Herpes virus infection linked to higher Alzheimer’s risk, study shows antiherpetic drugs may help

New research with American insurance data shows that people with HSV-1 have to deal with a greater chance of Alzheimer’s disease and suggests that antiviral medicines can help reduce that risk.

Study: Association between Herpes Simplex Virus Type 1 and the risk of Alzheimer’s disease: a retrospective case -control examination. Image Credit: Kateryna Kon / Shutterstock

Large-scale American Real-World Data (RWD) also offer evidence for a connection between Herpes Simplex Virus Type 1 (HSV-1) infection and the development of Alzheimer’s disease (AD) and points to the potential of the use of anti-therapy therapies that may be protective against AD and related dementia.

A recent BMJ Open Study from the United States investigated the association between HSV-1 and AD using RWD.

Alzheimer’s disease and herpes viruses

Ad is a chronic and progressive neurodegenerative disease that influences the thinking, reasoning and memory of an individual. Almost 60 % -80 % of people with AD develop dementia, which causes long-term care tax. At present, around 35.6 million people have been diagnosed with dementia worldwide and the rapid increase is attributed to an aging population. To combat the rising incidence of AD worldwide, there is an urgent need for effective interventions.

Persons with AD and related dementia develop a characteristic toxic protein gegate, with τ neurofibrillary tangles and central nervous system amyloid-β (Aβ) plaques that are pathological characteristics. An earlier study revealed the role of exogenous pathogens, in particular HSV-1, in the development of AD.

HSV-1 is a common viral infection that mainly occurs in the world’s world’s population between 0 and 49 years old. Most children who suffer this infection can remain asymptomatic. HSV-1 establishes latency in the trigeminal ganglia and shows periodic symptomatic reactivations, causing ocular disorders, oral ulcers and rarely meningo and falitis.

A mouse model investigation indicated that HSV-1 infection leads to AP deposition and other AD-related changes. In addition, experimental reactivation of HSV-1 infection changes in the pathological characteristics in a dose-response way. Various Real-World studies have shown that patients with the HSV-1 diagnosis and other related neurotrope viruses run a higher risk of developing dementia. Interestingly, studies conducted in Taiwan, Sweden and France showed protective effects of anti -therpetics against dementia.

Scientists have indicated that a large-scale study based on data from practice is indicated to validate the role of HSV-1 in AD development and the therapeutic effects of anti-therpetics against dementia.

About the study

The current retrospective Case-Control Study used in the US-based National Real-World data to demonstrate the association between HSV-1 and AD and AD-related dementia (ADRD), including Pick’s disease, Lewy Bodies, Frontotemporal dementia, vascular dementia.

Alle relevante gegevens met betrekking tot intramurale patiënten en poliklinische patiënten en recepten van toegediende medicijnen werden verkregen van IQVIA Pharmetrics Plus, de grootste commerciële claimsdatabase in de VS, bestaande uit meer dan 215 miljoen kandidaten sinds 2006. Omdat de studie afhankelijk is van administratieve claimsgegevens, onderschat het waarschijnlijk de werkelijke prevalentie van HSV-1, die vaak is geassisteerd of mocht niet worden gedreven of mogen not being driven. This means that the share of HSV-1 diagnoses recorded in this study is much lower than the actual prevalence in the general population, which is estimated worldwide at about two-thirds for people younger than 50 years old. Moreover, individuals older than 65 years are under -represented in this dataset.

Cases with AD or ADRD were linked to those without a history of neurological disorders (control) in a 1: 1 ratio about gender, age, region, database input and intramural and outpatient health care numbers. Two sets of matching and analyzes were performed. The index date for cases was the date on which patients were diagnosed with AD/ADRD for the first time between January 1, 2006 and June 30, 2021. For the matched checks, all candidates had to be 50 years or older on the index date. Persons with the HSV-1 diagnosis and other herpes viruses, such as HSV-2 and Cytomegalovirus (CMV), before the index date were registered.

Study findings

The current study identified 395,654 patients with AD, of whom 344,628 met the criteria of eligible. These candidates were linked to service elements. Most advertising group were women, with an average age of 73 years. Ad -patients belong to a large, evenly distributed geographical area.

Most patients with AD had more comorbidities and shorter follow-up times compared to the individuals in the control group. The current study noted that 1,507 (0.44%) patients with AD also had a history of HSV-1 diagnosis compared to 823 (0.24%) control persons.

Conditional logistics regression analysis revealed that HSV-1 diagnosis was associated with AD with an adapted Odds Ratio (OR) of 1.80. A stratified analysis showed that this association in older age groups was increasingly prominent. Similar observations are also documented in the ADRD research population. This study mainly found a connection between HSV-2 and VZV with AD, similar to HSV-1, while no significant difference was observed for CMV.

A subset analysis showed that 40% of 2,330 patients with a history of HSV-1 who received anti -herpetic drugs were a lower relative risk on the development of AD (adapted HR 0.83, 95% BI 0.74 to 0.92) compared to those who did not use anti-herpetics. It is important to note that this Hazard ratio reflects a relative risk reduction within the group of people with the HSV-1 diagnosis, rather than in the general population. However, this observed association does not state that anti -herpetic medication occurs Alzheimer’s disease; Further studies are needed to determine whether there is a causal relationship.

Conclusion

The current study also provides evidence for a link between symptomatic HSV-1 infection and AD using large-scale Real-World data. The most important thing is that it emphasizes that anti -herpetic therapies were associated with a reduced risk of AD in people diagnosed with HSV-1 diagnosis. However, this study can only establish an association, no causal connection, and various limitations, including under-diagnosis of HSV-1 and Alzheimer’s disease, potential misclassification and under-representation of older adults must be noted. The findings also suggest that the neurodegenerative impact of HSV-1 becomes clearer with the progressive age and cumulative exposure. In the future, more research is required to clarify or oppression of neurotrope viruses can change the natural history of AD and ADRD.