Table 4.

PCA of traditional tests

	PCA 3
	Component
	1	2
	Memory (MEMT)	Executive function (EFT)
Logical Memory immediate recall	0.875
Logical Memory delayed recall	0.807
FNAME	0.727
MMSE-DR	0.626
FAS		0.83
ANT		0.77
MMSE-attention		0.718
Trails B		−0.648
% Explained variance	34%	33%
Total % explained variance	67%

Abbreviations: PCA, principal component analysis; FNAME, Face Name Associative Memory-cued first letter; MMSE-DR, Mini–Mental State Examination delayed recall subscore; FAS, verbal fluency under phonemic constraint to letters F-A-S; ANT, verbal fluency under categorical constraint (animals); MMSE-attention, Mini–Mental State Examination attention subscore.

NOTE. PCA was conducted using varimax with Kaiser Normalization. Factors with eigenvalues greater than 1, with a maximum iteration of 25, were extracted—factor loadings shown after orthogonal rotation.

NOTE. PCA 3 rotation converged in 3 iterations. The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy = 0.75.

NOTE. Owing to missing data for FNAME and Logical Memory tests added to the protocol at a later date, alternate factor-based scores for the traditional memory domain were calculated leveraging the most available data (i.e., average of MMSE-DR and Logical Memory when FNAME was missing). This factor-based score is noted as MEM_T1 and is considered in certain analyses by clinical group.