Researchers in the US have found that small amounts of a hallmark Alzheimer’s protein, amyloid, may be present inside some brain cells in healthy younger adults. The study is published on Monday 2 March in the journal Brain.
In Alzheimer’s, a protein called amyloid changes shape, forming toxic fragments. These fragments of amyloid begin to accumulate in the brain, sticking together to form clumps around nerve cells. Previous research has shown this is one of the first changes in the brain seen in Alzheimer’s, and that amyloid build-up reaches a peak before symptoms such as memory loss become apparent.
Scientists at Northwestern University in Chicago compared brain tissue from people who had died at different ages – 13 people aged 20 to 66 without cognitive problems, 16 older people without dementia, and 21 older people with Alzheimer’s disease. They looked in particular at nerve cells called basal forebrain cholinergic neurons, which are important for memory. Research has suggested that these cells are the first to die in Alzheimer’s disease, and also die early as part of normal ageing.
Their results showed that small fragments of amyloid could be found inside cells in people of all ages, with larger clumps present in older people, and the largest clumps found in the brains of people with Alzheimer’s. The researchers suggest that the presence of the protein inside basal forebrain cholinergic neurons could explain why these memory cells are particularly vulnerable to damage in Alzheimer’s.
Dr Laura Phipps of Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
“Amyloid is present in all healthy brains, and though its normal function is not yet fully understood, in its usual form the protein does not cause damage. We know that the build-up of sticky forms of amyloid outside cells is a key event in Alzheimer’s disease, and this research suggests that it may also be important to study its role inside nerve cells. A better understanding of the protein’s behaviour and its effects on the brain could be vital for informing the development of new treatments. This small study helps add a piece of this puzzle, and could point to a possible new avenue for research to understand how amyloid affects the brain throughout life.
“With half a million people living with Alzheimer’s in the UK and that number on the increase, we urgently need new treatments to stop the disease in its tracks. A greater understanding of the early stages of Alzheimer’s could provide new clues to help fight the disease, which is why investment in research is crucial.”