Table 4.

Associations between cognitive test scores and PD diagnosis in participants without cognitive impairment

Cognitive test	Semi-partial correlations	B a	95% CI	p value
HVLT-R immediate (total words recalled)
Diagnosis
HV		Reference
PD	−0.067	−0.49	−1.34, 0.36	.258
Age, years	−0.055	−0.03	−0.09, 0.04	.396
Education, years	0.075	0.12	−0.08, 0.31	.239
Sex
Female		Reference
Male	0.121	0.86	0.01, 1.73	.048
APOE ε4		0.57	−0.28, 1.41	.191
MoCA score	0.148	0.26	0.07, 0.45	.007
GDS-15 score	−0.079	−0.21	−0.46, 0.05	.109
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	−0.122	−1.20	−2.38, -0.02	.046
Stanford University	−0.155	−1.50	−2.71, -0.30	.015
Johns Hopkins University	−0.005	−0.07	−1.72, 1.59	.938
HVLT-R delayed (total words recalled)
Diagnosis
HV		Reference
PD	−0.135	−0.43	−0.80, -0.05	.025
Age, years	−0.909	−0.02	−0.05, 0.00	.103
Education, years	0.101	0.07	−0.01, 0.15	.087
Sex
Female		Reference
Male	0.205	0.65	0.27, 1.03	.001
APOE ε4 allele	0.023	0.08	−0.30, 0.46	.682
MoCA score	0.128	0.10	0.01, 0.19	.032
GDS-15 score	−0.075	−0.09	−0.22, 0.05	.218
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	−0.163	−0.71	−1.23, -0.20	.007
Stanford University	−0.062	−0.27	−0.79, 0.26	.323
Johns Hopkins University	−0.012	−0.08	−0.81, 0.66	.841
Trail Making Test, Part B (seconds) b, c
Diagnosis
HV		Reference
PD	0.099	4.84	0.05, 9.63	.048
Trail Making, Part A	0.342	0.83	0.58, 1.09	<.001
Age, years	0.211	0.75	0.35, 1.15	<.001
Education, years	−0.194	−2.03	−3.17, -0.89	<.001
Sex
Female		Reference
Male	0.007	0.32	−4.46, 5.10	.896
APOE ε4 allele	−0.037	−1.94	−7.50, 3.63	.496
MoCA score	−0.018	−0.21	−1.46, 1.05	.748
GDS-15 score	0.015	0.26	−1.47, 1.99	.770
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	−0.111	−7.33	−12.38, -2.29	.004
Stanford University	0.046	2.97	−3.53, 9.47	.371
Johns Hopkins University	0.016	1.63	−7.63, 10.89	.730
Letter-Number Sequencing (total score)
Diagnosis
HV		Reference
PD	−0.010	−0.05	−0.54, 0.45	.858
Age, years	−0.216	−0.07	−0.11, -0.03	.001
Education, years	0.171	0.16	0.06, 0.27	.003
Sex
Female		Reference
Male	−0.041	−0.18	−0.72, 0.36	.512
APOE ε4	0.006	0.03	−0.63, 0.69	.929
MoCA score	0.122	0.13	0.02, 0.24	.025
GDS-15 score	−0.070	−0.11	−0.27, 0.05	.173
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	0.067	0.40	−0.38, 1.19	.316
Stanford University	−0.032	−0.20	−0.87, 0.48	.571
Johns Hopkins University	−0.035	−0.31	−1.20, 0.58	.496
Digit Symbol (total score) b, c
Diagnosis
HV		Reference
PD	−0.203	−3.77	−5.76, 1.77	<.001
Trail Making, Part A	−0.270	−0.25	−0.39, -0.11	<.001
Age, years	−0.172	−0.23	−0.37, -0.10	<.001
Education, years	0.096	0.39	−0.00, 0.77	.052
Sex
Female		Reference
Male	0.159	2.90	0.97, 4.83	.003
APOE ε4 allele	−0.0002	−0.00	−1.93, 1.92	.997
MoCA score	0.046	0.17	−0.33, 0.68	.499
GDS-15 score	0.019	0.12	−0.48, 0.73	.693
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	0.184	4.64	1.73, 7.54	.002
Stanford University	0.061	1.51	−1.22, 4.25	.278
Johns Hopkins University	0.009	0.34	−3.34, 4.02	.857
Semantic verbal fluency (total correct words)
Diagnosis
HV		Reference
PD	−0.214	−2.02	−3.12, -0.92	<.001
Age, years	−0.268	−0.18	−0.26, -0.10	<.001
Education, years	0.137	0.28	0.04, 0.51	.022
Sex
Female		Reference
Male	0.031	0.29	−0.78, 1.36	.597
APOE ε4	−0.047	−0.48	−1.61, 0.64	.401
MoCA score	0.078	0.18	−0.06, 0.42	.146
GDS-15 score	0.096	0.33	−0.05, 0.70	.089
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	0.046	0.59	−0.88, 2.06	.433
Stanford University	0.013	0.17	−1.22, 1.56	.814
Johns Hopkins University	−0.013	−0.24	−2.30, 1.82	.819
Phonemic verbal fluency (total correct words)
Diagnosis
HV		Reference
PD	−0.107	−2.57	−5.26, 0.12	.061
Age, years	−0.028	−0.05	−0.24, 0.14	.618
Education, years	0.316	1.63	1.06, 2.20	<.001
Sex
Female		Reference
Male	0.054	1.30	−1.39, 3.98	.345
APOE ε4	0.038	0.99	−2.47, 4.44	.575
MoCA score	0.225	1.31	0.77, 1.86	<.001
GDS-15 score	0.140	1.21	0.31, 2.12	.009
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	0.096	3.16	−0.81, 7.14	.119
Stanford University	−0.071	−2.30	−5.81, 1.22	.201
Johns Hopkins University	−0.002	−0.12	−5.40, 5.17	.966
Judgment of Line Orientation (total score)
Diagnosis
HV		Reference
PD	−0.081	−0.32	−0.77, 0.14	.171
Age, years	−0.076	−0.02	−0.06, 0.01	.213
Education, years	0.084	0.07	−0.02, 0.16	.115
Sex
Female		Reference
Male	−0.331	−1.29	−1.73, -0.84	<.001
APOE ε4	−0.036	−0.15	−0.65, 0.34	.545
MoCA score	0.040	0.04	−0.08, 0.16	.546
GDS-15 score	−0.008	−0.01	−0.17, 0.15	.887
Site
VA Puget Sound Health Care System/ University of Washington		Reference
VA Portland Health Care System/ Oregon Health & Sciences University	0.019	0.10	−0.43, 0.63	.707
Stanford University	−0.082	−0.43	−1.08, 0.21	.189
Johns Hopkins University	−0.042	−0.33	−1.18, 0.52	.443

^aUnstandardized beta coefficients derived from linear regression analyses including diagnosis, age, sex, education, APOE ε4 allele, GDS-15 total score, MoCA total score, and site

^bAnalyses control additionally for Trail Making, Part A scores to account for motor slowing common among PD participants

^cHigher scores represent worse performance

^dBold font indicates statistical significance (p < 0.01)

Abbreviations: APOE, apolipoprotein E, CI, confidence interval; GDS-15, 15-item Geriatric Depression Scale; HV, healthy volunteers; HVLT-R, Hopkins Verbal Learning Test-Revised; MoCA, Montreal Cognitive Assessment; PD, Parkinson’s disease; VA, Veterans Affairs