"We're getting a better understanding of the complex constellation of factors that change [in the brain] with aging," said Howard Hughes Medical Institute researcher Randy L. Buckner of Washington University in St. Louis. "When you start to look across the literature, lots of data points converge suggesting there are certain changes that take place in aging that are not what cause Alzheimer's disease."
Buckner is the author of a review article published in the September 30, 2004, issue of Neuron, that points out recurring distinctions between factors that influence what he calls executive function, which more commonly falters with normal aging, and the decline in long-term memory typical of Alzheimer's. Executive function involves the cognitive processes used to complete complex, goal-oriented tasks. Elderly individuals with no symptoms of dementia may have difficulty attending to one thing when distractions are present, for example, or they may experience difficulties in complex, novel situations.
Buckner says the data suggest that changes in executive function are due to age-associated influences on frontal-striatal circuits of the brain, including an area called the corpus callosum a tract of white matter that connects the two cerebral hemispheres. The accelerated memory loss of Alzheimer's disease is more likely due to changes in the medial temporal lobe memory system, which includes the hippocampus.
For brain changes in non-demented aging, Buckner reviews studies that use structural magnetic resonance imaging (MRI) images
Contact: Jim Keeley
Howard Hughes Medical Institute