In a powerful natural experiment using Australia’s health data, the researchers found that the selection of the vaccine for the vaccine can reduce dementia diagnoses, enhancing the hypothesis of preventive brain health strategies.
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In a recent study published in Jama (The Journal of the American Medical Association)An international team of researchers determined whether the eligibility for the vaccination of herpes zoster (Hz) (which causes pebble vaccination) on the basis of the date of birth has affected the likelihood of a new dementia (memory loss problems).
Background
Dementia affects over 55 million people worldwide, presenting a growing public health crisis. While age remains the strongest risk factor, infections can also play a role. An insufficient link is between Hz and dementia. Hz results from the reactivation of the Varicella Zoster, a neurotropic virus that can affect the central nervous system. Vaccination against HZ can not only prevent pebbles but also the lowest risk of dementia, possibly through immunological configuration. A previous quasi -experimentation in Wales has found this union, but reproduction is essential in various populations and health systems. Further investigations are needed to validate these findings worldwide.
For the study
This study used a quasi -experimental design using primary care data of 65 general practices across Australia, facilitated by Pencs Platform Health Informatics. The analysis took advantage of a natural elimination cut created by the National Immunization Program, which began to provide the live Hz (Zostavax) vibrant vaccine (Zostavax) on November 1, 2016 to people aged 70 to 79 years. Eligibility was determined by the date of birth: people born on or after November 2, 1936 were eligible, while those born before were not. This arrangement allowed the comparison between groups that were almost identical to the health of age and basic line, which differ mainly in vaccine access.
Patient records included historical diagnosis, immune effects, recipes and demographic details. Birth dates were coded in the week and all diagnoses, including dementia, were identified using open -type text fields provided by general doctors. Patients aged 50 years and over November 1, 2016 and with at least one clinical visit between 1993 and 2024 were included.
The main result was the first recorded diagnosis of dementia during a 7.4 -year monitoring period. The main report was the eligibility for Hz vaccination based on the date of birth. The statistical analysis focused on discontinuity of reflux (RD), comparing people born shortly before and after the eligibility threshold. This method controls both the observed and the non -observed variables, assuming that there are no abrupt changes other than the vaccination state. Secondary analyzes used time models for examination, including accelerated failure time and Kaplan-Meier survival analysis, along with multiple bandwidth controls and modeling strategies. All analyzes were conducted using the statistical software R.
It is important to note that the result measured in this study is for the eligibility for Hz vaccination, not for confirmed vaccine receipt, because the vaccination status is likely to undergo a deterioration in primary care data. Because of this subject, the authors of the study did not attempt to appreciate the effect of receiving the vaccine, as this could overestimate the results.
In addition, the study population comes from practices that have agreed to participate and use the Penss platform, so the data are not fully representative of all Australian primary care patients. The assessment of the results is also “local”, applying more clearly to people about 79 to 80 years of age when the Hz vaccination program began.
The protective effect observed in this study is specifically related to the living weakened HZ vaccine (Zostavax), as the newest recombinant vaccine was not widely used in Australia during the study period.
Results
Data from 101,219 patients were analyzed, focusing on 18,402 patients born within 482 weeks of the eligibility threshold of 2 November 1936. The average age in this subset was 77 years, with 54.3% of participants being women. The likelihood of the Hz vaccine increased from 6.5% among non -eligible people to 30.2% among the eligible people, confirming that the rule of the date of the birthness effectively differentiated the vaccine exposure.
It is important that there were no differences in previous health conditions, recruitment of other preventive services or dementia risk factors across the entire eligibility threshold, supporting the validity of the physical experiment. An analysis of discontinuity regression has shown that the eligibility for HZ vaccination led to a statistically significant reduction in 1.8 percentage points in the likelihood of a new diagnosis of dementia over a period of 7.4 years (95%confidence interval: 0.4 to 3.3, p = .01). The protective effect was consistent with alternative monitoring orders, grace periods and model specifications.
Additional checks, including those limited to frequent primary care users and time models at an event, supported the main findings. No results were observed in other common diagnoses or preventive health behaviors, indicating that the result was specific to dementia. The comparative RD using an additional non -eligible group gave a similar size of 1.5 percentage points. Kaplan-meier plots and the cumulative impact curves further showed the delayed appearance of dementia in people who have chosen with a vaccine.
The study ruled out by confusing, confirming that no other interventions used the same rule of birth date eligibility and proving that the result was unique to the 1936 birth limit. Analyzes that shift the doorstep in the near years did not show a similar effect, validating it.
It is also important to note that dementia diagnoses are essentially subjective to the primary care data analyzed. For example, only 1.4% of patients over 65 years of age in Penss’s data was diagnosed with dementia, compared to about 8.4% in the Australian general population. This subject means that the magnitude of the absolute effect observed may not fully reflect the effect of Hz vaccination on the risk of dementia in the wider population.
These findings, when combined with similar research from Wales, provide consistent and urgent evidence that Hz vaccination can help prevent or delay dementia.
Conclusions
In summary, this study showed that people eligible for free Hz vaccination due to their date of birth were significantly lower chance of diagnosis of dementia over a 7.4 -year surveillance period. The use of a quasi -experimental design allowed the comparison between almost identical groups, minimizing the confusion and providing stronger causal conclusions than traditional observation studies. These findings emphasize the ability to vaccinate Hz to serve as low cost intervention to prevent dementia. However, further studies are required in additional populations, as well as mechanistic and clinical studies to investigate the biological paths, generality and the consequences of these promising results.
