TABLE 2.
Sample characteristics.
| Range | ||
| No. of participants | 7,152 | |
| Duration between baseline and MRI scan (years) | 7.55 | 4.29–10.85 |
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| Demographics | ||
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| Age at baseline (years) | 56.39 ± 7.31 | 40–70 |
| Age at MRI scan (years) | 63.94 ± 7.32 | 46–80 |
| No. of females (%) | 3,897 (54.5) | |
| Highest educational qualification (%) | O levels/GCSE = 146 (2%) | CSE = 771 (10.8%) | A levels/AS = 398 (5.6%) NVQ/HND/HNC = 2213 (30.9%) | CU = 3624 (50.7%) | |
| Occupational status n. (%) | 0 = 1480 (20.7%) | 1 = 17 (0.2%) | 2 = 29 (0.4%) | 3 = 37 (0.5%) | 4 = 58 (0.8%) | 5 = 154 (2.2%) | 6 = 513 (7.2%) | 7 = 1046 (14.6%) | 8 = 2290 (32%) | 9 = 1528 (21.4%) | |
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| Activities | ||
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| No. (%) reporting weekly participation at | Baseline | Follow-up |
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| Leisure-time computer use | 6,340 (88.7) | 6,778 (94.8) |
| Visiting friends and family | 5,750 (80.4) | 5,874 (82.1) |
| Going to the pub or social club | 2,540 (35.5) | 2,513 (35.1) |
| Undertaking religious activities | 1,723 (24.1) | 1,770 (24.8) |
| Attending educational courses | 903 (12.6) | 775 (10.8) |
| Going to a sports club or gym | 3,852 (50.1) | 3,539 (49.5) |
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| Health and Lifestyle | Range | |
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| BMI (kg/m2) | 26.4 ± 4.01 | 16.14–55.07 |
| MAP | 99.57 ± 11.84 | 60–152.83 |
| No. (%) with ICD-10 diagnosis of Depression/Anxiety | 51 (0.71) | |
| Sleep duration (hours/night) | 7.21 ± 0.93 | 2–13 |
| Alcohol (frequency/week) | 0 = 300 (4.2%) | 1 = 499 (7%) | 2 = 664 (9.3%) | 3 = 1,837 (25.7%) | 4 = 2,183 (30.5%) | 5 = 1,669 (23.3%) | |
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| Structural MRI measures | ||
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| Total GM (volume, mm3) | 613,301.98 ± 54,614.44 | 443,926–832,927 |
| WM (volume, mm3) | 547,421.16 ± 61,214.82 | 362,561–804,641 |
| CSF (volume, mm3) | 36,479.39 ± 17,032.15 | 7,613.27–157,075 |
| WM hyperintensities (volume, mm3)* | 2,752 (4054.5) | 30–86,534 |
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| Cognitive function (n = 1,734) | ||
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| Fluid intelligence score | 7.04 ± 1.93 | 1–13 |
| Alphanumeric trail making (seconds)* | 47.9 (20.08) | 21.10–242.10 |
| Numeric trail making (seconds)* | 19.9 (6.5) | 9.40–112.90 |
| Pairs matching test (total errors)* | 6 (4) | 0–28 |
| Simple reaction time (seconds) | 0.59 ± 0.1 | 0.37–1.34 |
| No. of correct symbol-digit matches | 19.74 ± 5.14 | 2–36 |
| Backward digit span score | 6.91 ± 1.22 | 2–12 |
| Prospective memory score (No. % correct) | 1,510 (87.1%) | |
Values are Mean ± Standard deviation and N (%) for categorical variables, unless otherwise stated. *Median (IQR) reported. BMI, body mass index; BP, blood pressure; CSE, certificate of secondary education, CSF, cerebrospinal fluid; CU, college or university degree, GCSE, general certificate of secondary education; GM, gray matter; HNC, higher national certificate; HND, higher national diploma; ICD, international classification of diseases; MAP, mean arterial pressure; MRI, magnetic resonance imaging; OL, O-levels, N, number; NVQ, national vocational qualifications; WM, white matter. Occupational status was coded according to the following scale: 0 = “Unemployed/Retired/Unable to work/Student,” 1 = “Elementary Occupations,” 2 = “Process, plant and machine operatives,” 3 = “Sales and Customer Service Occupations,” 4 = “Personal Service Occupations,” 5 = “Skilled Trades Occupations,” 6 = “Administrative and Secretarial Occupations,” 7 = “Associate Professional and Technical Occupations,” 8 = “Professional Occupations,” and 9 = “Manager and Senior Officials. Alcohol intake was measured on a 5-point scale: 5 = “daily or almost daily,” 4 = “three or four times a week,” 3 = “once or twice a week,” 2 = “one to three times a month,” and 1 = “special occasions only” or 0 = “never.”