Tag Archives: Alzheimer’s disease

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Alzheimer’s disease: Patients benefit from nuclear imaging

(Vienna, 19 April 2018) With the help of Positron emission tomography (PET) Alzheimer“s disease (AD) can be detected long before the onset of the symptoms by making beta-amyloid in the brain visible. However, since there is still no cure for AD the question has been raised if such a diagnosis is really beneficial for the patient or rather more of a burden. First results of a large study, currently under way, show that PET diagnosis helped to improve medical management and counseling in over 65% of the patients. „AD patients clearly benefit from nuclear imaging,“ says Dr. Valentina Garibotto, expert of the European Association of Nuclear Medicine (EANM).

Alzheimer“s disease is the most frequent cause of dementia and one of the most important causes of disability in the elderly. The condition induces a decline in mental ability that usually develops and progresses slowly. Memory and judgment are impaired, and personality may deteriorate. The target of the PET examination is beta-amyloid, which is the chief component of plaques that are one of the hallmarks of Alzheimer“s. Recently developed tracers (radioactively labelled substances the patient is injected with) make these plaques visible on the computer screen. By applying this method the likelihood of Alzheimer“s disease can be established in patients with a higher degree of certainty, as compared with other routine diagnostic tools.

PET exams improve health care management
While its accuracy is uncontroversial the benefit of nuclear imaging for AD patients has frequently been questioned: Since there is no cure for this disease the gained diagnostic knowledge might be considered not only useless but an unnecessary psychological burden for the patient while he is still fit. In order to clarify this matter and to examine the actual impact of PET procedures on AD patient care and health outcome two large studies are currently under way: The IDEAS study (Imaging Dementia-Evidence for Amyloid Scanning) in the USA (www.ideas-study.org) and the AMYPAD study (Amyloid Imaging to prevent AD) in Europe (amypad.eu).

IDEAS started in 2016 and includes 18.000 participants. First results show that the outcome of PET scans have concrete beneficial consequences: They led to a change in medical and general health care management in around 65% of the patients. These changes consisted among other things in different drug prescriptions, making use of the fact that amyloid imaging allows doctors to determine with high accuracy whether in patients with mild symptoms Alzheimer“s is the cause or whether it can be excluded, so that some other kind of dementia or another condition has to be taken into account. Thus, depending on the PET exam results doctors changed to drugs specific for Alzheimer (namely aceltycholinesterase inhibitors) or they reversely abandoned these drugs in favor of a better suited medication, for exampleantidepressants or antipsychotics. PET scan results in favor of AD also induced an appropriate counseling about safety and future planning, thus helping patients and their friends and family to avoid preventable risks. For example, a diabetic who is also diagnosed with AD would not be left alone any longer to manage his insuline doses. „These interim results already provide convincing evidence that AD patients benefit largely from a more accurate diagnosis and we expect further study outcomes to complete the picture,“ says Dr. Valentina Garibotto of the EANM Neuroimaging Committee.

Nuclear imaging pivotal in AD research
Further important insights are to be expected of the AMYPAD study which has just started. This is a collaborative research initiative and part of the European Innovative Medicines Initiative (IMI). The overall goal of the program is to determine the value of amyloid PET imaging to diagnose and guide treatment, namely clinical trials, in AD. „Despite the hitherto unsatisfying results of therapeutic trials, our knowledge and understanding of AD has dramatically evolved over the last decades and PET imaging has played and still plays an increasingly central role. Accordingly, the next EANM focus meeting will be fully dedicated to the field of neuroimaging in AD. Entitled „Molecular Imaging of Dementia – The future is here“ it will invite worldwide experts to update the community on the latest developments,“says Dr. Garibotto.

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Medicine Wellness Health

Alzheimer’s disease: Early diagnosis through novel imaging technique

New nuclear imaging techniques make tau tangles in the brain visible

New nuclear imaging techniques help to detect a key factor involved in Alzheimer“s disease (AD) much earlier and more precisely than before. Recently developed tracers, used with positron emission tomography (PET) make tau tangles in the brain visible. For the first time these deposits which cause severe neuronal malfunctions can be identified and investigated „live“ in the brains of AD patients long before the onset of noticeable mental impairment. „This is an important step towards our goal to develop efficient drugs to fight and eventually cure AD“, says Dr Silvia Morbelli, expert of the European Association of Nuclear Medicine (EANM).
Many important details of the causes and the progress of AD remain to be elucidated. However, recent research results in the field of nuclear imaging have now brought about a major breakthrough in the diagnosis of the disease, raising hopes for early detection and targeted therapeutic approaches. Over the last few years, PET imaging has already enabled the visualization of -amyloid plaques (one of the hallmarks of AD) in the spaces between nerve cells. Now several recently developed PET tracers make it possible to track down tau deposits in the brains of AD patients too. Tau protein is an important building block of the so-called cytoskeleton, which is essential for the proper working of the nerve cells of the brain. In AD patients this protein undergoes changes that trigger the breakdown of the cytoskeleton. At the same time, unbound tau proteins clump together forming neurofibrillary tangles. The harmful impact of tau tangles on brain function is even more clearly established than that of beta-amyloid, making tau deposits a key suspect as a mediator of neurodegeneration. Before this recent breakthrough, these tau tangles could only be analyzed in post mortem brains.

Illuminating tau“s destructive potential
Based on these findings a neuroimaging research group of the University Hospital of Cologne (Germany) has now managed to precisely localize and measure tau tangles in AD patients and attribute them to corresponding neuronal malfunctions. The new tracers were used to measure tau tangles while also studying neuronal dysfunction with radioactively labelled glucose and amyloid tracers to measure amyloid plaques in the same subjects. A link between brain deposits and neuronal dysfunction could only be found for the tau tangles but not for amyloid plaques, thus highlighting the role of tau for the understanding of the development of AD. „The fact that the existing amyloid imaging technique is now able to be used in conjunction with tau imaging will allow us to study these events in patients in a much more comprehensive fashion“, says Dr Silvia Morbelli.

Opening up new treatment avenues
While imaging technologies are advancing rapidly, the development of effective treatments is still lagging behind. Against this backdrop amyloid imaging has already proven its value as it can identify plaques 10 to 15 years before the onset of cognitive symptoms. The same opportunity now exists for the detection of tau tangles. Even though there is no cure so far, certain medications can reduce the symptoms and thus preserve the patients“ mental abilities to a certain degree for a limited time span. „With the emergence of tau PET ligands, drug companies developing new therapeutics designed to halt or reverse AD now have the opportunity to test and monitor their drugs at an early stage of the disease process. The earlier a treatment is started, the greater are the chances of it being effective.“ says Prof Antony Gee, Chairman of the EANM Drug Development committee.
At present, many clinical trials evaluating potentially disease-modifying drugs only enroll AD patients who have been shown to have amyloid plaques using PET. However, with the discovery of tau PET tracers, alternative inclusion criteria can be considered expanded to tau tangles for the evaluation of new AD therapeutics. „Distinguishing more accurately between the clinical consequences of anti-tau and anti-amyloid effects will help to facilitate more effective and faster clinical trials. These are prerequisite for the identification of new AD therapies“, says Dr Silvia Morbelli.
Furthermore: The novel tau tracers are anticipated to help major breakthroughs for the investigation and diagnosis of non-AD related neurodegenerative diseases in which tau deposits play a similarly crucial role. This includes other types of dementia and parkinsonian syndrome.
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