888	0.1175
RBDSQ-J	0.0883	0.4671	0.1551	0.2033	0.1679	0.1646	− 0.1512	0.2116	0.1656	0.1706	0.0717	0.5552
ESS	− 0.0363	0.7657	0.0290	0.8129	0.0530	0.6628	0.0369	0.7619	0.1339	0.2693	0.1236	0.3081
OSIT-J score	− 0.2725	0.0235	− 0.2064	0.0913	− 0.2340	0.0530	0.0439	0.7205	− 0.0367	0.7648	− 0.0919	0.4524
MMSE	− 0.5269	< 0.0001	− 0.3027	0.0115	− 0.1655	0.1711	0.2837	0.0173	− 0.2494	0.0373	− 0.1205	0.3202
ACE-R total score	− 0.4616	< 0.0001	− 0.4456	0.0001	− 0.2507	0.0363	0.1500	0.2151	− 0.3039	0.0105	− 0.1910	0.1132
MoCA-J total score	− 0.4993	< 0.0001	− 0.3865	0.0011	− 0.2243	0.0640	0.1792	0.1406	− 0.1699	0.1627	− 0.0597	0.6261
FAB	− 0.4081	0.0006	− 0.3694	0.0021	− 0.2702	0.0259	0.1194	0.3320	− 0.1194	0.3320	− 0.0581	0.6382

Spearman’s rank correlation test was used to determine significant correlations

GFAP glial fibrillary acidic protein, NfL neurofilament light chain, p-tau phosphorylated tau, Aβ amyloid beta, PD Parkinson's disease, LEDD Levodopa equivalent daily dose, MDS-UPDRS Movement Disorder Society’s Unified Parkinson's disease Rating Scale, HY Hoehn − Yahr scale, PDQ-39 SI Parkinson's Disease Questionnaire-39 Summary Index, SCOPA-AUT Scales for Outcomes in Parkinson's Disease-Autonomic, GDS-15 Geriatric Depression Scale-15, J-QUIP Japanese version of the Questionnaire for Impulsive − Compulsive Disorders in Parkinson's Disease, RBDSQ-J Japanese version of the REM Sleep Behavior Disorder Screening Questionnaire, ESS Epworth Sleepiness Scale, OSIT-J Odor Stick Identification Test for Japanese, MMSE Mini-Mental State Examination, ACE-R Addenbrooke’s Cognitive Examination-Revised, MoCA-J Japanese version of the Montreal Cognitive Assessment, FAB Frontal Assessment Battery

*Bold letters indicate a correlation with a statistically significant difference

**Underlines indicate a moderate or higher correlation coefficient (absolute value of rs > 0.4)