- Researchers say hospital-treated infections early in life may increase the risk of Alzheimer’s disease and Parkinson’s disease.
- They add that these infections don’t appear to affect the risk of eventually developing amyotrophic lateral sclerosis (ALS).
- Experts say serious infections may cause the body to fight off these invaders instead of performing more common duties to prevent the progression of disease.
Infections treated in the hospital in early adulthood and mid-life may increase the risk of developing Alzheimer’s disease and Parkinson’s disease later in life.
That’s according to a study conducted by Jiangwei Sun and colleagues at Karolinska Institute in Sweden and published today in the journal PLOS Medicine.
In the study, researchers report that people with hospital-treated infections could have a higher risk of Alzheimer’s disease and Parkinson’s disease. The risk for amyotrophic lateral sclerosis (ALS) did not seem to be affected.
The idea that infections can affect the development of Alzheimer’s disease and Parkinson’s disease has been around for several years.
A studyTrusted Source published in 2018 suggested that systemic infections can accelerate cognitive decline in people with Alzheimer’s disease.
An articleTrusted Source published in the journal Nature in 2020 outlined some of the research in the past decade that supports the theory.
A study published in 2022 discussed the presence of Alzheimer’s disease-like pathology in aged cattle that was potentially related to infection.
Details from the new study
In the recent study, researchers looked at data on people diagnosed with Alzheimer’s disease, Parkinson’s disease, and ALS between 1970 and 2016 in Sweden.
The data included 291,941 records for Alzheimer’s disease, 103,919 records for Parkinson’s disease, and 10,161 records for ALS. They compared these to hospital-treated infections five or more years before the study.
They found that people who had hospital-treated infection had a 16% percent higher risk of Alzheimer’s disease and a 4% higher risk of Parkinson’s disease.
People who had multiple hospital-treated infections before the age of 40 had a higher risk – more than double the risk for Alzheimer’s disease and more than 40% higher for Parkinson’s disease.
The scientists did not observe any association between the infections and ALS, regardless of the age of diagnosis.
“Our study did not support an association of hospital-treated infections with risk of ALS,” said Jiangwei Sun, the lead author of the study and a postdoctoral researcher at Karolinska University. “However, this does not rule out mild infections not attended by specialist care. Previous studies have shown that infections might contribute to pathological processes of ALS. Virus-like symptom sequences have been found in the central nervous system of ALS patients.”
How infections can cause disease progression
The researchers indicated that the findings could suggest the infections triggered or amplified a pre-existing disease process leading to neurodegenerative disease.
Dr. Melita Petrossian, a neurologist and director of the Movement Disorders Center at Providence Saint John’s Health Center in California, explained the connection.
“An easy way to conceptualize the role of systemic inflammation in the risk of neurodegenerative disease is that the body works simultaneously over decades to fight infection and inflammation, and to clear out toxic or metabolic build-up that contributes to neurodegenerative disease,” she told Healthline. “The more focus the body has on fighting infection or inflammation, the less it can focus on clearing out metabolic building. It’s like an army being overwhelmed on multiple fronts.”
Another expert has a slightly different interpretation.
“I am not convinced that infections cause the observed results concerning [Alzheimer’s disease] and [Parkinson’s disease]. But, there are examples of infections triggering non-infectious syndromes, for example, rheumatic fever, streptococcal glomerulonephritis, Lyme disease, and Reiter’s syndrome,” said Dr. Charles Bailey, medical director for infection prevention at Providence St. Joseph Hospital and Providence Mission Hospital in California.
“The theory is that the acute infection triggers an extended immune response that subsequently ‘attacks’ non-infected tissues, such as heart valves, kidneys, skin/mucus membranes, and joints. A similar situation with neurologic tissue as the target could occur with [Alzheimer’s disease] or [Parkinson’s disease],” he told Healthline.
What are neurodegenerative diseases?
Neurodegenerative diseases are a group of progressive conditions that affect nervous system connections that influence mobility, coordination, strength, sensation, and cognition, according to UT Southwestern Medical Center.
The conditions include:
- Alzheimer’s disease
- Ataxia
- Huntington’s disease
- Parkinson’s disease
- Motor neuron disease
- Multiple system atrophy
- Progressive supranuclear palsy
Neurodegenerative diseases are caused when nerve cells stop working, lose function, or die, according to the Keck School of Medicine at USC.
Treatments can sometimes slow the progression. However, there are not any treatments to prevent, stop, or reverse the damage. Most treatments are symptomatic, meaning they treat symptoms, not the disease.
For example:
- Dopaminergic treatment can be used to treat Parkinson’s disease and other movement disorders.
- Anti-inflammatory drugs can treat neuronal infections.
- Antipsychotics can help reduce symptoms of dementia.
- Cholinesterase can help with cognitive issues.
Other therapies, such as physiotherapy, speech therapy, occupational therapy, and psychiatry, can be used to help maintain daily activities. Often, a combination of therapies is used to best cater to an individual’s needs.
The prognosis
Around 5 million people in the United States have Alzheimer’s disease and 1 million have Parkinson’s disease.
The risk of developing a neurodegenerative disease increases with age, and medical experts predict that in 30 years, more than 12 million people will have some neurodegenerative disease.
It is believed that a combination of genes and environment contribute to the risk of developing one of these diseases. Scientists worldwide are working to better understand these conditions and how to treat and prevent them.
In the meantime, there are ways to reduce your risk of needing to be hospitalized for infections.
“Try to find ways to prevent the infection by practicing good hygiene,” suggests Sri Banerjee, PhD, a faculty member at the College of Health Sciences & Public Policy at Walden University in Minnesota.
“Make sure to finish the entire course of prescribed antibiotics to ensure there is no antibiotic resistance, which is another reason you may need to be hospitalized, depending on where the infection is. Rely on oral and topical antibiotics to treat any infections early on before complications,” Banerjee told Healthline.
