Table 1.
Demographics, PET, cognitive and sleep summary information (mean ± SD)
| Variable | Aβ+ group (N = 31) | Aβ- group (N = 31) |
|---|---|---|
| Age (years) | 75.97 ± 3.81 | 75.26 ± 6.08 |
| Sex (% Female) | 68 | 55 |
| BMI | 25.65 ± 3.91a | 24.74 ± 4.16 |
| Education (years) | 16.65 ± 2.06 | 17.19 ± 1.49 |
| Global PiB DVR | 1.34 ± 0.26 | 1.02 ± 0.03*** |
| Time interval between PET and PSG sessions (years) | 0.63 ± 0.06 | 0.62 ± 0.08 |
| Total sleep time (min) | 325 ± 72 | 330 ± 63 |
| NREM2 time (min) | 178 ± 57 | 192 ± 60 |
| NREM3 time (min) | 64 ± 53 | 52 ± 36 |
| REM time (min) | 48 ± 19 | 48 ± 21 |
| WASO (min) | 121 ± 64 | 121 ± 53 |
| NREM SWA (relative delta power) | 0.73 ± 0.07 | 0.68 ± 0.08* |
| MMSE | 29.13 ± 1.06 | 28.90 ± 1.19 |
| Item memory (d-prime) | 0.56 ± 0.34b | 0.54 ± 0.41 |
| Associative memory (d-prime) | 0.51 ± 0.37b | 0.46 ± 0.38 |
| Memory composite score (z-score) | -0.11 ± 0.78 | -0.13 ± 0.93 |
In line with previous findings [27], NREM SWA, defined as NREM relative delta power in the 0.5 to 4 Hz frequency range, was significantly higher in the Aβ+ group compared to the Aβ- group (p = 0.01, see section ‘Association between Aβ burden and spectral power in the delta frequency range’ and Figure S1 in Additional file 1 [27, 31–33])
BMI Body Mass Index, PiB DVR Pittsburgh compound B Distribution Volume Ratio, PET Positron Emission Tomography, PSG Polysomnography, NREM Non-rapid eye movement, WASO Wake after sleep onset, SWA Slow wave activity, MMSE Mini-Mental State Examination
*p < 0.05
***p < 0.001
aN = 30
bN = 28