A simple scratch-and-sniff test may someday help predict the onset of Alzheimer's disease among people suffering minor memory problems.
Researchers asked 77 people being evaluated for minor memory problems to identify 40 smells, such as menthol and peanuts, on scratch-and-sniff cards. Two years later, the scientists found that 19 of the 77 had been diagnosed with Alzheimer's.
Of those with the disease, 16 had scored particularly poorly on the scratch-and-sniff tests—and were unaware of their limited ability to smell. Overall, the people who were unaware of their loss of smell were 13 times more likely to develop Alzheimer's disease than were people with normal smelling capability or those aware of their olfactory limitations, report Davangere P. Devanand of Columbia University and his colleagues in the September American Journal of Psychiatry.
Alzheimer's disease is known to damage the nerves involved in identifying scents, says Elisabeth Koss of th