Neuroimaging may shed light on how Alzheimer's disease develops

January 11, 2010

Current Alzheimer's disease (AD) research indicates that accumulation of amyloid-beta (Aβ) protein plaques in the brain is central to the development of AD. Unfortunately, presence of these plaques is typically confirmed only at autopsy. In a special issue of the journal Behavioural Neurology, researchers review the evidence that Positron Emission Tomography (PET) can image these plaques during life. This exciting new technique provides researchers with an opportunity to test the amyloid hypothesis as it occurs in living patients.

In a review article with over 100 references, Dr. Gil Rabinovici and Dr. William Jagust from the University of California, San Francisco and Berkeley, summarize the results of experiments from their laboratories and others using the Aβ tracer Pittsburgh Compound-B (PIB). This compound binds to Aβ protein and allows the mapping of plaques in the brains of AD and non-AD volunteer subjects.

They report that PIB-PET can detect Aβ deposits in a significant proportion of cognitively normal older subjects and that these deposits are associated with brain atrophy even in the absence of cognitive symptoms. By the time patients develop mild cognitive impairment (MCI) amyloid load in the brain appears to have reached a plateau. As patients progress to dementia, neurodegeneration and cognitive decline proceed independently of further amyloid accumulation.

The authors interpret these results as consistent with a model in which amyloid deposition plays a critical early role on the path to AD, beginning years before onset of symptoms and triggering a series of events which ultimately leads to cognitive decline and dementia.

While the use of PIB-PET is currently limited to research centers because of the compound's very short radioactive half-life (20 minutes), new amyloid imaging agents with longer half-lives are under development for more widespread use. Amyloid imaging is already playing an important role in the development of amyloid-based therapies for AD, and Dr. Rabinovici and Dr. Jagust speculate that in the future amyloid imaging will assist clinicians in identifying patients with mild or atypical symptoms who may be candidates for anti-amyloid treatments.

Writing in the article, the authors state, "PIB-PET has provided us with our first in vivo glance at the dynamic relationship between amyloid deposition, clinical symptoms, and structural and functional changes in the brain in the continuum between normal aging and AD…In the future, Aβ imaging will likely supplement clinical evaluation in selecting patients for anti-amyloid therapies both during drug development and in the clinic."

More information: The article is "Amyloid imaging in aging and dementia: Testing the amyloid hypothesis in vivo" by G.D. Rabinovici and W.J. Jagust. It appears in Behavioural Neurology, Vol. 21, Issues 1-2 (2009), published by IOS Press.

Related Stories

Recommended for you

Neurons can learn temporal patterns

May 29, 2017

Individual neurons can learn not only single responses to a particular signal, but also a series of reactions at precisely timed intervals. This is what emerges from a study at Lund University in Sweden.

People match confidence levels to make decisions in groups

May 26, 2017

When trying to make a decision with another person, people tend to match their confidence levels, which can backfire if one person has more expertise than the other, finds a new study led by UCL and University of Oxford researchers.

Optic probes shed light on binge-eating

May 26, 2017

Activating neurons in an area of the brain not previously associated with feeding can produce binge-eating behavior in mice, a new Yale study finds.

Study finds gray matter density increases during adolescence

May 26, 2017

For years, the common narrative in human developmental neuroimaging has been that gray matter in the brain - the tissue found in regions of the brain responsible for muscle control, sensory perception such as seeing and hearing, ...

Game study not playing around with PTSD relief

May 26, 2017

Post-traumatic stress disorder (PTSD) patients wrestling with one of its main symptoms may find long-term relief beyond medication thanks to the work of a Western researcher.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.