February 27, 2008
People who spend fewer years in school may be slower to realize that they are suffering from the early symptoms of Alzheimer's disease than those who are more highly educated, a new report found. The lag may explain why, overall, less educated people tend to be diagnosed with Alzheimer's at a slightly later age than those who are highly educated. At the same time, problems with memory and thinking may have advanced further by the time those with little schooling are diagnosed with the disease.
The findings, published in the Archives of Neurology, come from scientists at the Alzheimer's Research Center at Washington University School of Medicine in St. Louis. The researchers reviewed data on nearly 1,500 Alzheimer's patients from their center. They also reviewed files on more than 21,000 patients from the National Alzheimer's Coordinating Center, a collaboration of approximately 30 Alzheimer's disease research centers nationwide.
"We may have a group of people who are at risk for slightly delayed detection of Alzheimer's disease," said lead author Catherine Roe, Ph.D., a neurology research instructor at Washington University. "Early detection of Alzheimer's disease is important as we progress toward treatments and cures because those treatments will need to be applied as early as possible to have the maximum possible benefit."
The new study revealed that patients with 12 years or more of schooling were on average slightly younger when diagnosed with Alzheimer's disease than patients with less than eight years of schooling. Age of diagnosis for a group with eight to 11 years of schooling fell in-between the other two groups.
The researchers also analyzed the severity of patients' dementia when they went to the Alzheimer's disease center for the first time. They found that patients with fewer years of education were likely to be more severely impaired on their first visit.
Fewer years of formal schooling have been linked to an increased risk for Alzheimer's in earlier studies. Higher levels of education, on the other hand, may be protective. One theory is that education helps build a strong network of interconnections between nerve cells in the brain. This network may act as a so-called "brain reserve," allowing the brain to function normally as cells die from Alzheimer's.
Why would someone with more schooling, then, be diagnosed with Alzheimer's sooner?
The researchers propose that those with lower education levels may be slower to notice the early signs of disease, only going to see a specialist after their symptoms become impossible to ignore. Those with more education, on the other hand, may become aware of their symptoms while they are still relatively subtle and seek a specialists' help early on in the disease process.
"People with higher education levels may be more likely to have a job or a hobby that makes early cognitive impairment more obvious, as well as better access to medical care," Dr. Roe said. "These could be factors that we need to incorporate into our procedures for screening patients for early signs of cognitive impairment."
Roe CM, Xiong C, Grant E, Miller JP, Morris JC: "Education and Reported Onset of Symptoms among individuals with Alzheimer's disease." Archives of Neurology, January 2008. Washington University School of Medicine news release.