Magazine article Clinical Psychiatry News

Brain Imaging Shows Early Alzheimer-Like Changes

Magazine article Clinical Psychiatry News

Brain Imaging Shows Early Alzheimer-Like Changes

Article excerpt

TUCSON, ARIZ. -- Brain imaging techniques are giving researchers invaluable clues in the understanding of Alzheimer's disease well before symptoms appear.

Such techniques may offer the chance to test promising ways to prevent the disorder without having to wait many years to determine whether or when study participants develop memory and thinking problems, reported Dr. Eric M. Reiman at a psychopharmacology conference sponsored by the University of Arizona.

Scientists have begun to track the progression of brain changes in cognitively normal carriers of the apolipoprotein E (APOE) [epsilon]4 allele, a common Alzheimer's susceptibility gene, said Dr. Reiman, professor of psychiatry at the University of Arizona in Tucson and director of the Arizona Alzheimer's Disease Consortium.

Drug makers are increasingly interested in the use of imaging techniques to test drugs designed to treat and prevent Alzheimer's disease. In clinically affected patients, these techniques provide a way to test the effectiveness of drugs being used to slow the progression of brain disease.

Imaging techniques also permit manufacturers to test treatments in a shorter period of time using smaller numbers of patients. In cognitively normal APOE [epsilon]4 carriers, the techniques make it possible to evaluate prevention therapies for their effectiveness in slowing brain changes.

The two techniques that are best established for such purposes are volumetric MRI, which measures changes in brain volume, and fluorodeoxyglucose positron emission tomography (PET), which measures glucose metabolism over time.

Volumetric MRI has been particularly useful in tracking rates of atrophy in the hippocampus and entorhinal cortex, regions of the brain that are critical to recognition and recall memory, and in tracking rates of atrophy in the whole brain in Alzheimer's patients. Manual measurements have been helpful, but researchers continue to work on fully automated methods, which are less labor intensive and make it easier to compare findings from different laboratories.

In that regard, Dr. Reiman described a completely automated method of "subtracting" sequential MRIs obtained from the same Alzheimer's patient to track changes in total brain volume over a 1-year period.

Fluorodeoxyglucose PET has been useful in revealing reductions in brain activity in parts of the brain where these reductions become more pronounced as the Alzheimer's disease becomes more severe. …

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