Shingles Shot and Dementia: Could one vaccine protect your brain?
Shingles Shot and Dementia: Could one vaccine protect your brain?  
Podcast: Normal Curves: Sexy Science, Serious Statistics
Published On: Mon Nov 03 2025
Description: What do chickenpox and shingles have to do with your brain? This week, we dig into two 2025 headline-grabbing studies that link the shingles shot to lower dementia rates. We start in Wales, where a birthday cutoff turned into the perfect natural experiment, and end in the U.S. with a multi-million-person megastudy. Featuring bias-variance Goldilockses, Fozzy-the-Bear regression discontinuities, a Barbie-versus-Oppenheimer showdown for propensity scores – and the hottest rebrand of inverse-probability weighting you’ll ever hear.Statistical topicsAbsolute vs. relative riskBias–variance tradeoffCausal inferenceCensoringConfoundingFuzzy regression discontinuity designHealthy-user biasInverse probability of treatment weighting (IPTW)Longitudinal studyNatural experimentNegative controlsOptimal bandwidthPropensity scoresSelection biasSubgroup analysisTriangular kernel weightsMethodological morals“Propensity scores are the lipstick you put on observational pigs.”“Natural experiments are a hot flirtation date with causality.”ReferencesEyting M, Xie M, Michalik F, Heß S, Chung S, Geldsetzer P. A natural experiment on the effect of herpes zoster vaccination on dementia. Nature. 2025 May;641(8062):438-446. doi: 10.1038/s41586-025-08800-x. Epub 2025 Apr 2. PMID: 40175543; PMCID: PMC12058522.Polisky V, Littmann M, Triastcyn A, et al. Varicella-zoster virus reactivation and the risk of dementia. Nat Med. Published online October 6, 2025. doi:10.1038/s41591-025-03972-5Sainani KL. Propensity scores: uses and limitations. PM&R 2012; 4:693-97.Detailed Show Notes PageKristin and Regina’s online courses: Demystifying Data: A Modern Approach to Statistical Understanding  Clinical Trials: Design, Strategy, and Analysis Medical Statistics Certificate Program  Writing in the Sciences Epidemiology and Clinical Research Graduate Certificate Program Programs that we teach in:Epidemiology and Clinical Research Graduate Certificate Program Find us on:Kristin -  LinkedIn & Twitter/XRegina - LinkedIn & ReginaNuzzo.com(00:00) - Intro and first gratuitous mention of sex (03:56) - What are shingles, chickenpox, and the vaccines against them? (12:30) - Fun facts about the varicella zoster and herpes viruses (18:00) - A natural experiment in Wales (21:54) - What is the Goldilocks optimal bandwidth? (26:17) - Fuzzy regression discontinuity design demystified (32:43) - Shingles vaccine vs dementia showdown (34:13) - Absolute risk reduction paradox (37:44) - Effects for men and women differ (41:07) - A giant longitudinal study (47:51) - Propensity scores demystified via Barbie and Oppenheimer (53:55) - Using propensity scores to make matches (58:08) - Inverse probability of treatment weighting demystified via more Barbenheimer (01:02:27) - Attempts to rename IPTW for TikTok (01:05:59) - Longitudinal study results (01:10:00) - Smooch ratings and methodological morals: pigs and hot dates