A simple blood test might reveal whether medications being used to treat Alzheimer’s disease actually are working, scientists have found.

Their study revealed that measuring blood levels of neurofilament light could determine whether nerve-cell damage in the brain is accelerating. Currently, there is no other noninvasive way to do this.

The study reinforces another investigation that showed that measuring neurofilament light in the blood could identify Alzheimer’s disease 10 years or more before symptoms actually appear.

Full findings appear in JAMA Neurology.