Month: October 2022

What’s the connection between flu vaccination and lower risk of Alzheimer’s Disease?

FA Manian MD, MPH, , , , , , , , , , , , , , Leave a comment

As far fetched that it may sound, there is growing evidence that flu vaccination is associated with lower risk of being diagnosed with Alzheimer’s Disease (AD).1

The most compelling evidence to date comes from a 2022 retrospective, propensity-matched study involving a nationwide sample of over 2 million U.S. adults ≥ 65 years old.1  This study found a 40% reduction in the risk of incident AD during the 4-year follow-up period when individuals receiving at least 1 dose of flu vaccine were compared to those who did not receive flu vaccination during the study period (number needed to treat-NTT 29.4). 

Despite its limitations, the results of the above study were concordant with those of several smaller studies that found an association between flu vaccination and lower risk of dementia of any cause.1-3  A 2022 meta-analysis also concluded that flu vaccination was associated with significantly lower risk (33%) of dementia among older people. Interestingly, in a study involving veterans, receipt of ≥6 doses of flu vaccines (not fewer) was associated with lower risk of dementia.4

Several hypotheses have been posited to explain the potential beneficial impact of flu vaccination on the risk of dementia, including: 1. Influenza-specific mechanisms, such as mitigation of damage secondary to influenza infection and/or epitopic similarity between influenza proteins and AD pathology; 2. Non-influenza-specific training of the innate immune system; and 3. Non-influenza-specific changes in adaptive immunity via lymphocyte-mediated cross-reactivity.1

So, in addition to its protective effect against severe influenza,5 and its association with lower risk of hospitalization for cardiac disease and stroke and reduction in death due to combined cardiovascular disease events (eg, heart attacks/strokes),  flu vaccination may be protective against AD! Who would have thought that a simple vaccine may have far reaching health benefits?

Bonus Pearl: Did you know that mice infected with non-neurotropic influenza strains have been found to have excessive microglial activation and subsequent alteration of neuronal morphology, particularly in the hippocampus, and that in APP/PS1 transgenic mice, peripheral influenza infection induces persistent elevations of amyloid- (A) plaque burden?1  Intriguing indeed!!!

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References

  1. Bukhbinder AS, Ling Y, Hasan O, et al. Risk of Alzheimer’s disease following influenza vaccination: A claims-based cohort study using propensity score matching. Journal of Alzheimer’s Disease 2022; 88:1061-1074. https://pubmed.ncbi.nlm.nih.gov/26945371/  
  2. Liu JC, Hsu YP, Kao PF, et al. Influenza vaccination reduces dementia risk in chronic kidney disease patients: A population-based cohort study. Medicine (Baltimore) 2016 95 :32868. https://pubmed.ncbi.nlm.nih.gov/26945371/
  3. Wiemken TL, Salas J, Hoft DF, et al. Dementia risk following influenza vaccination in a large veteran cohort. Vaccine 2021;39:5524-5531. https://pubmed.ncbi.nlm.nih.gov/34420785/
  4. Veronese N, Demurtas J, Smith L, et al. Influenza vaccination reduces dementia risk: A systematic review and meta-analysis. Ageing Res Rev 2022;73:101534. https://pubmed.ncbi.nlm.nih.gov/34861456/
  5. Godoy P, Romero A, Soldevila N, et al. Influenza vaccine effectiveness in reducing severe outcomes over six influenza seasons, a case-cae analysis, Spain, 2010/11 to 2015/16.  Euro Surveill 2018;23:1700732. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208006/
  6. Hosseini S, Michaelsen-Preusse K, Schughart K, et al. Long-term consequences of non-neurotropic H3N2 influenza A virus infection for the progression of Alzheimer’s Disease symptoms. Front. Cell. Neurosci 28 April 2021; https://doi.org/10.3389/fncel.2021.643650 https://www.frontiersin.org/articles/10.3389/fncel.2021.643650/full

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

What’s the connection between flu vaccination and lower risk of Alzheimer’s Disease?

My patient with choledocholithiasis presents with acute abdominal pain, bile duct dilatation and markedly elevated serum aminotransferases (AST and ALT).  Can her markedly elevated AST and ALT levels be caused by cholelithiasis with bile duct obstruction?  

FA Manian MD, MPH, , , , , , , , , , , , , Leave a comment

Although markedly increased serum alanine transaminase (ALT) and aspartate transaminase (AST) are often considered a marker for severe hepatocellular injury or necrosis (particularly when levels exceed 1000 IU/L), occasionally such elevations may also be due to isolated acute biliary duct obstruction caused by choledocholithiasis.1  

In one case series, patients  diagnosed with choledocholithiasis were found to have transient elevations in their AST/ALT (>1000 units/L) directly proportional to the degree of common bile duct dilation in the absence of any hepatocellular disease on imaging. These levels were found to rapidly fall following intervention with endoscopic retrograde cholangiopancreatography (ERCP). 2   Intriguingly, the authors of this study suggest that patients who present with severe abdominal pain associated with an acute and markedly elevated serum aminotransferase levels, are more likely to have acute biliary obstruction than hepatocellular disease.3  Several other case series have also shown similar elevations of serum aminotransferases in choledocholithiasis, with some levels reaching >2000 IU/L.4   

Several hypotheses have been proposed to explain this phenomenon, including pressure-induced damage of hepatocytes and bile salt-induced hepatocyte injury in the setting of acute biliary duct obstruction.2 Of interest, some have proposed that the gallbladder may minimize elevations in serum aminotransferases by protecting the liver from rapid increases in biliary duct pressure.  In fact, more robust elevations in aminotransferases in choledocholithiasis have been observed in those who have had cholecystectomy.4   

So even though choledocholithiasis is traditionally associated with a “cholestatic” pattern of enzyme elevations—with elevated alkaline-phosphatase, and gamma-glutamyl transferase (GGT) levels 1,3—when associated with bile duct obstruction, it  can also be associated with markedly elevated ALT and AST.  

Bonus Pearl: Did you know that when assessing for choledocholithiasis, magnetic resonance cholangiopancreatography (MRCP) is more sensitive than ultrasound (81% vs 18-74 %).4,5,6  

Contributed by Connor S. Shaw, D.O., Mercy Hospital, St. Louis, Missouri

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References  

  1. Feldman, Mark, et al. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Pathophysiology, Diagnosis, Management. Elsevier, 2021.  
  2. Tetangco, Eula Plana, et al. “Markedly Elevated Liver Enzymes in Choledocholithiasis in the Absence of Hepatocellular Disease.” Journal of Investigative Medicine High Impact Case Reports, vol. 4, no. 2, 2016, p. 232470961665109., https://doi.org/10.1177/2324709616651092. 
  3. De Angelis C, Marietti M, Bruno M, Pellicano R, Rizzetto M. Endoscopic ultrasound in common bile duct dilatation with normal liver enzymes. World J Gastrointest Endosc. 2015 Jul 10;7(8):799-805. doi: 10.4253/v7.i8.799. PMID: 26191344; PMCID: PMC4501970.
  4. Agahi, A., and A. McNair. “Choledocholithiasis Presenting with Very High Transaminase Level.” Case Reports, vol. 2012, no. nov22 2, 2012, https://doi.org/10.1136/bcr-2012-007268.
  5. Makmun, Dadang, et al. “Sensitivity and Specificity of Magnetic Resonance Cholangiopancreatography versus Endoscopic Ultrasonography against Endoscopic Retrograde Cholangiopancreatography in Diagnosing Choledocholithiasis: The Indonesian Experience.” Clinical Endoscopy, vol. 50, no. 5, 2017, pp. 486–490., https://doi.org/10.5946/ce.2016.159.
  6. Ferri, João Victor, et al. “Níveis Elevados De Transaminases Em Um Caso De Coledocolitíase: A Importância Do Reconhecimento Deste Padrão.” Revista De Medicina, vol. 96, no. 2, 2017, p. 131., https://doi.org/10.11606/issn.1679-9836.v96i2p131-133.   

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

My patient with choledocholithiasis presents with acute abdominal pain, bile duct dilatation and markedly elevated serum aminotransferases (AST and ALT).  Can her markedly elevated AST and ALT levels be caused by cholelithiasis with bile duct obstruction?