On Apr. 14, 2014, Stanford Medicine researchers announced a study that found a gene variant puts women at higher risk of Alzheimer’s than it does men. The scientists arrived at their findings by analyzing records on more than 8,000 people, most of them older than 60, who have been monitored over time at any one of about 30 Alzheimer’s centers nationwide.

The researchers analyzed clinical assessments of 5,000 people whose test results were normal at the outset and 2,200 people who had initially showed signs of mild cognitive impairment. In both groups, being an ApoE4 carrier increased the likelihood of Alzheimer’s disease, as expected. But a closer look revealed that among those who initially tested normal, this increased risk was only marginal for men, whereas women who carried the ApoE4 variant had close to twice the likelihood of progressing to mild cognitive impairment or Alzheimer’s disease as those who didn’t.

The discovery holds implications for genetic counselors, clinicians and individual patients, as well as for clinical-trial designers. It could also help shed light on the underlying causes of Alzheimer’s disease, a progressive neurological syndrome that robs its victims of their memory and ability to reason. The study was published in the Annals of Neurology.