Researchers are discovering subtle changes in different areas of the brain that may be early clues to the onset of Alzheimer’s. The findings could lead to earlier diagnosis of the disease, which doctors are coming to realize may affect the brain years before memory loss and thinking difficulties become prominent. Earlier diagnosis could in turn lead to more effective treatments, since drugs and other therapies may be most effective before the disease has extensively damaged the brain.
The findings were presented in two studies at the Neuroscience 2010 annual meeting in San Diego, a gathering of brain researchers sponsored by the Society for Neuroscience. "Identifying those at risk for Alzheimer's and developing new treatments for nervous system disorders is a social imperative," said Sam Sisodia, Ph.D., of the University of Chicago, an expert on the cellular biology of proteins implicated in Alzheimer's disease. "These studies are evidence that we're making real progress to overcome this tragic epidemic."
In one study, researchers at the University of California, Los Angeles (UCLA), reported that people with Alzheimer’s disease exhibit striking structural changes in an area of the brain called the caudate nucleus. This brain structure is typically associated with movement disorders like Parkinson’s disease, rather than Alzheimer’s.
"Our finding suggests that Alzheimer’s disease produces broader damage in the brain than previously thought, including damage to areas not usually associated with the disease," said lead author Sarah Madsen, a graduate student at the university.
For the study, the California researchers studied the brains of 400 elderly men and women. A quarter were healthy, a quarter had been diagnosed Alzheimer’s disease, and half had mild cognitive impairment, a condition that causes serious memory loss and sometimes leads to Alzheimer’s disease.
In those with Alzheimer’s, the caudate nucleus was 7 percent smaller than in those with intact memories. It was 4 percent smaller in those with mild cognitive impairment. It was also smaller in seniors who were older and overweight.
"Our finding suggests a gradual progression of brain tissue loss in the caudate nucleus as dementia becomes more severe," said Ms. Madsen. "This brain area, which is associated with certain forms of learning and memory as well as motor control, is an important factor to consider when studying Alzheimer’s disease and in predicting how the disease will progress," she said.
In another study, researchers at Rush University Medical Center in Chicago used MRI brain scans to locate brain changes that seemed to predict the onset of Alzheimer’s disease. MRI, or magnetic resonance imaging, is a form of scanning that uses magnetic tools rather than radiation. The experts did periodic scans on 52 seniors with mild cognitive impairment over six years. During that time, 23 were given a diagnosis of Alzheimer’s disease.
The researchers focused on an area that lies deep within the brain called the substantia innominata, which sends chemical signals to the cerebral cortex, the outer layer of the brain that plays a big part in reasoning and memory. The scans did not show any structural changes in the substantia innominata in those with memory problems, but they did show thinning in the cortical areas that receive signals from the SI in those who developed Alzheimer’s.
"Our findings support the notion that structural imaging techniques can be used to identify people at risk for developing Alzheimer’s disease," said co-author Sarah George, a graduate student at Rush. "MRI screening appears to be a strong candidate for an early biomarker of Alzheimer’s disease."
Researchers continue to focus on MRI and other imaging techniques in the hopes of finding ways to detect Alzheimer’s early. “"One of the main challenges in the field of Alzheimer's disease is identifying individuals at risk of developing Alzheimer's disease so that therapeutic interventions developed in the future can be given at the earliest stage before symptoms begin to appear," Ms. George said.
Source: Neuroscience 2010 Annual Meeting, San Diego, Calif. http://www.sfn.org/am2010/index.aspx?pagename=abstracts_main