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Table 4 Baseline characteristics of the participants according to trajectories of global cognitive function in middle-aged and older adults from CHARLS

From: Associations between social and intellectual activities with cognitive trajectories in Chinese middle-aged and older adults: a nationally representative cohort study

Characteristic Trajectory of global cognitive function p value
Class 1, persistently low (n = 1550) Class 2, persistently moderate (n = 3194) Class 3, persistently high (n = 3460)
Age (years), mean ± SD 60.45 ± 6.31 60.26 ± 6.41 59.77 ± 6.35 < 0.001
Male sex, n (%) 483 (31.2) 1677 (52.5) 2129 (61.5) < 0.001
Educational level, n (%)     < 0.001
 No formal education 1305 (84.2) 1590 (49.8) 656 (19.0)  
 Primary school 175 (11.3) 910 (28.5) 926 (26.8)  
 Middle or high school 68 (4.4) 660 (20.7) 1542 (44.6)  
 College or above 2 (0.1) 34 (1.1) 336 (9.7)  
Married, n (%) 1316 (84.9) 2826 (88.5) 3168 (91.6) < 0.001
Rural residence, n (%) 1175 (75.8) 2106 (65.9) 1625 (47.0) < 0.001
High household income, n (%) 295 (19.0) 740 (23.2) 1316 (38.0) < 0.001
Current smoker, n (%) 383 (24.7) 1134 (35.5) 1240 (35.8) < 0.001
Current drinker, n (%) 389 (25.1) 1096 (34.3) 1371 (39.6) < 0.001
Poor self-report of health, n (%) 552 (35.6) 906 (28.4) 649 (18.8) < 0.001
Depressive symptoms, n (%) 775 (50.0) 1239 (38.8) 840 (24.3) < 0.001
Restriction on ADL, n (%) 330 (21.3) 502 (15.7) 325 (9.4) < 0.001
Visual impairment, n (%) 135 (8.7) 203 (6.4) 126 (3.6) < 0.001
Hearing impairment, n (%) 159 (10.3) 254 (8.0) 187 (5.4) < 0.001
Comorbidity, n (%)*     0.715
 0 212 (13.7) 441 (13.8) 513 (14.8)  
 1 362 (23.4) 765 (24.0) 814 (23.5)  
 ≥ 2 976 (63.0) 1988 (62.2) 2133 (61.6)  
BMI (kg/m2), mean ± SD 23.01 ± 3.71 23.41 ± 4.07 23.92 ± 3.85 < 0.001
Social activity scores, n (%)     < 0.001
 0 991 (63.9) 2034 (63.7) 1894 (54.7)  
 1–2 256 (16.5) 551 (17.3) 653 (18.9)  
 ≥ 3 303 (19.5) 609 (19.1) 913 (26.4)  
Intellectual activity scores, n (%)     < 0.001
 0 1377 (88.8) 2605 (81.6) 2425 (70.1)  
 1–2 123 (7.9) 438 (13.7) 632 (18.3)  
 ≥ 3 50 (3.2) 151 (4.7) 403 (11.6)  
Global cognitive scores, mean ± SD 7.50 ± 1.92 10.74 ± 2.36 14.49 ± 2.13 < 0.001
Mental intactness scores, mean ± SD 4.63 ± 1.85 7.28 ± 2.10 9.73 ± 1.57 < 0.001
Episodic memory scores, mean ± SD 2.86 ± 1.31 3.45 ± 1.39 4.76 ± 1.47 < 0.001
  1. Abbreviations as in Table 1