New tool to detect early-stage Alzheimer's disease
Researchers in Germany and the US have discovered that a new molecular imaging agent could be used to diagnose Alzheimer's disease (AD) during its early stages. Presented at the 57th annual meeting of the Society for Nuclear Medicine in Salt Lake City, US, the results of the clinical trial represent a possible breakthrough for the early detection of AD, an incurable degenerative disease that currently affects an estimated 26 million people worldwide.
The symptoms of AD usually appear later in life, and are often mistaken for simple age-related changes. Inability to recall recent events, mood swings and confusion are just a few common symptoms. AD normally occurs in people over age 65, although early-onset AD also affects millions of people. Patient history is a major input for diagnosis, but this can be complicated as dementia takes on many different forms. Clinicians use advanced medical imaging techniques such as positron emission tomography (PET) to rule out other diseases; however, the diagnosis of AD can only be confirmed post-mortem.
"Early detection and treatment of Alzheimer's disease is essential and current methods of diagnosis, such as cognitive tests, are helping to catch the disease at its advanced stages, when the patient is already suffering from distinct cognitive impairments," explained Dr Osama Sabri of Leipzig University in Germany.
AD acts by destroying neurons throughout the brain, incapacitating memory centres and disrupting thinking. Motor skills and organ function are also affected by plaques made up of beta-amyloid proteins that appear in the brains of these patients. The exact cause is not known, but recent theories suggest that later in life, a close relative of the beta-amyloid protein may be involved in triggering the 'pruning' of neural connections. This is a process that normally happens only during early childhood, when streamlining such connections makes the brain work more efficiently.
This latest research shows that an imaging agent called Florbetaben binds directly to beta-amyloid, and can be used in PET molecular imaging to visualise the protein directly during the development of AD. By monitoring the clustering and spread of beta-amyloid, clinicians can follow the progression of the disease at cellular and molecular levels.
Participants in the clinical trial were 81 patients believed to have AD and 69 healthy subjects in 18 different research centres around the world, all of whom were aged over 55. The subjects' brains were imaged using Florbetaben with PET, and an area of the brain that was completely free of amyloid was selected as a reference. The researchers found that their technique was effective in diagnosing AD both visually and quantitatively.
"The imaging of beta-amyloid may assist clinicians in differentiating Alzheimer's disease from other types of dementia," Dr Sabri stated. "Additionally, this research will help to maximise the quality of life for patients who are still in the early stages of Alzheimer's and who still have the ability to play an active role in planning for the future."
Several agents are currently in development for beta-amyloid imaging, but Florbetaben shows promise for routine use because of its availability. It is hoped that by perfecting beta-amyloid imaging, scientists may be able to better target new drug treatments to slow the disease before irreparable damage and dementia sets in.
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