Narrator:       This is Science Today. Positron emission tomography, or PET scans, have been a valuable tool for neuroscientists studying the brain — especially when looking for clues about disease development. Susan Landau, a researcher at the University of California, Berkeley, has used PET scans to measure the biochemistry of the brain in a study that identified an early biomarker for the eventual development of Alzheimer's disease.

Landau:         It looks like as different parts of the brain show deterioration, as neural degeneration develops, glucose metabolism, or how well the brain is working, how efficiently the brain is working, that declines.

Narrator:       Their study focused on participants with mild cognitive impairment and Landau says it seems that it may be too late for treatment to be effective in individuals already showing decline.

Landau:         So, where we'd like to go is start moving earlier and earlier in the disease spectrum and hopefully target people who haven't experienced any decline and target them for potential participation in clinical trials and more research.

Narrator:       For Science Today, I'm Larissa Branin.