In the past, physicians were able only to follow the progression of Alzheimer's disease (AD) through careful clinical histories, noting the often subtle changes associated with cognitive decline over a number of years.
Recent research suggests that the use of molecular imaging in the management of neurodegenerative disease, particularly for early diagnosis of AD, will enable researchers to monitor the progression of the disease, identifying those at risk and assessing the effectiveness of new therapies.
Some studies have suggested that the characteristic signs of AD are present up to a decade before dementia sets in. The difficulty was being able to look into a living person's brain to see the deposits of plaque (an abnormal accumulation of insoluble fibrous beta-amyloid protein aggregates) thought to be responsible for the onset of the disease.
Using positron emission tomography (PET) and a radiotracer known as Pittsburgh Compound-B (PiB) that is capable of binding to plaques found in the brains of AD patients, researchers at the University of Pittsburgh found that beta-amyloid imaging could provide early detection of AD and more accurate differential diagnosis of other dementias (by revealing the presence or absence of beta-amyloid plaques).
In a current longitudinal study following participants for more than four years, the Pittsburgh research team has recently sought to compare patients with AD to elderly control individuals and to subjects with mild cognitive impairment (MCI) to determine control subjects at risk of developing cognitive impairment and those MCI subjects who were most likely to progress on to a clinical diagnosis of AD. Thirty-five people (four with mild to moderate AD, 10 with MCI and 21 elderly controls) were scanned at yearly intervals over four years.