Researchers were able to discover a subgroup in the National Brain Bank of the Netherlands that exhibited Alzheimer's disease symptoms but never showed such symptoms while the people were still alive.
This came after they studied over 2,000 brains from the Brain Bank of the Netherlands.
Asymptomatic Alzheimer's Disease With Signs Observed in the Brain
Alzheimer's disease typically leads to a decline in thinking, memory, organizing, and learning skills as time passes. It is considered the most common dementia cause, and it typically affects individuals who are over 65 years of age.
The study, entitled "Gene-expression profiling of individuals resilient to Alzheimer's disease reveals higher expression of genes related to metallothionein and mitochondrial processes and no changes in the unfolded protein response," discovered that the subgroup had clear Alzheimer's disease indications within the tissue of the brains. However, these individuals did not exhibit symptoms when they were still alive.
The researchers were only able to identify 12 individuals from the brain tissue available and with the necessary clinical data. Nevertheless, it sparked questions regarding the nature of the condition and what contributes to a person's resilience towards it.
When Alzheimer's disease is there without symptoms, it is called "resilience."
In the group that was resilient, researchers were able to observe that a brain cell type known as astrocytes, which they labeled as garbage collectors with protective brian roles, appeared to produce more of the metallothionein antioxidant.
When they interact with the brain's microglia, astrocytes could boost inflammation. However, the pathways associated with Alzheimer's appeared less active compared to the group that was resilient.
The researchers were also able to discover that a brain cell response meant to remove toxic proteins that were misfolded was quite normal in the group that was resilient.
Such an unfolded protein response typically gets affected among patients with Alzheimer's. There were also signs that the brain cells of resilient individuals had more mitochondria compared to the cells of other patients with Alzheimer's. This implied that the resilient group would have had stronger energy production.
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Resilience and Cognitive Reserve
David Merrill, MD, PhD, a geriatric psychiatrist and the director of the Pacific Brain Health Center of the Pacific Neuroscience Institute in Providence Saint John's Health Center, who was not involved in the study, said that lifestyle and genetics might play a role in this kind of resilience.
Merrill explains that cognitive reserve, which is the resilience of the brain towards damage, has a significant role to play. Moreover, lifestyle, genetic, and environmental factors may all modulate the severity and onsets of symptoms despite the pathology that underlies them.
Yuko Hara, PhD, the director of the Alzheimer's Drug Discovery Foundation's (ADDF) Aging and Alzheimer's Prevention, who did not participate in the study, said that there could have been a 20 to 30-year lag between the brain's first amyloid deposit signs and symptom onset.
Hara also explained some ways for people to build their cognitive reserve up in time. The experiences and knowledge that people gain across their life could help them to cope better with pathologies, such as beta-amyloid, and retain better cognitive function for longer periods.
Some steps that could help boost cognitive reserve include taking a class to learn something new, learning a new language, reading books, learning how to play a musical instrument, and challenging or stimulating the brain in various ways.
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