Predictors of Changes in Cognitive Function in Older Korean Adults: The 2006–2018 Korean Longitudinal Study of Aging
Abstract
:1. Introduction
2. Materials and Methods
2.1. Data Source and Study Participants
2.2. Study Variables
2.2.1. Cognitive Function
2.2.2. Covariates
2.3. Statistics
3. Results
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Variables | Total (n = 727) | Normal Cognition (n = 401) | Mild Cognitive Impairment (n = 143) | Moderate/Severe Cognitive Impairment (n = 183) | p Value | |
---|---|---|---|---|---|---|
Demographics and socioeconomic status | ||||||
Age (year) | 69.3 ± 3.7 | 68.7 ± 3.4 | 69.5 ± 3.7 | 70.4 ± 4.0 | <0.001 | |
Body mass index (kg/m2) | 23.5 ± 3.2 | 23.6 ± 2.7 | 23.0 ± 3.6 | 23.6 ± 3.7 | 0.127 | |
Gender, n (%) | 330 (45.4) | 163 (40.6) | 62 (43.4) | 105 (57.4) | <0.001 | <0.001 |
397 (54.6) | 238 (59.4) | 81 (56.6) | 78 (42.6) | 78 (42.6) | ||
Existence of spouse, n (%) | 574 (79.0) | 331 (82.5) | 110 (76.9) | 133 (72.7) | 0.006 | 0.006 |
153 (21.0) | 70 (17.5) | 33 (23.1) | 50 (27.3) | 50 (27.3) | ||
Having a religion, n (%) | 435 (59.8) | 235 (58.6) | 90 (62.9) | 110 (60.1) | 0.732 | 0.732 |
292 (40.2) | 166 (48.4) | 53 (37.1) | 73 (39.3) | 73 (39.3) | ||
Residence area, n (%) | 501 (68.9) | 295 (73.6) | 86 (60.1) | 120 (65.6) | 0.048 | 0.048 |
226 (31.1) | 106 (26.4) | 57 (39.9) | 63 (34.4) | 63 (34.4) | ||
Education, n (%) | 420 (57.8) | 197 (49.1) | 86 (60.1) | 137 (74.9) | <0.001 | <0.001 |
249 (34.3) | 161 (40.1) | 49 (34.3) | 39 (21.3) | 39 (21.3) | ||
58 (8.0) | 43 (10.7) | 8 (5.6) | 7 (3.8) | 7 (3.8) | ||
Income (10,000 won) | 107 ± 196 | 123 ± 245 | 100 ± 120 | 78 ± 96 | 0.030 | |
Health behaviors | ||||||
Current/past smoking, n (%) | 232 (31.9) | 133 (33.2) | 48 (33.6) | 51 (27.9) | 0.201 | |
Heavy drinking, n (%) | 79 (10.9) | 48 (12.0) | 19 (13.3) | 12 (6.6) | 0.046 | |
Physical inactivity, n (%) | 423 (58.2) | 220 (54.9) | 80 (55.9) | 123 (67.2) | 0.005 | |
Handgrip strength (kg) | 26.7 ± 7.5 | 27.6 ± 7.5 | 26.9 ± 7.2 | 24.5 ± 7.2 | <0.001 | |
Functional limitations | ||||||
K-ADL score | 7.04 ± 0.57 | 7.01 ± 0.21 | 7.01 ± 0.08 | 7.13 ± 1.10 | 0.065 | |
IADL score | 10.23 ± 1.08 | 10.17 ± 0.61 | 10.15 ± 0.62 | 10.43 ± 1.87 | 0.015 | |
Health conditions | ||||||
CES-D score | 4.88 ± 4.31 | 4.25 ± 3.94 | 5.32 ± 4.19 | 5.91 ± 4.93 | <0.001 | |
Experience of falls, n (%) | 32 (4.4) | 17 (4.2) | 4 (2.8) | 11 (6.0) | 0.353 | |
Number of physician-diagnosed comorbidities | 0.85 ± 0.90 | 0.76 ± 0.84 | 0.89 ± 0.94 | 1.02 ± 0.98 | 0.004 | |
Number of medications | 0.68 ± 0.81 | 0.60 ± 0.77 | 0.75 ± 0.86 | 0.80 ± 0.85 | 0.011 | |
Unintentional weight loss, n (%) | 69 (9.5) | 25 (6.2) | 17 (11.9) | 27 (14.8) | 0.001 |
Cov1 | Cov2 | Cov3 | Cov4 | Cov5 | Cov6 | Cov7 | Cov8 | Cov9 | Cov10 | Cov11 | Cov12 | Cov13 | Cvo14 | Cov15 | Cov16 | Cov17 | Cov18 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
R (p value) | −0.193 (<0.001) | −0.136 (<0.001) | 0.006 (0.586) | −0.085 (<0.001) | −0.013 (0.212) | −0.107 (<0.001) | 0.234 (<0.001) | 0.152 (<0.001) | −0.071 (<0.001) | 0.063 (<0.001) | 0.069 (<0.001) | 0.185 (<0.001) | −0.017 (0.114) | −0.0114 (<0.001) | −0.029 (0.006) | −0.091 (<0.001) | −0.046 (0.001) | 0.033 (0.002) |
R2 | 0.037 | 0.018 | 0.001 | 0.007 | 0.001 | 0.011 | 0.054 | 0.023 | 0.005 | 0.004 | 0.004 | 0.034 | 0.001 | 0.013 | 0.001 | 0.008 | 0.002 | 0.001 |
VIFs | 1.173 | 2.783 | 1.088 | 1.162 | 1.118 | 1.108 | 1.295 | 1.061 | 1.644 | 1.126 | 1.143 | 2.895 | 1.738 | 1.100 | 1.031 | 2.218 | 2.073 | 1.042 |
Unadjusted Model | Adjusted Model ^ | |||||||
---|---|---|---|---|---|---|---|---|
Parameter | Categories | Estimation | 95% CI | p | Estimation | 95% CI | p | |
Intercept | 28.044 | 24.156~31.933 | <0.001 | |||||
Category of cognitive function (ref: normal cognition) | Moderate/severe cognitive impairment | −4.524 | −4.784~−4.264 | <0.001 | 0.686 | 0.303~1.069 | <0.001 | |
Mild cognitive impairment | −2.405 | −2.675~−2.135 | <0.001 | −0.081 | −0.477~0.317 | 0.691 | ||
Time (per year) | −0.494 | −0.545~−0.444 | <0.001 | 0.084 | 0.009~0.160 | 0.028 | ||
Age (per year) | −0.045 | −0.074~−0.016 | 0.003 | −0.026 | −0.067~0.015 | 0.220 | ||
Body mass index (per kg/m2) | 0.008 | −0.025~0.041 | 0.636 | 0.010 | −0.037~0.057 | 0.689 | ||
Presence of spouse (ref: no) | Yes | 0.090 | −0.187~0.367 | 0.523 | −0.096 | −0.448~0.297 | 0.632 | |
Religion (ref: no) | Yes | 0.130 | −0.091~0.351 | 0.250 | 0.185 | −0.129~0.498 | 0.247 | |
Residence (ref. village) | Town or better | 0.398 | 0.157~0.638 | 0.001 | 0.298 | −0.043~0.638 | 0.087 | |
Education (ref. college) | Elementary or less | −1.159 | −1.576~−0.742 | <0.001 | −1.126 | −1.717~−0.535 | <0.001 | |
Middle/high school | −0.642 | −1.042~−0.242 | 0.026 | −0.605 | −1.172~−0.037 | 0.037 | ||
Income (per won) | 0.001 | 0.001~0.001 | 0.017 | 0.001 | 0.000~0.002 | 0.016 | ||
Current/past smokers (ref. yes) | No | −0.238 | −0.508~0.032 | 0.084 | −0.010 | −0.393~0.372 | 0.957 | |
Heavy drinking (ref. yes) | No | −0.431 | −0.776~−0.086 | 0.014 | −0.389 | −0.878~0.100 | 0.118 | |
UWL (ref. yes) | No | −0.592 | −0.942~−0.242 | 0.001 | −0.735 | −1.231~−0.239 | 0.004 | |
Fall experience (ref. yes) | No | −0.682 | −1.186~−0.178 | 0.008 | −0.458 | −1.172~0.256 | 0.208 | |
Number of diagnosed diseases (ref: 0) | 0.065 | −0.170~0.301 | 0.586 | 0.017 | −0.317~0.350 | 0.992 | ||
Number of medications (ref: 0) | −0.143 | −0.414~0.119 | 0.285 | −0.163 | −0.534~0.208 | 0.388 | ||
Physical activity (ref. inactive) | Active | 0.080 | −0.146~0.306 | 0.489 | 0.202 | −0.118~0.253 | 0.216 | |
Handgrip strength (per kg) | 0.034 | 0.011~0.056 | 0.004 | 0.039 | 0.007~0.072 | 0.018 | ||
CES_D score | −0.008 | −0.033~0.017 | 0.552 | −0.018 | −0.054 ~0.017 | 0.319 | ||
KADL score | −0.183 | −0.359~−0.007 | 0.042 | −0.026 | −0.274~−0.274 | 0.211 | ||
Category of cognitive function × time (ref. normal cognition) | Moderate/severe cognitive impairment × time | −1.740 | −1.877~−1.604 | <0.001 | ||||
Mild cognitive impairment × time | −0.775 | −0.922~−0.628 | <0.001 | |||||
Random variance | ||||||||
Intercept | 0.472 | 0.184~1.209 | 0.037 | 0.037 | ||||
Linear slope | 0.380 | 0.195~0.566 | <0.001 | <0.001 | ||||
Residual | 7.675 | 7.354~8.011 | <0.001 | <0.001 |
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Kang, M.; Lee, I.; Hong, H.; Kim, J.; Kang, H. Predictors of Changes in Cognitive Function in Older Korean Adults: The 2006–2018 Korean Longitudinal Study of Aging. Int. J. Environ. Res. Public Health 2021, 18, 6345. https://doi.org/10.3390/ijerph18126345
Kang M, Lee I, Hong H, Kim J, Kang H. Predictors of Changes in Cognitive Function in Older Korean Adults: The 2006–2018 Korean Longitudinal Study of Aging. International Journal of Environmental Research and Public Health. 2021; 18(12):6345. https://doi.org/10.3390/ijerph18126345
Chicago/Turabian StyleKang, Minjeong, Inhwan Lee, Haeryun Hong, Jeonghyeon Kim, and Hyunsik Kang. 2021. "Predictors of Changes in Cognitive Function in Older Korean Adults: The 2006–2018 Korean Longitudinal Study of Aging" International Journal of Environmental Research and Public Health 18, no. 12: 6345. https://doi.org/10.3390/ijerph18126345