请用中文对下列段落的主要内容进行翻译：A subgroup analysis was performed to test differences in predictive performance between participants who were cognitively unimpaired (CU) and those with cognitive impairment (CI) consisting of MCI or dementia (Supplemental Table 1, online resource). CI participants were more likely to be APOE ε4 carriers (p = 0.028, Pearson Chi-squared test) and have worse Mayo-PACC cognitive scores (p < 0.001, Kruskal–Wallis rank-sum test) but no other differences in demographics. CI participants has significantly higher neuropathology scores across all four metrics (p < 0.01, Pearson Chi-squared test). With respect to plasma biomarkers, CI participants had significantly higher levels of GFAP (p < 0.001, Kruskal–Wallis rank-sum test) but not NfL, p-tau181, or Aβ42/40 ratio.

In univariate analyses (Supplemental Table 5, online resource), separation by cognitive status resulted in a general improvement in prediction performance in p-tau181 across all neuropathology metrics with CV AUC for ADNC, Braak staging, Neuritic plaque, and Thal phase of 0.755 (p = 0.009), 0.745 (p = 0.213), 0.725 (p = 0.006), and 0.848 (p < 0.001) amongst those with MCI or dementia versus 0.625, 0.663, 0.637, 0.651, respectively, for those CU. There was no significant difference between subgroups among Aβ42/40 ratio, GFAP, or NfL, although there was a trend towards improvement of prediction of ADNC with GFAP, Neuritic plauqe with GFAP and Aβ42/40 ratio, and Thal phase with GFAP and Aβ42/40 ratio. Demographic variables and cognitive scores performed similarly in both subgroups (Table 4).

In the multivariate analyses, there was a general improved predictive performance in the MCI/dementia subgroup across all four neuropathology scales when plasma biomarkers were included in the available variable pool (Table 4). In the case of ADNC, the best prediction performance was seen with the complete variable pool in participants with MCI/dementia vs cognitively unimpaired (CV AUC 0.851 vs 0.659, p = 0.005), whereas cognitively unimpaired individuals showed best performance in the demographics plus Mayo-PACC pool (CV AUC of 0.700 vs 0.513 in the MCI/dementia subgroup, p < 0.001). Variables chosen by the MCI/dementia subgroup included GFAP, NfL, and p-tau181 whereas the best prediction of ADNC in cognitively unimpaired individuals included variables of APOE ε4 carrier status and age at visit but did not include plasma biomarkers. Groupwise comparisons between variable pools showed a statistical improvement in prediction of ADNC when plasma biomarkers were included in the MCI/dementia subgroup (p < 0.001) but not in the cognitively unimpaired group. Braak stage prediction was best in the variable pool of plasma plus demographics CV AUC 0.733 [0.634, 831] in the MCI/dementia subgroup with GFAP and p-tau181 as variables selected and the plasma biomarkers pool for the cognitively unimpaired group CV AUC 0.741 [0.626, 0.856] using GFAP alone. Despite a trend towards improvement, there was no statistically significant difference between subgroups or across variable pools.

The best neuritic plaque score prediction was achieved in the MCI/dementia subgroup which was predicted using the plasma biomarkers plus demographics (CV AUC 0.797 vs 0.630, p = 0.003) using all plasma biomarkers in the MCI/dementia subgroup versus GFAP and APOE ε4 carrier status in the cognitively unimpaired subgroup. Without plasma biomarkers, prediction was significantly better in the cognitively unimpaired group (CV AUC 0.602 vs 0.494, p = 0.006). There were no groupwise differences between variable pools in the cognitively unimpaired subgroup, but there was an improvement in prediction when including plasma biomarkers in the MCI/dementia subgroup (p < 0.001).

The best prediction of Thal amyloid phase was observed in the MCI/dementia subgroup using the complete variable pool with a CV AUC of 0.796 using GFAP, p-tau181, and APOE ε4 carrier status vs a CV AUC of 0.648 in the cognitively unimpaired, using APOE ε4 carrier status and age at visit (p < 0.022). The best performance in the cognitively unimpaired was in the demographics and cognitive scores variable pool using APOE ε4 carrier status and age at visit, with similar performance in the MCI/dementia subgroup using APOE ε4 carrier status alone (CV AUC 0.686 vs 0.698, p = 0.858). Groupwise comparisons showed no difference in performance between variable pools in either subgroup.