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Long-term systemic inflammation and cognitive impairment in a population-based cohort
Wichmann MA, Cruickshanks KJ, Carlsson CM, Chappell R, Fischer ME, Klein BE, Klein R, Tsai MY et al.. Journal of the American Geriatrics Society, 2014-08-14
Topic: Brain imaging, connectivity and assessment
Objectives Evidence suggests inflammation is associated with cognitive impairment, but previous epidemiological studies have reported conflicting results. Design Prospective population-based cohort. Setting Epidemiology of Hearing Loss Study participants. Participants Individuals without cognitive impairment in 1998-2000 (N = 2,422; 1,947 with necessary data). Measurements Cognitive impairment (Mini-Mental State Examination score <24 or diagnosis of dementia) was ascertained in 1998-2000, 2003-2005, and 2009-2010. Serum C-reactive protein (CRP) and interleukin-6 (IL-6) were measured in 1988-1990, 1998-2000, and 2009-2010; tumor necrosis factor-alpha was measured from 1998-2000. Results Participants with high CRP in 1988-1990 and 1998-2000 had lower risk of cognitive impairment than those with low CRP at both time points (hazard ratio (HR) = 0.46, 95% confidence interval (CI) = 0.26-0.80). Risk did not differ according to 10-year IL-6 profile or baseline inflammation category in the whole cohort. In sensitivity analyses restricted to statin nonusers, those with high IL-6 at both times had greater risk of cognitive impairment than those with low IL-6 at both times (HR = 3.35, 95% CI = 1.09-10.30). In secondary analyses, each doubling of IL-6 change over 20 years was associated with greater odds of cognitive impairment in 2009-2010 in the whole cohort (odds ratio (OR) = 1.40, 95% CI = 1.04-1.89), whereas a doubling of CRP change over 20 years was associated with cognitive impairment only in statin nonusers (OR = 1.32, 95% CI = 1.06-1.65). Conclusion With data collected over 20 years, this study demonstrated greater likelihood of cognitive impairment in individuals with repeated high or increasing IL-6. The inconsistent CRP findings may reflect effects of statin medications, survival effects, or adverse effects associated with chronically low CRP. Further studies of long-term inflammation and cognitive impairment are needed.
Key findings
- Objectives Evidence suggests inflammation is associated with cognitive impairment, but previous epidemiological studies have reported conflicting results.
- Results Participants with high CRP in 1988-1990 and 1998-2000 had lower risk of cognitive impairment than those with low CRP at both time points (hazard ratio (HR) = 0.46, 95% confidence interval (CI) = 0.26-0.80).
- In secondary analyses, each doubling of IL-6 change over 20 years was associated with greater odds of cognitive impairment in 2009-2010 in the whole cohort (odds ratio (OR) = 1.40, 95% CI = 1.04-1.89), whereas a doubling of CRP change over 20 years was associated with cognitive impairment only in statin nonusers (OR = 1.32, 95% CI = 1.06-1.65).
- Conclusion With data collected over 20 years, this study demonstrated greater likelihood of cognitive impairment in individuals with repeated high or increasing IL-6.
- The inconsistent CRP findings may reflect effects of statin medications, survival effects, or adverse effects associated with chronically low CRP.
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Study details
- Participants2,422
- Effect sizeHR = 3.35; OR = 1.32
- Evidence strengthModerate
How this study scored 55/100
Published in a peer-reviewed journal. Scored zero for study design and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 32 of the 58 points we could judge it on, which is 55 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Journal of the American Geriatrics Society) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| 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 | 2014 — within 20 year(s) of the newest study here |
| Sample size | 3 / 4 | 2,422 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 | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 25123210) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 32 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 32 of the 58 points we could judge it on is 55 out of 100. |
| Total | 55 / 100 | — |
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APA 7th
Wichmann, M. A., Cruickshanks, K. J., Carlsson, C. M., Chappell, R., Fischer, M. E., Klein, B. E., et al. (2014). Long-term systemic inflammation and cognitive impairment in a population-based cohort. Journal of the American Geriatrics Society. https://doi.org/10.1111/jgs.12994
Vancouver
Wichmann MA, Cruickshanks KJ, Carlsson CM, Chappell R, Fischer ME, Klein BE, et al. Long-term systemic inflammation and cognitive impairment in a population-based cohort. Journal of the American Geriatrics Society. 2014. doi:10.1111/jgs.12994. PMID: 25123210.
BibTeX
@article{wichmann2014-25123210,
author = {Wichmann, M. A. and Cruickshanks, K. J. and Carlsson, C. M. and Chappell, R. and Fischer, M. E. and Klein, B. E. and Klein, R. and Tsai, M. Y. and others},
title = {{Long-term systemic inflammation and cognitive impairment in a population-based cohort}},
journal = {Journal of the American Geriatrics Society},
year = {2014},
doi = {10.1111/jgs.12994},
pmid = {25123210},
url = {https://doi.org/10.1111/jgs.12994}
}
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