The study involved 500 people age 50 to 85 with no dementia who lived in the Netherlands. They were asked about occasional memory problems such as having trouble thinking of the right word or forgetting things that happened in the last day or two, or thinking problems such as having trouble concentrating or thinking more slowly than they used to.

Study author Dr. Frank-Erik de Leeuw of Radboud University Nijmegen Medical Center, in the Netherlands, said brain scans were used to measure the size of the hippocampus, an area of the brain important for memory and one of the first areas damaged by Alzheimer's disease. Of the 500 people, 453 reported that they had occasional memory or thinking problems, which are also called subjective memory problems, because they would not show up on regular tests of memory and thinking skills.

The study, published in the journal Neurology, found that in people with occasional subjective memory problems, the hippocampus was smaller than in people who had no memory problems.