Current testing methods are only 77% accurate in helping to predict how safe it is for people who have mild dementia to drive, according to a study published in the Journal of the American Geriatrics Society.

The authors, from Macquarie University in Sydney, Australia, reached their conclusion after reviewing 28 various testing methods, among them mental status tests, on-road assessments, tests using computerized and simulated driving, and those using motor vehicle crash data.

People with dementia are two to eight times more likely than adults of the same age without dementia to be involved in car accidents, according to the researchers. Until test accuracy can be improved, they said, older adults and their family members should continue to work with doctors, nurses, social workers and other experts, who can evaluate the abilities of older adult drivers and help them transition to “driver retirement” when the time appears to be right.