Table 1.
Sample demographics stratified by the degree of sleep symptomatology
| Sleep symptomatology* | |||||
|---|---|---|---|---|---|
| Overall | None | Moderate | High | p | |
| Variable | (N = 1,413) | (n = 742) | (n = 351) | (n = 320) | |
| Age, years | 57.2 (7.1) | 57.5 (7.2) | 57.1 (7.3) | 56.6 (6.7) | 0.14 |
| BMI, kg/m2 | 26.4 (5.5) | 26.0 (4.9) | 26.6 (6.1) | 27.2 (6.1) | 0.008 |
| Education, years | 16.1 (3.4) | 16.2 (3.4) | 16.1 (3.4) | 15.7 (3.4) | 0.13 |
| Female, N (%) | 1,088 (77) | 564 (76) | 267 (77) | 257 (80) | 0.32 |
| Depressive symptoms, HADS score | 2.8 (2.5) | 2.1 (2.1) | 3.2 (2.7) | 3.9 (2.9) | <0.0001 |
| Anxiety symptoms, HADS score | 3.3 (3.0) | 2.5 (2.5) | 3.7 (2.9) | 4.8 (3.4) | <0.0001 |
| Current smoker, N (%) | 13 (1) | 4 (1) | 3 (1) | 6 (2) | 0.11 |
| History of type II diabetes, N (%) | 45 (3) | 22 (3) | 12 (3) | 11 (3) | 0.88 |
| Hypertension, N (%) | 269 (19) | 141 (19) | 57 (16) | 71 (22) | 0.14 |
| First-degree family history of dementia, N (%) | 764 (54) | 402 (54) | 185 (52) | 177 (55) | 0.79 |
| Second-degree family history of dementia, N (%) | 619 (44) | 320 (43) | 153 (44) | 146 (46) | 0.75 |
| APOE ε4 carrier, N (%)† | 250 (33) | 137 (35) | 68 (34) | 45 (29) | 0.40 |
| PSQI, global score | 5.0 (2.8) | 3.1 (1.4) | 5.9 (2.4) | 8.2 (2.3) | <0.0001 |
| ESS, total score | 5.0 (3.3) | 4.3 (2.6) | 5.3 (3.5) | 6.1 (3.9) | <0.0001 |
| ISI, total score | 5.3 (3.9) | 2.9 (2.1) | 6.1 (3.3) | 10.3 (2.2) | <0.0001 |
All values are presented as mean (SD) unless stated otherwise; chi-square tests were used to test differences between groups for categorical variables, and analysis of variance was used to test differences between groups for continuous variables. BMI, body mass index; HADS, Hospital Anxiety and Depression Scale; PSQI, Pittsburgh Sleep Quality Index; ESS, Epworth Sleepiness Scale; ISI, Insomnia Severity Index.
*None, normal scores on the PSQI, ISI, and ESS; Moderate, abnormal sleep on one of the sleep questionnaires; High, abnormal sleep on at least two of the three sleep questionnaires.
†Sample size with known APOE status = 754.