Researchers from the Mayo Clinic have found a biomarker that may indicate the probability of the development of Alzheimer’s disease in humans.

The study collected blood tests for 99 women aged 70 to 79, who had heretofore been free of dementia. In particular, researchers were testing for levels of ceramides, a certain compound in fat. Researchers followed them for nine years, over which time 27 women developed dementia. In that group, 18 women had showed samples of the biomarkers.

According to the study published in Neurology, “Previous studies have shown that high serum ceramides are associated with memory impairment and hippocampal volume loss, but have not examined dementia as an outcome.” They found that women with higher levels of the fatty compound were 10 times more likely to develop dementia in the nine-year period. Researchers also tested for sphingomyelins, though there did not seem to be a correlation between levels of sphingomyelins and risk of dementia.

The study did have some limitations. The sample size was small; 99 study participants is not necessarily indicative of the population as a whole. There were no men studied either, which may beg the question of whether the compound has the same tendency to predict Alzheimer's development in men as well as women.

Researchers are also left with a host of questions. Mainly, study authors wonder whether low levels of ceramides reduce the risk of dementia, rather than high levels of ceramides having any indication of whether those people will have dementia. In addition, the study authors do not answer the question of whether all women with the biomarker developed dementia, and were unable to verify if levels of ceramides would have the same correlation for people tested earlier in life.

The development of a noninvasive blood test that can trace biomarkers for Alzheimer’s disease would be a gold mine for scientists. With the disease currently affecting 35.6 million people today, and set to increase to 115.4 million by 2050, it would be immensely helpful for people, governments, and medicine to know just who would develop the disease. There is currently no way to predict the onset of Alzheimer’s disease – or any form of dementia – until symptoms start appearing.

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