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Repeat infections linked to increased risk of certain neurodegenerative diseases – Neuroscience News

Summary: Infections in early to midlife that require hospital care are associated with an increased risk of developing Alzheimer’s and Parkinson’s disease later in life, a new study has found.

Source: OLP

According to a new study published on September 15, infections treated with specialized hospital care in early and middle life are associated with an increased later risk of Alzheimer’s disease (AD) and Parkinson’s disease (PD), but no amyotrophic lateral sclerosis (ALS).e in the open access journal OLP Medicine by Jiangwei Sun of the Karolinska Institute, Sweden, and colleagues.

Experimental studies in animals have suggested that infection plays a role in the development of certain neurodegenerative diseases, but supporting evidence in humans is limited.

In the new study, researchers used data on people diagnosed with AD, PD or ALS from 1970 to 2016 in Sweden, along with five case-matched controls, all identified from the Swedish National Patient Registry. The analysis included 291,941 AD cases, 103,919 PD cases and 10,161 ALS cases.

Researchers assess the infection treated in the hospital and the risk of neurodegenerative diseases. 1 credit

Infection treated in hospital 5 or more years before diagnosis was associated with a 16% increased risk of AD (95% CI: 1.15-1.18, P < 0.001) and an increased risk of 4 % PM (95% CI: 1.02-1.06, P < 0.001), with similar risks observed for bacterial, viral and other infections and for different sites of infection.

The highest risk of disease was observed in people with multiple infections hospitalized before the age of 40 years, with more than twice the risk of AD (OR = 2.62, 95% CI: 2.52- 2.72, P < 0.001) and over 40 years % increased risk of PD (OR = 1.41, 95% CI: 1.29-1.53, 3 44 P < 0.001). No association was observed for ALS, regardless of age at diagnosis.

“These findings suggest that infectious events may be a trigger or amplifier of a pre-existing disease process, leading to the clinical onset of neurodegenerative disease at a relatively early age,” the authors state, while emphasizing that ” due to the observational nature of the study, these results do not formally prove a causal relationship.

Sun adds, “Infections treated in hospital, particularly in early and midlife, were associated with an increased risk of Alzheimer’s disease (AD) and Parkinson’s disease (PD), primarily among cases AD and PD diagnosed before age 60.

Funding: This study was supported by the Swedish Research Council (Grant Nos: 2019-01088 (FF), 340-2013-5867 (FF) and 2017-02175 (KW)), the Joint Program on Neurodegenerative Diseases (JPND , grant number: 2021-00696 (FF)), and the Chinese Scholarship Council (JS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

About this neurodegeneration research news

Author: Claire Turner
Source: OLP
Contact: Claire Turner – PLOS
Image: Image is credited to Jiangwei Sun

Original research: Free access.
“Hospital-treated infections in early and mid-life and the risk of Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis: a nationwide nested case-control study in Sweden” by Jiangwei Sun and para. OLP Medicine


Summary

Infections Treated in Hospital in Early and Midlife and the Risk of Alzheimer’s Disease, Parkinson’s Disease, and Amyotrophic Lateral Sclerosis: A Nationwide Nested Case-Control Study in Sweden

See also

This shows the outline of a woman and a brain

Background

Experimental observations have suggested a role for infection in the etiology of neurodegenerative diseases. In human studies, however, it is difficult to determine whether infection is a risk factor or rather a comorbidity or secondary event of a neurodegenerative disease. To this end, we examined the risk of 3 most common neurodegenerative diseases in relation to previous episodes of inpatient or outpatient infections.

Methods and results

We performed a nested case-control study based on several national registers in Sweden. The cases were people newly diagnosed with Alzheimer’s disease (AD), Parkinson’s disease (PD) or amyotrophic lateral sclerosis (ALS) between 1970 and 2016 in Sweden, identified from the national patient registry. For each case, 5 controls individually matched to the case on gender and year of birth were randomly selected from the general population.

Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) with adjustment for potential confounders, including sex, year of birth, place of residence, level of education, family history of neurodegenerative disease and Charlson’s comorbidity index. Infections occurring within 5 years prior to diagnosis of neurodegenerative disease were excluded to reduce the influence of surveillance bias and reverse causation.

The analysis included 291,941 cases of AD (median age at diagnosis: 76.2 years; male: 46.6%), 103,919 cases of PD (74.3; 55.1%) and 10,161 cases of ALS (69.3; 56.8%). Infection treated in hospital 5 or more years ago was associated with an increased risk of AD (OR = 1.16, 95% CI: 1.15 to 1.18, P < 0.001) and PD (OR = 1.04, 95% CI: 1.02 to 1.06, P < 0.001). Similar results were observed for bacterial, viral and other infections and among different sites of infection, including gastrointestinal and genitourinary infections. Multiple infections before age 40 carried the greatest risk of AD (OR = 2.62, 95% CI: 2.52 to 2.72, P < 0.001) and PD (OR = 1.41, 95% CI: 1.29 to 1.53, P < 0.001).

The associations were mainly due to AD and PD diagnosed before age 60 (OR = 1.93, 95% CI: 1.89 to 1.98 for AD, P <0.001; OR = 1.29, 95% CI: 1.22 to 1.36 for PD, P < 0.001), while no association was found for people diagnosed at age 60 or older (OR = 1.00, 95% CI: 0.98 to 1.01 for AD, P = 0.508; OR = 1.01, 95% CI: 0.99 to 1.03 for PD, P = 0.382). No association was observed for ALS (OR = 0.97, 95% CI: 0.92 to 1.03, P = 0.384), regardless of age at diagnosis.

The exclusion of infections occurring in the 10 years preceding the diagnosis of neurodegenerative disease confirmed these results. Limitations of the study include potential misclassification of infections treated in hospital and neurodegenerative diseases due to incomplete coverage of the national patient registry, as well as residual confounding due to unmeasured risk or protective factors. for neurodegenerative diseases.

conclusion

Infections treated in hospital, particularly in early and mid-life, were associated with an increased risk of AD and PD, primarily among AD and PD cases diagnosed before age 60. These results suggest that infectious events may be a trigger or amplifier of a pre-existing disease process, leading to the clinical onset of neurodegenerative disease at a relatively early age. However, due to the observational nature of the study, these results do not formally prove a causal link.

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