Alzheimer’s occurs in two distinct stages, scientists have shown for the first time.
The first stage involves subtle changes in an overlooked area of the brain and occurs decades before symptoms ever occur.
The second stage is rapid and includes massive cell death and the build up of bundles of proteins that affect memory and speech.
Scientists say a crucial window exists between these two stages for them to catch and halt the disease before it really takes hold.
Dr Richard Hodes, the director of the NIH Institute of Aging, which funded the study, said: ‘The results fundamentally alter scientists’ understanding of how Alzheimer’s harms the brain and will guide the development of new treatments for this devastating disorder.’
A doctor from the Allen Institute demonstrated that the folds in the brain of a person with advanced dementia are more spaced out then they would be in a healthy brain, which is evidence of tissue loss
In 2022, Chris Hemsworth found out he was genetically predisposed to Alzheimer’s, and went public with this information. 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 is happening to a person’s brain during the earliest periods of the disease’.
Roughly 7million Americans currently living with Alzheimer’s and those cases are expected to grow to 13million by 2050, in part due to an aging populous, according to the Alzheimer’s Association.
Roughly one in five women get the disease, and one in ten men. In 2022, Marvel actor Chris Hemsworth, 40, found out he was likely to develop the disease, after going through genetic testing.
He’s 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 doctors visits.
Despite how common the disease is, there’s a lot that science doesn’t understand about what causes the dementia, and how it progresses.
This new study posted by researchers from the University of Washington and the NIH’s Allen Institute for Brain Science, in the journal Nature Neuroscience, adds a whole new theory to the field.
They studied more than 3.4million individual cells coming from the brains of 84 deceased donors, from a part of the brain called the middle temporal gyrus.
This region is crucial in both language and memory processing, and older research has suggested its one of the first to give out in dementia.
They compared the unhealthy cells to those in previous research of healthy individuals using a complex computer algorithm.
They found that there are two major phases of Alzheimer’s disease.
The first phase occurs quietly, with subtle changes to the cells that protect neurons, increased inflammation and minor cell loss.
This happens over a long period of time, and doesn’t affect the person’s memory.
Dr Igor Carmargo Fontana, the Alzheimer’s Association director of scientific conference programming told Fox News these changes could begin decades before someone is noticeably affected.
The second stage is rapid and brutal – characterized by the quick formation of big protein plaques that crowd healthy brain tissue, smothering it.
This coincides with the period when someone actually begins losing memory and cognition. It’s unclear what drives these changes.
In normal aging, the brain slowly loses some volume over time, but it isn’t specific to certain cell types, or rapidly changing in pace, as it is in dementia. In addition, the protein plaques seen in dementia don’t appear as widely in normal aging.
The researchers studied cells from the temporal gyrus, a region which sits near the base of the brain, and is crucial in language and memory
Researchers were surprised to find that a cell type that is important for putting the breaks on signaling in the brain were some of the first to die off. Other cell types, like those that insulate and feed the nerves, were also affected early on
The two phase model stands in contrast to what researchers previously thought – which is that the disease takes over the brain in a many stepped process.
Study author and neuropathologist Mariano Gabitto said: ‘You could say that we created a pathology clock that tells not only what changes are happening in this cortical region, but when.’
The researchers wrote that focusing on these subtle changes in the first stage could help them develop treatments for the disease before it begins affecting memory.
In particular they, were surprised to find that one cell type seemed to give out first – called the somatostatin-expressing inhibitory neurons.
These cells are important in controlling the way the brain fires, and are crucial for things like attention.
In the first phase, the researchers found that brain inflammation knocks these cells out.
Future studies can investigate how to protect these cells and others from dying off in order to halt the memory-robbing disease before it gets to the second stage, Dr John Ngai, the director of the BRAIN Institute, said.
Dr Ngai added: ‘the new knowledge provided by this study may help scientists and drug developers around the world develop diagnostics and treatments targeted to specific stages of Alzheimer’s and other dementias.’
