A global research team has shown that men whose red blood cells are lacking a Y chromosome – a phenomenon known as loss of Y – may be more susceptible to developing Alzheimer’s. The researchers believe that the loss of Y could be a biomarker for Alzheimer’s, allowing physicians to diagnose the disease in its early stages.

The Y chromosome contains the genetic information necessary for many of the factors that make an individual physiologically male – including development of the testes – but in some men, their Y chromosome begins to degenerate as they age. As men tend to live shorter lives compared to women, and men are more likely to develop non-sex-linked cancers, this loss of Y may explain the differences in mortality between the sexes.

In order to investigate the potential link between loss of Y and Alzheimer’s, Professors Lars Forsberg and Jan Dumanski, from the Department of Immunology, Genetics, and Pathology at Uppsala University, Sweden, set up a collaboration with researchers in the UK, France, the US and Canada. Forsberg’s previous research interests included determining what effects the loss of the Y chromosome had on cancer development and progression.

“The idea for this research project came to me when I was writing our first paper on the relationship between loss of Y and the development of non-blood cancers,” said Forsberg. “In thinking about the process known as immunosurveillance – the body’s ability to fight disease development throughout life – I found that it had been well studied in Alzheimer’s disease, and hence it occurred to me that loss of Y might be involved in this disease too.”

The researchers studied the prevalence of Y chromosomes in the red blood cells of 3,300 men aged 37 to 96. Approximately 17 percent of the men showed a loss of Y in a minimum of 10 percent of their red blood cells.

The researchers found that elderly men more commonly displayed loss of Y. While the study contained a wide age range, the average age for study participants was 73.

Individuals with a pre-existing Alzheimer’s diagnosis were more likely to have a loss of Y. Interestingly, those identified as having a loss of Y were more likely to develop Alzheimer’s in the follow-up period after the study.

The researchers suggest that the degraded Y chromosome may lower the red blood cell’s ability to function during an immune response. Regardless, the researchers say that loss of Y could act as a biomarker to encourage physicians to begin neurological testing for Alzheimer’s.

More than 5 million people suffer from Alzheimer’s in the US alone; this number is expected to rise to 14 million by 2050.