Lewy body disease is a serious condition that slowly damages the brain.
It can affect memory, thinking, movement, sleep, mood, and a person’s ability to carry out everyday activities.
It is one of the most common causes of dementia, second only to Alzheimer’s disease. Lewy body disease is also closely connected with Parkinson’s disease and dementia with Lewy bodies, two conditions that can look different at first but share important changes in the brain.
The disease is named after Lewy bodies, which are abnormal clumps of protein that collect inside brain cells.
A major part of these clumps is a protein called alpha-synuclein, which normally exists in the brain but can change shape and begin sticking together.
As these abnormal proteins build up, they can disturb communication between brain cells and eventually damage them. If movement problems appear first, a person may initially be diagnosed with Parkinson’s disease, while early problems with thinking and memory may lead to a diagnosis of dementia with Lewy bodies.
Finding the disease early has been difficult because its symptoms can overlap with other brain conditions. In the past, confirming Lewy bodies with certainty often depended on examining brain tissue after a person died.
Researchers from Lund University in Sweden have now reported an important step toward detecting the disease much earlier. Their research, published in the journal Nature Medicine, showed that signs of Lewy body disease can be found in people who do not yet have clear memory or movement problems.
The scientists examined cerebrospinal fluid, the clear liquid that surrounds the brain and spinal cord. Because this fluid is in close contact with the brain, it can contain biological clues about changes happening in brain cells.
The study included more than 1,100 people who did not have obvious problems with thinking or movement when they were tested. Around 10% already showed evidence of abnormal alpha-synuclein linked to Lewy body disease.
This was important because these people appeared healthy at the beginning of the study. As researchers followed them over time, those with signs of Lewy body disease were more likely to develop problems with thinking and memory.
Some were later diagnosed with Parkinson’s disease or dementia with Lewy bodies. The findings suggest that harmful changes in the brain may begin years before symptoms become noticeable enough for a diagnosis.
The researchers also found an interesting connection with the sense of smell. People with early signs of Lewy body disease were more likely to have difficulty identifying smells, even when they had no other obvious symptoms.
Loss of smell is already known to occur early in some people who later develop Parkinson’s disease. The researchers suggested that smell testing could eventually help identify older adults who might benefit from more detailed testing.
Early detection could become especially important as scientists develop treatments designed to slow or stop the disease itself. Once large numbers of brain cells have been damaged, it may be much harder for a treatment to restore lost abilities.
A test that identifies the disease before major symptoms begin could therefore help researchers find the right people for clinical trials. In the future, it might also allow treatment to begin at a stage when the brain has suffered less damage.
The study revealed another important clue about how quickly the disease may progress. Some people with signs of Lewy body disease also had abnormal proteins associated with Alzheimer’s disease, and these people tended to decline more quickly.
This suggests that different brain diseases can occur at the same time. Knowing which proteins are present could eventually help doctors better predict how a person’s condition may develop and choose treatments more carefully.
The current test relies on cerebrospinal fluid, which usually requires a lumbar puncture to collect. Researchers hope that a blood test for Lewy body disease may eventually become possible, similar to the newer blood tests being developed and used for Alzheimer’s disease.
A simple blood test is still a future goal because signs of abnormal alpha-synuclein are much harder to detect in blood. Even so, the new findings show that Lewy body disease may be detectable long before it becomes obvious, opening the door to earlier diagnosis and, potentially, earlier treatment.
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