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High total cholesterol levels in late life associated with a reduced risk of dementia
Mielke MM, Zandi PP, Sjögren M, Gustafson D, Ostling S, Steen B, Skoog I.. Neurology, 2005-05-01
Topic: Risk, prevention and care in population studies
Objective To examine the longitudinal association between plasma total cholesterol and triglyceride levels and incident dementia. Methods Neuropsychiatric, anthropometric, laboratory, and other assessments were conducted for 392 participants of a 1901 to 1902 birth cohort first examined at age 70. Follow-up examinations were at ages 75, 79, 81, 83, 85, and 88. Information on those lost to follow-up was collected from case records, hospital linkage system, and death certificates. Cox proportional hazards regression examined lipid levels at ages 70, 75, and 79 and incident dementia between ages 70 and 88. Results Increasing cholesterol levels (per mmol/L) at ages 70 (hazard ratio [HR] 0.77, 95% CI: 0.61 to 0.96, p = 0.02), 75 (HR 0.70, CI: 0.52 to 0.93, p = 0.01), and 79 (HR 0.73, CI: 0.55 to 0.98, p = 0.04) were associated with a reduced risk of dementia between ages 79 and 88. Examination of cholesterol levels in quartiles showed that the risk reduction was apparent only among the highest quartile at ages 70 (8.03 to 11.44 mmol/L [311 to 442 mg/dL]; HR 0.31, CI: 0.11 to 0.85, p = 0.03), 75 (7.03 to 9.29 mmol/L [272 to 359 mg/dL]; HR 0.20, CI: 0.05 to 0.75, p = 0.02), and 79 (6.82 to 9.10 mmol/L [264 to 352 mg/dL]; HR 0.45, CI: 0.17 to 1.23, p = 0.12). Triglyceride levels were not associated with dementia. Conclusions High cholesterol in late life was associated with decreased dementia risk, which is in contrast to previous studies suggesting high cholesterol in mid-life is a risk factor for later dementia. The conflicting results may be explained by the timing of the cholesterol measurements in relationship to age and the clinical onset of dementia.
Key findings
- Results Increasing cholesterol levels (per mmol/L) at ages 70 (hazard ratio [HR] 0.77, 95% CI: 0.61 to 0.96, p = 0.02), 75 (HR 0.70, CI: 0.52 to 0.93, p = 0.01), and 79 (HR 0.73, CI: 0.55 to 0.98, p = 0.04) were associated with a reduced risk of dementia between ages 79 and 88.
- Examination of cholesterol levels in quartiles showed that the risk reduction was apparent only among the highest quartile at ages 70 (8.03 to 11.44 mmol/L [311 to 442 mg/dL]; HR 0.31, CI: 0.11 to 0.85, p = 0.03), 75 (7.03 to 9.29 mmol/L [272 to 359 mg/dL]; HR 0.20, CI: 0.05 to 0.75, p = 0.02), and 79 (6.82 to 9.10 mmol/L [264 to 352 mg/dL]; HR 0.45, CI: 0.17 to 1.23, p = 0.12).
- Triglyceride levels were not associated with dementia.
- Conclusions High cholesterol in late life was associated with decreased dementia risk, which is in contrast to previous studies suggesting high cholesterol in mid-life is a risk factor for later dementia.
- The conflicting results may be explained by the timing of the cholesterol measurements in relationship to age and the clinical onset of dementia.
Why it matters
In this birth cohort followed to age 88, higher total cholesterol levels in late life were associated with a reduced risk of dementia, while triglyceride levels showed no association. This observational finding does not mean high cholesterol is protective or that raising cholesterol prevents dementia, and it contrasts with cholesterol's known cardiovascular risks.
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Study details
- Study designlongitudinal study
- Participants392
- Effect sizeHR 0.70; HR 0.73; HR 0.31
- Evidence strengthModerate
How this study scored 70/100
Published in a leading specialty journal, and it is a longitudinal study following the same people over time. Scored zero for randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| Study design | 7 / 12 | A longitudinal study following the same people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2005 — older than 20 years, still counted |
| Sample size | 2 / 4 | 392 participants |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 6 / 7 | Cited 412 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 17.9 citations a year over 23 year(s) since 2005 |
| Impact for its field and year | 4 / 6 | Cited 11.6× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 29 other studies in this library |
| Still being cited | 2 / 4 | Cited 42 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Ingmar Gr. Skoog: h-index 105 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | Johns Hopkins University: institution h-index 2,306 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 4 institution(s) in 3 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 15911792) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 70 / 100 | — |
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Read the original
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. The record names 7 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
Mielke, M. M., Zandi, P. P., Sjögren, M., Gustafson, D., Ostling, S., Steen, B., et al. (2005). High total cholesterol levels in late life associated with a reduced risk of dementia. Neurology. https://doi.org/10.1212/01.wnl.0000161870.78572.a5
Vancouver
Mielke MM, Zandi PP, Sjögren M, Gustafson D, Ostling S, Steen B, et al. High total cholesterol levels in late life associated with a reduced risk of dementia. Neurology. 2005. doi:10.1212/01.wnl.0000161870.78572.a5. PMID: 15911792.
BibTeX
@article{mielke2005-15911792,
author = {Mielke, M. M. and Zandi, P. P. and Sjögren, M. and Gustafson, D. and Ostling, S. and Steen, B. and Skoog, I.},
title = {{High total cholesterol levels in late life associated with a reduced risk of dementia}},
journal = {Neurology},
year = {2005},
doi = {10.1212/01.wnl.0000161870.78572.a5},
pmid = {15911792},
url = {https://doi.org/10.1212/01.wnl.0000161870.78572.a5}
}
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