A 15-minute home test can reveal the first signs of Alzheimer's disease according to US researchers.
Health older people can take the test and then share the results with doctors.
Of 1,000 over-50s who took the test, 28% were revealed to have cognitive impairment which is a mild loss of mental function.
Detailed medical diagnostic tests were carried out on the same same group of people and the results were very similar.
The questions in the test include basic mathematical questions like: How much change from £5 would you get if you spent £1.95.
They also inclue general knowledge questions including: Name 12 different types of fruit or vegetabales.
Dr Marie Janson, Director of Development at Alzheimer’s Research UK, the UK’s leading dementia research charity, said: “Diagnosing dementia in its earliest stages is hugely important, not least because a diagnosis can open the door to care and treatments as early as possible.
"The ability to diagnose people early is also a key target for research, to allow new treatments to be tested on the right groups of people at the right time. Dementia can be difficult to diagnose, especially in the early stages, and anyone who is worried about their memory should talk their GP.
"We need to wait for the results of trials of this test before we’ll know whether it can be used in the thousands of GP clinics across the country.
“Alzheimer’s Research UK continues to support projects and invest in this important area of research. With over 820,000 people in the UK affected by dementia, and an ageing population, the need for research has never been more pressing.”