Table 3.
Summary of case studies
| Study | Objective | Country | Type of HRT | Sample size | Attrition | Method | Statistical Results | Conclusion |
|---|---|---|---|---|---|---|---|---|
| Henderson et al (2005)9 | Preventing and delaying onset of Alzheimer's disease | USA | Oestrogen (any form) | 971 | 0 (0%) | Current/former user or never used via history | Relative risk 0.64 (odds ratio 0.47 [95% CI 0.35–0.63]) | Oestrogen containing HRT may prevent and delay onset of Alzheimer's disease |
| Seshadri et al (2001)14 | Reducing risk of Alzheimer's disease | UK | Oral oestrogen with or without progestin or transdermal oestrogen | 280 | 0 (0%) | Medical records and medical history | Relative risk 1.18 (odds ratio 1.08 [95% CI 0.56–2.10]) | No reduction in risk of developing Alzheimer's disease in post-menopausal use of oestrogen replacement therapy |
| Imtiaz et ala (2017)15 | Reducing risk of developing Alzheimer's disease | Finland | Oral, transdermal or combination oestrogen only; progesterone only, combined or mixed | 230 580 | 0 (0%) | Medical records | Relative risk 1.05 (odds ratio 1.06 [95% CI 1.02–1.10]) | No association between HRT and risk of Alzheimer's disease |
| Brenner et al (1994)18 | Reducing risk of developing Alzheimer's disease | USA | Oral conjugated oestrogens, diethyistilbestrol tablets, ethinylestradiol tablets, vaginal conjugated oestrogens, dlenestrol vaginal cream, other vaginal oestrogens | 236 | 9 (3.8%) | Medical records and medical history | Relative risk 1.01 (odds ratio 1.10 [95% CI 0.6–1.8]) | No evidence that oestrogen replacement therapy has an effect on risk of Alzheimer's disease |
| Slooter et al (1999)19 | Prevention of Alzheimer's disease | The Netherlands | Not collectedb | 228 | Undisclosed | Information collected from the next of kin via interview | Relative risk 0.47 (odds ratio 0.34 [95% CI 0.12–0.94]) | Oestrogen use is beneficial to Alzheimer's disease with early onset |
| Kim et al (2021)20 | Reducing risk of Alzheimer's disease | USA | Oral or transdermal oestrogen | 379 352 | 1998 (0.53%) | Medical insurance records | Relative risk 0.43 (odds ratio 0.43 [95% CI 0.41–0.45]) | HRT is associated with reduced risk of developing Alzheimer's disease |
| Henderson et al (1994)21 | Reducing risk of Alzheimer's disease | USA | Oral oestrogen | 235 | 0 (0%) | Medical history, autopsy and post-mortem confirmation | Relative risk 0.58 (odds ratio 0.33 [95% CI 0.14–0.76]) | Post-menopausal oestrogen replacement therapy may decrease risk of Alzheimer's disease. Cognitive performance may be improved with oestrogen replacement therapy |
| Paganini-Hill and Henderson (1996)26 | Preventing and delaying onset of Alzheimer's disease | USA | Oral CEE (1.25 mg), oral plus injection and/or cream, injection and/or cream | 1446 | 0 (0%) | Questionnaire, medical history and records from death certificates | Relative risk 0.73 (odds ratio 0.65 [95% CI 0.49–0.88]) | Oestrogen replacement therapy may prevent or delay onset of Alzheimer's disease in post-menopausal women |
| Roberts et al (2006)27 | Reducing risk of Alzheimer's disease | USA | Oral or transdermal oestrogen | 528 | 38 (7.2%) | Medical records | Relative risk 1.04 (odds ratio 1.10 [95% CI 0.63–1.93]) | No association between oestrogen replacement therapy and Alzheimer's disease |
| Pourhadi et al (2021)28 | Reducing risk of developing Alzheimer's disease | Denmark | Vaginal oestrogen | 50 314 | Undisclosed | Medical records | Relative risk 0.93 (odds ratio 0.92 [95% CI 0.86–0.99]) | No association between vaginal oestrogen therapy with Alzheimer's disease |
| Waring et al (1999)29 | Reducing risk of Alzheimer's disease | USA | Oestrogen (any form) | 444 | Undisclosed | Medical records and autopsy reports | Relative risk 0.79 (odds ratio 0.65 [95% CI 0.40–1.06]) | Oestrogen replacement therapy reduces risk of Alzheimer's disease in post-menopausal women |
HRT, hormone replacement therapy; CEE, conjugated equine oestrogen.
a.
Note that this study is a different study from the Imtiaz et al25 cohort study.
b.
Unable to contact authors for further clarification.