Positron emission tomography using fluoro-deoxyglucose can detect a reduction in glucose metabolism in the hippocampus of normal elderly people that appears to be a marker for development of dementia, according to a presentation at the first Alzheimer's Association International Conference on Prevention of Dementia.

"Earlier identification of Alzheimer's may enable earlier treatment and empower people to plan for their future sooner, including financial and legal matters," said William Thies, PhD, vice president, Medical and Scientific Affairs at the Alzheimer's Association. "Yet a large proportion of people with dementia are not diagnosed until the disease is in the moderate or advanced stages. As better treatments and prevention strategies emerge, this situation has to change. The Alzheimer's Association, the National Institute on Aging and industry are pushing hard for earlier detection and earlier intervention."

In the current study, Lisa Mosconi, PhD, and her American colleagues examined 53 normal elderly subjects (average age, 67 years, range 50-84) who completed a longitudinal study using Positron Emission Tomography, PET) with fluoro-deoxyglucose (FDG) to study brain glucose metabolism.

Glucose metabolism is the major energy source of the brain and is a sensitive indicator of brain damage. Subjects were followed for a period ranging from 10 to 24 years with a total of two or three PET scans. At the end of the study, six subjects had declined to Alzheimer's and 19 showed mild cognitive impairment.

At baseline, reductions in glucose metabolism in the brain's hippocampus were found for the study participants who would eventually decline to Alzheimer's or mild cognitive impairment compared with people who retained cognitive function. Measurements taken at the beginning of the study predicted clinical outcome with a sensitivity of 83 percent for Alzheimer's disease cases and 79 percent for mild cognitive impairment. The follow-up measures yielded equivalent prediction accuracy.

"This is the first brain imaging study to demonstrate detection of sporadic Alzheimer's disease in normal elderly subjects," Mosconi said. "This data suggests that the recognition of future Alzheimer's disease in a person who is cognitively normal is a realistic goal."

Individuals diagnosed in the Mosconi study and other research presented at the meeting said that there were positive aspects of being diagnosed, including having the time to plan for the future and focus on what is important to them, along with getting access to resources such as support groups and research studies. People in the study who were diagnosed in the earliest stages of memory loss were able to manage the symptoms of memory loss quite well.

"Although the disease involves many serious problems for diagnosed individuals and their families, Alzheimer's usually progresses slowly and there is typically a substantial time before a person needs assistance," one expert said. "During this period, how others interact with people who have been diagnosed is especially important."

"Early detection of Alzheimer's has granted researchers access to a population of people who are able to articulate their experiences and needs. By understanding the experiences of being tested and living with memory loss, we can significantly improve clinical practice. It is critical to continue exploring the individual, social, and bioethical consequences of increasingly earlier diagnoses."