Table 1 – Aβ(−) trained brain ages show significant differences between AD diagnostic groups and amyloid status in CN participants:

Results of the multivariable linear regression analysis of the Aβ(−) trained model are shown for cognitive diagnostic groups and amyloid status as a sub-analysis of the CN group. The reference test group was CN for comparison between diagnostic groups and CN-Aβ(−) PITT for CN subgroups. (CA = chronological age)

Term	Estimate	Std Error	t Ratio	p-value	Lower 95%	Upper 95%
Cognitive diagnostic groups (CN as reference)
Intercept	35.291579	2.243782	15.73	<.0001	30.882867	39.70029
CA	0.5093958	0.029011	17.56	<.0001	0.4523937	0.5663979
EMCI	1.020452	0.467582	2.18	0.0296	0.1017208	1.9391832
LMCI	4.2385508	0.551762	7.68	<.0001	3.1544176	5.322684
AD	6.7979684	0.572472	11.87	<.0001	5.6731422	7.9227945
Amyloid status in CN group (CN-Aβ(−) PITT as reference)
Intercept	34.463869	4.644971	7.42	<.0001	25.274351	43.653388
CA	0.5050906	0.060237	8.39	<.0001	0.3859185	0.6242627
CN-Aβ(−)	1.0575062	0.781668	1.35	0.1784	−0.48893	2.6039429
CN-Aβ(+)	1.9821045	0.781679	2.54	0.0124	0.4356468	3.5285621