Scientists have found a possible reason why brain cells become damaged in Parkinson’s disease.
The discovery points to a failure in the cells’ natural waste-removal system, which normally clears away damaged parts before they can cause trouble.
Parkinson’s disease is a long-term brain condition that affects millions of people worldwide, especially older adults. It is best known for symptoms such as shaking, muscle stiffness, slow movement and problems with balance.
These symptoms develop as certain nerve cells in the brain are gradually lost. Many of the affected cells make dopamine, a chemical that helps the brain control smooth and coordinated movement.
Scientists have spent decades trying to understand why these cells die. One important area of research involves mitochondria, tiny structures inside cells that produce much of the energy the cells need to survive and work properly.
Mitochondria can become damaged as cells age or face stress. Healthy cells normally identify worn-out mitochondria and remove them through a recycling process, helping to prevent harmful material from building up.
A research team at the University of Copenhagen found evidence that this cleaning process may be disrupted in Parkinson’s disease. When damaged mitochondria are not removed, they can pile up inside brain cells and interfere with normal energy production.
This is especially serious for brain cells because they need a large and steady supply of energy. Over time, the buildup of damaged cell parts may weaken the cells and make them more likely to die.
The researchers also found an unexpected link with the immune system. Some genes that normally help the body respond to viruses also appear to be involved in maintaining healthy mitochondria and controlling the cell’s cleanup process.
One of the genes studied has previously been linked to the way some people respond to COVID-19. This does not mean that COVID-19 causes Parkinson’s disease, but it adds to growing evidence that the immune system and brain health can influence each other in complex ways.
To investigate the problem, the scientists studied cells from people with Parkinson’s disease and compared them with cells from people of a similar age who did not have the condition. They found unusually high amounts of a substance called PIAS2 in the Parkinson’s cells.
PIAS2 appears to interfere with the system that removes damaged mitochondria. When that system is blocked, unhealthy mitochondria remain inside the cells and may contribute to the production and buildup of other harmful substances.
This could create a damaging cycle. The cells lose some of their ability to produce energy, harmful material accumulates, and the environment inside the brain becomes less healthy for nerve cells.
Parkinson’s disease can affect more than movement. As the condition progresses, some people also develop sleep problems, mood changes, difficulties with thinking and memory, and in some cases dementia.
The findings may eventually help scientists develop treatments that target the disease more directly. Current Parkinson’s medicines can improve symptoms, including movement problems, but they do not stop the underlying loss of brain cells.
If researchers can find a safe way to reduce the harmful effects of PIAS2 or restore the cells’ cleanup system, it may be possible to protect brain cells for longer. However, the work is still at an early stage, and more research is needed before this approach can be tested as a treatment for patients.
The study was led by Professor Shohreh Issazadeh-Navikas and researchers at the University of Copenhagen. The research was published in the scientific journal Molecular Psychiatry.
The discovery gives scientists another clue about how aging, immunity and the brain’s energy system may work together in Parkinson’s disease. Understanding these connections could eventually lead to treatments that do more than ease symptoms and instead slow the damage occurring inside the brain.
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