Skip to main content

Table 1 Descriptive characteristics of the study population

From: Subjective cognitive decline and subsequent dementia: a nationwide cohort study of 579,710 people aged 66 years in South Korea

  Total (n = 579,710) Non-SCD group (n = 357,654) SCD group (n = 222,056) P value
Sex     < 0.0001
 Male 266,311 (45.9%) 173,795 (48.6%) 92,516 (41.7%)  
 Female 313,399 (54.1%) 183,859 (51.4%) 129,540 (58.3%)  
Income     < 0.0001
 Medicaid aid 33,023 (5.7%) 19,101 (5.3%) 13,922 (6.3%)  
 Group 1 (1st to 6th ventiles) 125,064 (21.6%) 82,491 (23.1%) 42,573 (19.2%)  
 Group 2 (7th to 14th ventiles) 178,625 (30.8%) 110,550 (30.9%) 68,075 (30.7%)  
 Group 3 (15th to 20th ventiles) 242,998 (41.9%) 145,512 (40.7%) 97,486 (43.9%)  
Lifestyle factors
 Smoking status     < 0.0001
  Never smoked 406,103 (70.1%) 250,238 (70.0%) 155,865 (70.2%)  
  Ex-smoker 95,502 (16.5%) 57,647 (16.1%) 37,855 (17.0%)  
  Current smoker 78,105 (13.5%) 49,769 (13.9%) 28,336 (12.8%)  
 Alcohol consumption     < 0.0001
  No drinking: rarely 508,547 (87.7%) 314,324 (87.9%) 194,223 (87.5%)  
  Light drinking: 3–4 times per week 38,840 (6.7%) 23,954 (6.7%) 14,886 (6.7%)  
  Heavy drinking: almost every day 32,323 (5.6%) 19,376 (5.4%) 12,947 (5.8%)  
 Exercise frequency     < 0.0001
  Exercise 327,775 (56.5%) 200,723 (56.1%) 127,052 (57.2%)  
  No exercise 251,935 (43.5%) 156,931 (43.9%) 95,004 (42.8%)  
Healthcare visit frequency*
 First quartile 144,858 (25.0%) 93,542 (26.2%) 51,316 (23.1%)  
 Second quartile 144,945 (25.0%) 89,583 (25.1%) 55,362 (24.9%)  
 Third quartile 144,988 (25.0%) 88,208 (24.7%) 56,780 (25.6%)  
 Fourth quartile 144,919 (25.0%) 86,321 (24.1%) 58,598 (26.4%)  
Past medical history
 Psychiatric disorders
  Depression 48,653 (8.4%) 26,676 (7.5%) 21,977 (9.9%) < 0.0001
  Bipolar affective disorder 1891 (0.3%) 1059 (0.3%) 832 (0.4%) < 0.0001
  Substance use disorder 3522 (0.6%) 2035 (0.6%) 1487 (0.7%) < 0.0001
  Panic disorder 2315 (0.4%) 1298 (0.4%) 1017 (0.5%) < 0.0001
  Obsessive-compulsive disorder 671 (0.1%) 370 (0.1%) 301 (0.1%) 0.001
  Personality disorder 237 (0.0%) 142 (0.0%) 95 (0.0%) 0.619
  Other psychiatric disorders 140,212 (24.2%) 81,764 (22.9%) 58,448 (26.3%) < 0.0001
 Neurological diseases
  Cerebrovascular disease 80,212 (13.8%) 46,895 (13.1%) 33,317 (15.0%) < 0.0001
  Epilepsy 8622 (1.5%) 4807 (1.3%) 3815 (1.7%) < 0.0001
  Migraines 43,466 (7.5%) 25,304 (7.1%) 18,162 (8.2%) < 0.0001
  Headaches 70,207 (12.1%) 40,791 (11.4%) 29,416 (13.2%) < 0.0001
  Sleep disorder 63,769 (11.0%) 36,635 (10.2%) 27,134 (12.2%) < 0.0001
  Head injury 64,698 (11.2%) 39,459 (11.0%) 25,239 (11.4%) < 0.0001
 Medical diseases
  Diabetes mellitus 154,977 (26.7%) 94,346 (26.4%) 60,631 (27.3%) < 0.0001
  Myocardial infarction 8504 (1.5%) 5245 (1.5%) 3259 (1.5%) 0.981
  Congestive heart failure 31,952 (5.5%) 19,222 (5.4%) 12,730 (5.7%) < 0.0001
  Liver disease 146,020 (25.2%) 88,392 (24.7%) 57,628 (26.0%) < 0.0001
  Renal disease 5669 (1.0%) 3476 (1.0%) 2193 (1.0%) 0.564
  Peptic ulcer disease 259,797 (44.8%) 155,929 (43.6%) 103,868 (46.8%) < 0.0001
  Thyroid gland disorder 40,236 (6.9%) 23,104 (6.5%) 17,132 (7.7%) < 0.0001
  Asthma 123,850 (21.4%) 74,598 (20.9%) 49,252 (22.2%) < 0.0001
  Cancer 41,290 (7.1%) 24,845 (6.9%) 16,445 (7.4%) < 0.0001
 Medication history
  HMG-CoA reductase inhibitors 128,527 (22.2%) 77,725 (21.7%) 50,802 (22.9%) < 0.0001
  Diabetes medication 84,015 (14.5%) 51,878 (14.5%) 32,137 (14.5%) 0.735
  Antihypertensive medication 288,262 (49.7%) 178,093 (49.8%) 110,169 (49.6%) 0.180
  Antidepressants 31,079 (5.4%) 17,216 (4.8%) 13,863 (6.2%) < 0.0001
  Benzodiazepines and sleeping pills 92,444 (15.9%) 53,108 (14.8%) 39,336 (17.7%) < 0.0001
  Antiplatelet medication 140,615 (24.3%) 86,071 (24.1%) 54,544 (24.6%) < 0.0001
 Depression Screening Questionnaire score, mean (SD) 0.34 (0.79) 0.23 (0.67) 0.53 (0.92) < 0.0001
Laboratory findings
 Cholesterol level, mean (SD), mg/dL
  LDL cholesterol 117.47 (35.58) 117.26 (35.55) 117.81 (35.64) < 0.0001
  HDL cholesterol 53.63 (13.64) 53.57 (13.61) 53.73 (13.68) < 0.0001
  Triglycerides 134.31 (70.64) 134.80 (70.97) 133.54 (70.10) < 0.0001
  Fasting glucose 101.89 (20.96) 102.11 (21.10) 101.52 (20.73) < 0.0001
  Hemoglobin 13.59 (1.40) 13.63 (1.40) 13.54 (1.39) < 0.0001
 Physical examination findings
  Body mass index 24.29 (2.98) 24.31 (2.99) 24.25 (2.98) < 0.0001
  Systolic blood pressure 128.74 (15.43) 129.05 (15.44) 128.22 (15.41) < 0.0001
  Diastolic blood pressure 78.01 (9.73) 78.18 (9.73) 77.73 (9.73) < 0.0001
  1. HDL high-density lipoprotein, LDL low-density lipoprotein, SCD subjective cognitive decline, SD standard deviation
  2. *The fourth quartile group had the highest frequency of medical visits