Table I.
Sample characteristics in different age groups
| Age group (yr) | No. subjects | No. subjects in scanning sitea 1/2/3 | Females (%) | Ethnicityb (%) | Educationc mean (SD) |
|---|---|---|---|---|---|
| 19–29 | 88 | 30/40/18 | 40 (45) | 69/1/18/12 | 4.56 (0.97) |
| 30–39 | 103 | 58/24/21 | 59 (57) | 76/3/15/6 | 4.76 (0.61) |
| 40–49 | 88 | 49/28/11 | 44 (50) | 85/1/9/5 | 4.14 (1.15) |
| 50–59 | 83 | 55/25/3 | 31 (37) | 83/4/7/6 | 3.81 (1.27) |
| 60–69 | 123 | 77/39/7 | 45 (37) | 83/3/10/4 | 3.51 (1.54) |
| 70–79 | 54 | 31/17/6 | 18 (33) | 89/2/6/3 | 3.46 (1.55) |
| 80–86 | 8 | 6/1/1 | 5 (63) | 100/0/0/0 | 3.50 (2.07) |
| Total | 547 | 306/174/67 | 242 (44) | 81/2/11/6 | 4.05 (1.03) |
a
Three separate subsamples from different scanning sites in London: Guys Hospital Philips 1.5T/Institute of Psychiatry General Electric 1.5T/Hammersmith Hospital with a Philips 3T scanner.
b
Percentage ratio of different ethnic groups in the whole IXI sample: Caucasian/Black/Asian/Other.
c
Education levels: 1 = no qualifications; 2 = O‐levels, GCSEs, or CSE; 3 = A‐levels; 4 = further education; 5 = university or polytechnic degrees.
SD, standard deviation.