Table 1.
Characteristics of studies included in the final review
| Variables | Groups | Dlugaj et al. (2014) [24] | Guarnieri et al. (2012) [26] | Kim et al. (2011) [27] | Osorio et al. (2015) [2] | Wilson et al. (2014) [28] |
|---|---|---|---|---|---|---|
| Referral Population | – | General population (HNR cohort); age 45–75 yrs. | Neurology clinic; age > 60 years | General practitioner clinic (Public health centre); age > 60 years | Multiple clinics (ADNI cohort); age 55–90 yrs. | Neurology clinic; age > 50 years |
| Study design | – | Cross-sectional | Cross-sectional | Cross-sectional | Retrospective Cohorta | Cross-sectional |
| Study country | – | Germany | Italy | South Korea | USA and Canada | Australia |
| MCI diagnosis criteria | – | Petersen (2004) [6] Winblad (2004) [8] | Winblad (2004) [8] | Petersen (1999) [4] | Petersen (2005) [7] | Petersen (2005) [7] |
| OSA diagnosis method | – | ApneaLink™ | History of snoring or sleep apneas & high risk on Berlin Questionnaire | PSG | “Patient reported OSA, followed by physician assessment of diagnosis based on patients’ medical history” | PSG |
| OSA diagnosis criteria | – | AHI ≥ 15 events/hour | NA | AHI ≥ 5 events/hour | NR | AHI ≥ 5 events/hour |
| OSA AHI Indicesb | – |
A: ≥80%, ≥10s H: 50–80%, ≥10s OD: NR |
NA |
A: ≥100%, ≥10s H: ≥50%, ≥10s OD: 3% (or arousal) |
NR |
A: ≥100%, ≥10s H: ≥50%, ≥10s OD: 3% (or arousal) |
| Number of subjects | MCI | 230 | 138 | 30 | 402 | 37 |
| aMCI | 120 | NR | NR | 402 | 10 | |
| naMCI | 110 | 0 | 27 | |||
| Controls | 676 | – | 30 | 607 | 37 | |
| Number of males, n (%) | MCI | 919 (51%) | 50% | 9 (30%) | – | NR |
| Controls | – | 9 (30%) | ||||
| Age (years), mean ± SD | MCI | 63.79 ± 7.45 | 73 ± 9c | 67.97 ± 4.09 | – | 65.5 ± 9.0 |
| Controls | – | 67.37 ± 3.75 | 63.5 ± 8.7 | |||
| BMI (kg/m2), mean ± SD | MCI | 28.06 ± 4.38 | NR | 24.40 ± 3.28 | – | 27.6 ± 5.5 |
| Controls | 24.49 ± 2.75 | 27.1 ± 4 | ||||
| Comorbidities (major) | – | DM (18%), HTN (36%), CAD (7%) | NR | NR | – | NR |
| Education (years), n (%) or mean ± SD | MCI | ≤10: 167 (9%); 11–13: 1002 (56%); ≥14: 624 (35%) | 8.2 ± 4.2c | 6.80 ± 4.67 | – | NR |
| Controls | – | 7.90 ± 5.11 | – | NR | ||
| AHI (events/hour) | MCI | 11.5 ± 11.43 | NR | 13.41 ± 11.61 | NR | 16.4 ± 16d |
| Controls | 15 ± 13.56 | 11.9 ± 10d | ||||
| APOE positive (%) | MCI | 445 (25%) | NR | NR | – | NR |
| Controls | ||||||
| Mini Mental Status Exam, mean ± SD | MCI | NR | 27 ± 2c | NR | NR | 28.1 ± 1.5 |
| Controls | – | 29.2 ± 1.1 |
Abbreviations: A apnea, ADNI Alzheimer’s disease Neuroimaging Initiative, AHI apnea-hypopnea index, APOE Apolipoprotein E, BMI body mass index, CAD coronary artery disease, DM diabetes mellitus, HNR Heinz Nixdorf Recall, HTN hypertension, H hypopnea, MCI mild cognitive impairment, NA not applicable, NR not reported, OD oxygen desaturation, OSA obstructive sleep apnea, PSG polysomnography, SD standard deviation
aData to calculate prevalence and/or odds ratio were provided by the study authors and were taken from baseline measurements of OSA and MCI (cross-sectional)
bThe percentage drop of airflow from baseline for 10 s or more with or without oxygen desaturation
cValues estimated from a bar-graph
dAHI data was available on 24 out of the 37 subjects with MCI and 25 out of the 37 control subjects