Amyloid and tau proteins have long been linked to the development of Alzheimer’s, yet frustratingly, their presence can’t reliably predict the onset of the disease.
The challenge for scientists has been to find a more reliable protein that can act as an early indicator, years before symptoms first appear. One group of scientists believe they may have found it.
Our bodies contain tens of thousands of proteins, some of which must inevitably be involved in kickstarting the process that leads to Alzheimer’s. It makes sense therefore to look further afield than amyloid and tau proteins, particularly since techniques for measuring many proteins from a small blood sample have advanced a great deal in recent years.
So a large group of scientists led by Johns Hopkins Bloomberg School of Public Health did just that, hoping a more comprehensive analysis of blood proteins would bear fruit.
38 Proteins Tied to Alzheimer’s
To begin with, they looked at blood samples drawn between 2011 and 2013 from a large sample of 4,110 people in late middle age who took part in the Atherosclerosis Risk in Communities (ARIC), a study that’s been running in the U.S. since 1985.
Using a recently developed technology called SomaScan to record 4,877 blood plasma proteins, they compared those who remained free of Alzheimer’s disease with 428 who developed the disease within five years following the blood draw.
The scientists found 38 proteins at abnormal levels in those who developed Alzheimer’s disease.
Predicts Two Decades in Advance
In the next stage of research the team turned to another 11,000 samples drawn in the 1990s from younger ARIC participants. Then, they followed up almost two decades later during mid-life for these participants.
This time researchers found abnormal levels of 16 proteins from the previously identified 38 proteins that continued to be linked to Alzheimer’s.
Next, they sought to verify their findings in a different patient population by looking at SomaScan samples from an Icelandic study where blood samples were taken between 2002 and 2006.
After a ten year follow up, they found six of the 16 proteins were associated with the development of Alzheimer’s. Having whittled the list down, the researchers now wanted to see if they could narrow their search even further.
One Protein Stands Out
During an additional analysis they compared these proteins with data from previous studies of genetic links to Alzheimer’s. Doing so pointed strongly to one particular protein called SVEP1 as an actual trigger or driver of Alzheimer’s disease.
The researchers wrote, “SVEP1, an immunologically relevant cellular adhesion protein, was found to be part of larger dementia-associated protein networks, and circulating levels were associated with atrophy in brain regions vulnerable to Alzheimer’s pathology.”
Senior author of the study, Josef Coresh, commented saying, “This is the most comprehensive analysis of its kind to date, and it sheds light on multiple biological pathways that are connected to Alzheimer’s.
“Some of these proteins we uncovered are just indicators that disease might occur, but a subset may be causally relevant, which is exciting because it raises the possibility of targeting these proteins with future treatments.”
The Johns Hopkins group plans to continue using techniques like SomaScan to identify potential Alzheimer’s-triggering pathways and hopes their findings will lead to new treatment options. I’ll keep you posted on their research.