A new study suggests more than half of people who develop Alzheimer's disease before the age of 60 are initially misdiagnosed as having other kinds of neurological disease when they do not have memory problems. The research is published in the May 17, 2011, print issue of NeurologyR, the medical journal of the American Academy of Neurology.

For the study, researchers reviewed the cases of 40 people from the Neurological Tissue Bank-University of Barcelona-Hospital Clinic-IDIBAPS, Barcelona, Spain, whose brains showed that they had Alzheimer's disease in an autopsy. Researchers also reviewed information about the age at which the symptoms began and family history.

About 38 percent experienced initial symptoms other than memory problems.

The study found that one-third of people with confirmed early onset Alzheimer's disease showed symptoms other than memory problems, such as 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 four percent of those who had memory problems. They were mainly diagnosed 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," said study author Albert Llado, M.D., Ph.D., with the Alzheimer's Disease and Other Cognitive Disorders Unit, Hospital Clinic of Barcelona and the Institute of Biomedical Investigation August Pi i Sunyer (IDIBAPS), in Barcelona, Spain. "Biomarkers of Alzheimer's disease and other disorders are needed for us to better recognize, diagnose and treat early onset Alzheimer's disease sooner to improve the quality of life of these patients."

The study was supported by a grant from the Hospital Clinic-Emili Letang.