ALZHEIMER’S disease has no cure. There are, however, five drugs – known and approved – that can slow down the development of its symptoms. The earlier such drugs are administered, the better. Unfortunately, the disease is usually first noticed when people complain to their doctors of memory problems. That is normally too late for the drugs to do much good. A simple and reliable test for Alzheimer’s that can be administered to everybody over the age of about 65, before memory-loss sets in, would therefore be useful.
Theo Luider, of the Erasmus University Medical Centre in Rotterdam, and his colleagues think they have found one – but it works only in women. They made their discovery, just reported in the Journal of Proteome Research, by tapping into a long-term, continuing study that started in 1995 with 1,077 non-demented and otherwise healthy people aged between 60 and 90. At the beginning of the project, and subsequently during the periods 1997-99
and 2002-04, participants were brought in for a battery of neurological and cognitive investigations, physical examinations, brain imaging and blood tests.
During the first ten years of the study, 43 of the volunteers developed Alzheimer’s disease. When Dr Luider compared blood samples from these people with samples from 43 of their fellow volunteers, matched for sex and age, who had remained Alzheimer’s-free, he found something startling. Levels of a substance called pregnancy zone protein had been unusually high, even before their symptoms appeared, in some of those who went on to develop Alzheimer’s disease.
Those “some”, it turned out, were all women. On average, levels of pregnancy zone protein in those women who went on to develop Alzheimer’s were almost 60% higher than those of women who did not. In men, levels of the protein were the same for both.
The reason for this curious result seems to be that the brain plaques associated with Alzheimer’s disease are themselves turning out pregnancy zone protein. Certainly, when Dr Luider applied a chemical stain specific to that protein to the plaques of dead Alzheimer’s patients he found the protein present in them.
Confusingly, though, it was there in the plaques of both sexes. Presumably, female cells (and therefore the plaques of female brains) make more of it than male cells do. But that remains to be proved. Whatever the reason, however, this result means that women, at least, may soon be able to tell whether and when they are at risk of Alzheimer’s – and thus do something about it before they start losing their minds.