Researchers gain more evidence that Parkinson’s disease starts at a person’s stomach, where it eventually climbs its way up the human body’s brain tissues causing detrimental effects.
It is long established the Parkinson’s disease is closely related to the death of brain tissues, specifically the nerve cells in the midbrain. The condition is a slow and agonizing death sentence, where it kills off nerve cells causing the person infected to gradually lose control over their motor skills such as balancing, walking, holding, eating, and even talking.
Over time, the disease becomes increasingly severe that patients end up bedridden and often die because the autonomic nervous system is no longer functioning correctly.
Research explains that the disease is caused by a naturally-forming protein called alpha-synuclein, which is usually found in the brain in the endings of nerve cells. However, these proteins can sometimes mutate and fold, causing damage to the nerve cells of the substantia nigra pars compacta (SNc)— a core area of the midbrain. Among other things, SNc is responsible for the production of the hormone dopamine, which performs many vital tasks in the body, such as controlling blood flow.
The dead nerve tissues are then seen as a pool of dead brain matter called Lewy bodies. These pools represent areas of the brain that could affect a person, such as motor skills or how a person regulates their emotions.
In a new study by Johns Hopkins University School of Medicine, they were able to collect significant evidence that the disease is connected to the stomach. The study was published in the journal Neuron.
To prove their hypothesis, they used mice as test subjects and injected their stomach linings or nerves between the stomach mucosa with high concentrations of the mutated and folded proteins.
Researchers believed that the mutated nerves would climb its way to the brain through the vagus nerve—connects the brain and the gut—like a ladder.
In their findings, several months after the injection, they discovered that the mutated proteins were found in different parts of the mice’s midbrain and spreading as expected with early Parkinson’s disease in humans.
To prove the theory, researchers also injected a different set of mice but with their vagus nerve severed, and there was also a control group without an injection.
In the experiment, they put the three sets of mice in controlled situations to measure motor skills, anxiety, and overall behavior. Specifically, the three sets of mice were made to build their nests and explore new environments.
They discovered that both the control group and the group with severed vagus nerves showed normal mice behavior as opposed to the group with mutated proteins injected in their stomach linings. Notably, the latter showed significant anomalies in terms of motor and anxiety behaviors—hallmarks of Parkinson’s disease.
“These findings provide further proof of the gut’s role in Parkinson’s disease, and give us a model to study the disease’s progression from the start,” says Ted Dawson, M.D., Ph.D., director of the Johns Hopkins Institute for Cell Engineering and professor of neurology at the Johns Hopkins University School of Medicine.
Although nothing definitive has been established for Parkinson’s disease, the team is encouraged to find therapies and other possible measures to prevent the disease from progressing. “We have what we think is a really accurate [animal] model that can be used to work out mechanisms – but also to test therapies,” said Dawson.
Worldwide, more than 10 million people are living with Parkinson’s. Meanwhile, in the US, nearly one million people will be living with the disease by 2020, which is more than the combined number of people diagnosed with multiple sclerosis, muscular dystrophy and Lou Gehrig’s disease (or Amyotrophic Lateral Sclerosis).
Annually, approximately 60,000 Americans are diagnosed with Parkinson’s every year. The Parkinson’s Foundation estimates that the “combined direct and indirect cost of the disease, including treatment, social security payments and lost income, is estimated to be nearly $52 billion per year in the United States alone.”
Furthermore, they indicated that men are 1.5 times more likely to be diagnosed with the disease before the age of 50.
Dr. Beckie Port, research manager at the charity Parkinson’s UK, said the latest research builds on previous studies.“This study adds support to a growing base of evidence [implying] that changes in the gut play a key role in the initiation of Parkinson’s, although it is not believed to be the only place where the condition may start,” she told The Guardian.
“By identifying and halting these changes before they reach the brain, we may be able to prevent the majority of Parkinson’s symptoms ever appearing and improve the lives of people who will be affected.”