TABLE 4.

Classification performance of early disease screening

		HC vs. prodromal PD				sMCI vs. pMCI
Brain metrics		Single brain age gap	Regional brain age gaps	Brain volumes	Brain age vector	Single brain age gap	Regional brain age gaps	Brain volumes	Brain age vector
Logistic regression (5‐fold cross‐validation)	ACC	0.5654	0.5693	0.6315	0.6164	0.5879	0.6274	0.7374	0.7579
	SEN	0.5308	0.5231	0.6231	0.6077	0.4444	0.5711	0.7089	0.7533
	SPE	0.6006	0.6160	0.6409	0.6262	0.7291	0.6855	0.7618	0.7636
	AUC	0.6104	0.6326	0.6666	0.6902	0.6397	0.6974	0.8081	0.8339
XGBoost (5‐fold cross‐validation)	ACC	0.5968	0.6005	0.6240	0.6740	0.6463	0.6574	0.7474	0.7579
	SEN	0.6000	0.6231	0.6462	0.6769	0.6200	0.6333	0.7089	0.7689
	SPE	0.5948	0.5778	0.6000	0.6711	0.6673	0.6891	0.7855	0.7491
	AUC	0.6644	0.6479	0.6629	0.7228	0.6937	0.7127	0.8002	0.8156
Logistic regression (test)	ACC	0.5862	0.5632	0.6437	0.6667	0.5588	0.6176	0.7353	0.7941
	SEN	0.5909	0.6364	0.7500	0.7727	0.5000	0.5625	0.7500	0.8125
	SPE	0.5814	0.4884	0.5349	0.5581	0.6111	0.6667	0.7222	0.7778
	AUC	0.5920	0.5745	0.6538	0.6707	0.5764	0.6528	0.8160	0.8229
XGBoost (test)	ACC	0.5862	0.5517	0.5977	0.6552	0.6471	0.5294	0.6471	0.7647
	SEN	0.7273	0.5682	0.5455	0.7500	0.6250	0.4375	0.7500	0.8750
	SPE	0.4419	0.5349	0.6512	0.5581	0.6667	0.6111	0.5556	0.6667
	AUC	0.5515	0.5740	0.6490	0.6802	0.6997	0.6007	0.8021	0.8333

Note: The best results for each classification task are shown in bold. Abbreviations: ACC, accuracy; SEN, sensitivity; SPE, specificity; AUC, area under the curve (AUC) of receiver operating characteristic.