Dec. 23, 2003 Irvine, Calif. -- UC Irvine College of Medicine researchers conducting the first longitudinal brain imaging study of adults with Down syndrome may have found a way to detect Alzheimer's disease before symptoms of dementia begin to set in.
In the study, brain scans of adults with Down syndrome showed increased metabolic activity in the temporal cortex – the same region of the brain where Alzheimer's disease commonly develops. The researchers speculate that Alzheimer's may begin with a similar metabolic increase, because Down syndrome often leads to dementia during adulthood
If so, a common PET scan procedure could allow early detection of Alzheimer's.
Study results appear in the Dec. 23 issue of Neurology.
According to Richard Haier, professor of pediatrics and principal investigator of the study, neurons work efficiently in normal brains, but in diseased brains, damaged neurons have to work harder to maintain their effectiveness, as revealed by the metabolic rate increases in Down syndrome brains. This damage most likely comes from the progressive accumulation of both senile plaques and neurofibrillary tangles, the two lesions associated with both Down syndrome and Alzheimer's. When the damaged neurons are ultimately destroyed by these lesions, the metabolic rate will decrease, as was observed in the Alzheimer's-diseased brains scanned for the study.
"These findings suggest that Down syndrome dementia and possibly Alzheimer's disease may begin when neuronal damage in the temporal cortex region reaches the point where increased metabolism can no longer compensate," Haier said. "But to confirm this, further imaging tests must be done on the Down syndrome people as dementia progresses."
Nearly 350,000 Americans have Down syndrome, which is a genetic disorder caused by the inheritance of three copies of the 21st chromosome. People with Down syndrome show some of the brain changes of Alzheimer's as early as age 12. Nearly all Down syndrome patients have the brain changes of Alzheimer's disease by age 40. Despite this, not all individuals with Down syndrome develop symptoms of the disorder.
The National Institute of Child Health and Development is providing funding for this study.
Dr. Michael Alkire, Nathan White, Melina Uncapher, Elizabeth Head, Dr. Ira Lott and Carl Cotman of UCI assisted Haier with the study.
About the University of California, Irvine: The University of California, Irvine is a top-ranked public university dedicated to research, scholarship and community. Founded in 1965, UCI has more than 23,000 undergraduate and graduate students and about 1,300 faculty members. The third-largest employer in dynamic Orange County, UCI contributes an annual economic impact of $3 billion.
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