Alzheimer’s disease progresses in two different stages, scientists have shown for the first time.
The first stage involves subtle changes in an overlooked part of the brain and occurs decades before symptoms ever appear.
The second phase is rapid and involves massive cell death and the build-up of bundles of proteins that affect memory and speech.
Scientists say there is a crucial window between these two stages to catch and stop the disease before it really takes hold.
Dr. Richard Hodes, director of the NIH Institute of Aging, which funded the study, said: ‘The results fundamentally change scientists’ understanding of how Alzheimer’s disease damages the brain and will guide the development of new treatments for this devastating condition.’
A doctor from the Allen Institute has shown that the folds in the brain of a person with advanced dementia are further apart than in a healthy brain, which is evidence of tissue loss.
In 2022, Chris Hemsworth discovered that he was genetically predisposed to Alzheimer’s disease and made this information public. The discovery hasn’t stopped the action star from working
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He added: ‘The ability to detect these early changes means that for the first time we can see what happens to a person’s brain during the earliest periods of the disease.’
About 7 million Americans are currently living with Alzheimer’s disease and these cases are expected to increase to 13 million by 2050, partly due to the aging of the population. the Alzheimer’s Association.
About one in five women develops the disease, and one in ten men. In 2022, Marvel actor Chris Hemsworth, 40, discovered he was likely to develop the disease after undergoing genetic testing.
He has become a public figure in the fight against dementia. This includes sharing details about his health and wellness routines and encouraging others to attend regular doctor visits.
Despite how common the disease is, there is a lot that science doesn’t understand what causes dementia and how it progresses.
This new study posted by researchers at the University of Washington and the NIH’s Allen Institute for Brain Science, in journal Nature Neuroscienceadds a whole new theory to the field.
They studied more than 3.4 million individual cells taken from the brains of 84 deceased donors, from a part of the brain called the middle temporal gyrus.
This region is critical for both language and memory processing, and older research has suggested that it is one of the first to fail in dementia.
They compared the unhealthy cells with those from previous research among healthy individuals using a complex computer algorithm.
They discovered that there are two main stages in Alzheimer’s disease.
The first phase occurs quietly, with subtle changes in the cells that protect the neurons, increased inflammation and minor cell loss.
This happens over a long period of time and does not affect the person’s memory.
Dr. Igor Carmargo Fontana, director of scientific conference programming of the Alzheimer’s Association told Fox News these changes can take decades before anyone is noticeably affected.
The second phase is fast and brutal and is characterized by the rapid formation of large protein plaques that crowd and suffocate healthy brain tissue.
This coincides with the period when a person actually begins to lose memory and cognition. It is unclear what drives these changes.
In normal aging, the brain slowly loses some volume over time, but this is not specific to certain cell types, or changes rapidly in rate, as in dementia. In addition, the protein plaques that occur in dementia are not as common in normal aging.
The researchers studied cells from the temporal gyrus, a region located near the base of the brain and crucial for language and memory
Researchers were surprised to find that a cell type important for interrupting signaling in the brain was among the first to die. Other cell types, such as the cells that insulate and nourish nerves, were also affected early on
The two-stage model contrasts with what researchers previously thought, which is that the disease takes over the brain in a multi-step process.
Study author and neuropathologist Mariano Gabitto said: ‘You could say that we have created a pathology clock that tells not only what changes occur in this cortical area, but also when.’
The researchers wrote that focusing on these subtle changes in the early stages could help them develop treatments for the disease before it starts to affect memory.
They were particularly surprised to find that one cell type seemed to succumb first: the inhibitory neurons that express somatostatin.
These cells are important in controlling the way the brain fires, and are crucial for things like attention.
In the first phase, the researchers discovered that brain inflammation disables these cells.
Future studies could investigate how these cells and others can be protected from dying so that the memory-robbing disease can be stopped before it reaches the second stage, says Dr. John Ngai, director of the BRAIN Institute.
Dr. Ngai added: ‘the new knowledge provided by this study could help scientists and drug developers around the world develop diagnostics and treatments targeting specific stages of Alzheimer’s disease and other forms of dementia.’