It is common for older people to forget things. Now an American study has found that memory starts to fail when we are young adults. People younger than thirty years of age usually do not know that they are starting to forget information. But scientists from the University of Michigan say the loss of memory has usually already started. Researchers say people do not observe this slow reduction in mental ability until the loss affects their everyday activities. Denise Park led the new study. She directs the Centre for Aging and Cognition at the Institute for Social Research at the University of Michigan. Her team studied more than 350 men and women between the ages of twenty and ninety years. The study identified people in their middle twenties with memory problems. She says young adults do not know they are forgetting things because their brains have more information than they need. But she says that people in their twenties and thirties are losing memory at the same rate as people in their sixties and seventies. Ms. Park says people between the ages of sixty and seventy may note the decrease in their mental abilities. They begin to observe that they are having more trouble remembering and learning new information. The study found that older adults are more likely to remember false information as being true. For example, they remembered false medical claims as being true. Younger people remembered hearing the information. But they were more likely to remember that it was false. Ms. Park is now using modern imaging equipment to study what happens in the brains of people of different ages. She is studying what parts of the brain older adults use for different activities compared to younger adults. Ms. Park says mental performance is a direct result of brain activity and brain structure. She says keeping the brain active is important. She hopes future studies will identify ways to improve the operation of our aging minds. According to the passage, young adults differ from older adults in that   _  .
they lose their memory at a slower rate they rarely realize they have memory problems their brains can store much more information all of the above