Alzheimer's disease is a progressive and fatal brain disorder named for German physician Alois Alzheimer, who first described it in 1906. Alzheimer's destroys brain cells, causing problems with memory, thinking and behavior severe enough to affect work, lifelong hobbies or social life. Alzheimer’s gets worse over time, and it is fatal.

The progression of the disease is a growing concern. It's estimated that more than 5 million Americans have Alzheimer's disease — about one in 10 of those aged 65 and older and nearly half those 85 or older.  Today it is the seventh-leading cause of death in the US. The number afflicted could more than triple, to 16 million, by 2050 based on current projections. 

Early Detection is Key

Because the incidence of (Alzheimer's disease and related disorders) is expected to increase dramatically as the baby boomer generation ages, accurate diagnosis is extremely important -- particularly at the early and mild stages of dementia when lifestyle changes and therapeutic interventions would be most effective.

Early diagnosis can also allow those affected and their families more time to plan for their care and to get needed things in order. A computer-assisted imaging technique that measures sugar metabolism within a critical area of the brain could hold the key to the early diagnosis of Alzheimer's disease and other dementias.

The study was done by researchers at Center for Brain Health, NYU Medical Center, New York. The study included 548 people examined at seven separate centers who were mostly in their 60s and 70s. The participants had either no evidence of cognitive decline, mild cognitive impairment, Alzheimer's disease, or dementia due to other causes, confirmed through a battery of neurological and psychological tests.

Each patient was injected with the radioactive isotope FDG, which mimicked glucose once it entered the body. After about 30 minutes researchers began taking pictures of the brain using positron emission tomography (PET), to scan the brain. The images were later analyzed using the computer program developed at NYU.

By comparing images of the cerebral cortex at the brain's surface to those of the hippocampus deep within the brain, the researchers could accurately distinguish between patients with normal brain function and specific dementias, including  Alzheimer's disease.

PET imaging enabled the researchers to highlight glucose consumption patterns within the hippocampus and identify specific images associated with normal brain function, mild cognitive impairment that did not meet the criteria for dementia, and different types of dementias, including Alzheimer's disease. The hippocampus is associated with learning and memory, metabolizes glucose (the fuel for the brain) less efficiently as dementia progresses.

The computer-assessed imaging model also appeared to predict which type of dementia someone with mild cognitive impairment would eventually have as well as identifying brain patterns associated with very early cognitive decline. This specificity raises hopes that the imaging model might lead to earlier diagnosis and better outcomes among patients with Alzheimer's disease and other dementias.

According to the researchers, the technique has an accuracy of 94% in distinguishing Alzheimer's disease from other dementias. he researchers are now evaluating follow-up data on the patients in the study to determine how accurate the imaging was at predicting their clinical course. The next step after this is to examine the imaging technique outside the clinical trials setting.

The study was published in the March 2008 issue of the Journal of Nuclear Medicine.

SOURCE: Mosconi, L., The Journal of Nuclear Medicine, March 2008; vol 49: pp 390-398.