We conducted a cohort study with a nested case-control analysis using the GOLD and Aurum data sets from the United Kingdom Clinical Practice Research Datalink (CPRD). The CPRD is a large primary care database enrolling >50 million patients across 1900 publicly funded UK practices, and it is broadly representative of the general population for critical variables such as age, sex, and ethnicity [23].
Conclusion:
Our results do not support a role for vaccinations in the prevention of dementia. Indeed, we did not observe a decreased risk of dementia with common vaccines overall or with individual vaccines (apart from marginal effects with shingles and diphtheria vaccines). Design-specific aspects, such as the application of a nested case-control analysis that eliminated immortal time bias and the use of a 2-year lag period that minimized protopathic and early detection bias, may have accounted for the discrepancy between our results and those from previous studies.
The observed increase in the risk was unexpected. Given the lack of any biological rationale linking vaccinations to an increased risk of dementia, and considering the totality of our findings, we deem unmeasured confounding and late detection bias to be the most plausible explanations.
the recording of dementia in the CPRD has been shown to be accurate [26].
Overall, our large population-based study showed no decreased risk of dementia associated with routinely administered vaccines.
[26]
McGuinness LA, Warren-Gash C, Moorhouse LR, Thomas SL. The validity of dementia diagnoses in routinely collected electronic health records in the United Kingdom: a systematic review. Pharmacoepidemiol Drug Saf 2019; 28:244–55.
Can someone help me understand this? How does this mean a 50% increase in dementia?
Results: Common vaccines were associated with an increased risk of dementia (OR, 1.38 [95% CI, 1.36-1.40]), compared with no exposure.
Edit: Adding Grok's feedback
The study at https://pubmed.ncbi.nlm.nih.gov/36542511/ is titled "Common Vaccines and the Risk of Incident Dementia: A Population-based Cohort Study," published in the Journal of Infectious Diseases in 2023 (PMID: 36542511). It is a large population-based cohort study (using a nested case-control design) of dementia-free adults aged ≥50 years in the UK's Clinical Practice Research Datalink, followed from 1988 to 2018.
The researchers investigated whether exposure to common vaccines (administered more than 2 years before dementia diagnosis/index date) was linked to dementia risk, compared to no exposure during the study period.
Key quantitative finding on increased dementia risk:
Common vaccines were associated with a 38% increased risk of incident dementia, with an adjusted odds ratio (OR = 1.38, 95% confidence interval [CI]: 1.36–1.40) compared to no exposure.
However, the authors emphasize that this observed increase is not causal. Sensitivity analyses showed attenuation (weakening) of the association when accounting for potential biases:
With a 10-year lag period (exposure >10 years before index date): OR = 1.20 (95% CI: 1.18–1.23), a 20% increased risk.
When using active comparators like prostate cancer screening participation: OR = 1.19 (95% CI: 1.11–1.27).
Breast cancer screening comparator did not attenuate it as much (OR = 1.37, 95% CI: 1.30–1.45).
The study's conclusion states that common vaccines were not associated with a decreased risk of dementia (contrary to some prior observational suggestions). The apparent increased risk was likely explained by unmeasured confounding (e.g., healthier people more likely to get vaccinated and screened) and detection bias (vaccinated individuals may have more healthcare contact, leading to earlier dementia diagnosis).
No hazard ratios (HRs) were directly reported in the abstract (it used ORs due to the case-control matching), and the study does not claim vaccines truly cause higher dementia rates—rather, the raw association is confounded. This contrasts with some other studies on specific vaccines (e.g., influenza or herpes zoster) that have reported protective associations against dementia.
Full text PDF
https://academic.oup.com/jid/article/227/11/1227/6948438?login=false
Archived Link: https://archive.ph/lPEcQ
Catbox link to not give them so much traffic https://files.catbox.moe/lokjgf.pdf
50 million people not 13 million
Conclusion:
[26]
McGuinness LA, Warren-Gash C, Moorhouse LR, Thomas SL. The validity of dementia diagnoses in routinely collected electronic health records in the United Kingdom: a systematic review. Pharmacoepidemiol Drug Saf 2019; 28:244–55.
https://onlinelibrary.wiley.com/doi/10.1002/pds.4669
Thank you!
Can someone help me understand this? How does this mean a 50% increase in dementia?
Edit: Adding Grok's feedback
The study at https://pubmed.ncbi.nlm.nih.gov/36542511/ is titled "Common Vaccines and the Risk of Incident Dementia: A Population-based Cohort Study," published in the Journal of Infectious Diseases in 2023 (PMID: 36542511). It is a large population-based cohort study (using a nested case-control design) of dementia-free adults aged ≥50 years in the UK's Clinical Practice Research Datalink, followed from 1988 to 2018.
The researchers investigated whether exposure to common vaccines (administered more than 2 years before dementia diagnosis/index date) was linked to dementia risk, compared to no exposure during the study period.
Key quantitative finding on increased dementia risk:
However, the authors emphasize that this observed increase is not causal. Sensitivity analyses showed attenuation (weakening) of the association when accounting for potential biases:
The study's conclusion states that common vaccines were not associated with a decreased risk of dementia (contrary to some prior observational suggestions). The apparent increased risk was likely explained by unmeasured confounding (e.g., healthier people more likely to get vaccinated and screened) and detection bias (vaccinated individuals may have more healthcare contact, leading to earlier dementia diagnosis).
No hazard ratios (HRs) were directly reported in the abstract (it used ORs due to the case-control matching), and the study does not claim vaccines truly cause higher dementia rates—rather, the raw association is confounded. This contrasts with some other studies on specific vaccines (e.g., influenza or herpes zoster) that have reported protective associations against dementia.
Oh yes. Thanks.