Possible blood test for Alzheimer’s disease

The New York Times reports on a study shortly to be published in Nature Medicine that has developed a blood test that can predict the development of Alzheimer’s disease with 90% accuracy.

One of the difficulties with Alzheimer’s disease, and indeed most forms of dementia, is that by the time the characteristic mental difficulties are noted, the disease has already been affecting the brain for some time.

It would be useful if these changes could be detected way before they started to affect memory, attention and so on, so the clinical team can intervene as soon as possible.

To this end, the researchers looked at the levels of various proteins in the blood of a number of older people who had ‘mild cognitive impairment‘ – detectable but relatively slight mental difficulties for their age.

Each participant was followed up so the team knew whether these initial cognitive difficulties developed into Alzheimer’s disease or not.

A statistical analysis looked at which of 120 proteins most distinguished the two groups and a group of 18 key proteins were identified which could be used to diagnose the groups with 90% accuracy.

Interestingly, the protein analysis suggested that Alzheimer’s may be linked to problems with inflammation, blood growth, neuroprotection, neural growth, waste cell removal and energy regulation.

The clinical diagnosis of Alzheimer’s disease is based on mental difficulties and possible brain scan evidence. However, it can’t be diagnosed for certain until the brain is examined after the person has died.

In this case, an additional important step was completed by examining some of the post-mortem brains to confirm the diagnosis and, reassuringly, the blood test retained its accuracy.

It seems that this test is only useful in picking up people who are already developing the disorder but don’t show any symptoms yet, so it can’t be used on young people to determine who will develop the disorder later in life.

Link to NYT article ‘Progress Cited in Alzheimer‚Äôs Diagnosis’.
Link to write-up from Nature News.
Link to abstract of scientific study.

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