MONDAY, May 16 (HealthDay News) -- More than half of those who develop Alzheimer's disease before the age of 60 are initially misdiagnosed when the first signs of the disease are symptoms other than memory problems, a small study suggests.

Spanish researchers reviewed the cases of 40 people from Barcelona who were found to have Alzheimer's disease in autopsy reports. Researchers also reviewed information about the age at which the symptoms began, as well as the patients' family history.

About 38 percent of early onset Alzheimer's patients experienced initial symptoms other than memory loss. Those symptoms included behavior, vision or language problems, and a decline in executive function or the ability to carry out tasks.

In people with atypical symptoms and no memory problems, 53 percent were incorrectly diagnosed when first seen by a doctor, compared to only 4 percent of those who did have memory problems.

Those with undetected early onset Alzheimer's were mainly misdiagnosed with other types of dementia. Of those with unusual initial symptoms, 47 percent were still incorrectly diagnosed at the time of their death.

"People who develop early onset Alzheimer's disease often experience these atypical symptoms rather than memory problems, which can make getting an accurate diagnosis difficult," study author Dr. Albert Llado, with the Alzheimer's Disease and Other Cognitive Disorders Unit in the Hospital Clinic of Barcelona and the Institute of Biomedical Investigation August Pi i Sunyer in Barcelona, said in an American Academy of Neurology news release.

The research is published in the May 17 issue of Neurology.

More information

The U.S. Centers for Disease Control and Prevention has more information on Alzheimer's disease.