As more and more people are diagnosed with dementia in ageing populations, the need for research has become acute. But how can demented people give informed consent to potentially risky procedures? Few people make advance directives for instructions on their participation in clinical trials in the event of a decline into dementia. So surrogates have to make a decision for them. What kind of risks would these surrogates consent to for their spouse or parent?

This was a question posed by doctors from the University of Michigan in the journal Neurology recently. They interviewed 229 people who were at risk of Alzheimer’s and found 90% acceptance for the lowest risk studies such as scientists making observations, conducting interviews or taking blood. And even for the riskiest procedures, such as inserting new genes into the brain, about half approved.

However, doctors warn that it will still not be easy to recruit people for dementia research. The figures in the Michigan survey may be unrealistically high, because people are normally more willing to accept risks for themselves than for someone else. Furthermore, the demented patients have to cooperate. “If I’m doing a brain scan, I can’t tie down a person and put them in a scanner against their will,” says Dr William Jagust, of University of California at Berkeley. “It’s not ethical.”