Alzheimer’s disease is a progressive degenerative disease that results in a loss of brain cells. It is the most common form of dementia, affecting 60-80 % of people with dementia above 65 years of age. The most common symptoms of Alzheimer’s dementia are memory impairment, confusion, disorientation in time and place, difficulties with communication and everyday tasks.

In people with Alzheimer’s disease, the brain undergoes changes, including the accumulation of proteins called ‘ß-amyloid’ and Tau in the brain. The accumulation of ß-amyloid and Tau can start more than a decade before clinical symptoms of dementia occur. Although there is no preventive or curative treatment for Alzheimer’s disease yet, researchers are investigating possible interventions to delay the onset of disease. These interventions would then be used by healthy persons during the long ‘preclinical’ period, that is: before any symptoms of Alzheimer’s disease occur.

During the last few years, new conceptual approaches and criteria to describe Alzheimer’s disease have been developed referring to the spectrum of Alzheimer’s disease in three stages: (1) preclinical Alzheimer’s disease, (2) mild cognitive impairment (MCI) due to Alzheimer’s disease, and (3) dementia due to Alzheimer’s disease.

Read more about the changing definition of Alzheimer’s disease

One pathological hallmark of Alzheimer’s disease is the accumulation of ß-amyloid, called ‘amyloid plaques’, in the brain, caused by the overproduction of ß-amyloid and/or the failure of clearance mechanisms. In a healthy brain, the peptide ß-amyloid is broken down and eliminated. In people who develop Alzheimer’s disease, ß-amyloid accumulates between brain cells, interfering with their normal functioning and their connections to other brain cells. Thus, this peptide represents an important therapeutic target for Alzheimer’s disease: if ß-amyloid can again be broken down.

Watch the EPAD amyloid video to know more about ß-amyloid:

Positron Emission Tomography (PET) is a type of neuroimaging, which allows for the visualisation of the amyloid plaques in the brain. It uses small amounts of radioactive materials called tracers. These tracers are ‘attached’ to particular compounds of interest in the brain and injected into the body. A scanner detects signals from the tracer to see how much of the compound of interest is in the brain.

PET tracers have recently been approved for marketing, which allows for wider use of PET imaging to detect ß-amyloid accumulation in the brain. AMYPAD used two ß-amyloid PET tracers, which are called florbetaben and flutemetamol. As commercial products, they are called NEURACEQ^TM and VIZAMYL^TM. 

Watch the video developed by Alzheimer’s Society to know how a PET scan is performed

The Amyloid imaging to prevent Alzheimer’s disease (AMYPAD) project aimed to determine the clinical utility of ß-amyloid PET imaging for the understanding, diagnosis and management of Alzheimer’s disease. Moreover, in combination with the European Prevention of Alzheimer’s disease (EPAD) study and other non-EPAD cohorts, the project aimed at unraveling the natural history of the disease in the preclinical or presymptomatic stage to assess the predictive value of ß-amyloid PET and ensure correct enrollment of patients into targeted treatment trials.

The first signs of Alzheimer’s disease (i.e. the accumulation of ß-amyloid) can be found in the brain decades before the first symptoms appear. However, ß-amyloid deposition is considered to be a necessary, but not sufficient, step on the path towards the development of Alzheimer’s dementia. The role of ß-amyloid in diagnosing Alzheimer’s disease in its early stages has not yet been fully clarified. AMYPAD assessed whether depiction of brain ß-amyloid can improve the prediction or early diagnosis of Alzheimer’s disease. A good way to assess brain ß-amyloid is PET imaging.

The AMYPAD diagnostic study selected and followed up a clinical population suspected of possible Alzheimer’s disease, focusing on those with subjective cognitive decline and mild cognitive impairment (MCI), to determine the usefulness of ß-amyloid imaging as a diagnostic marker for Alzheimer’s disease.

Researchers believe that intervention at the earliest possible stage of the disease may be an effective way to prevent or reduce the development of Alzheimer’s dementia from the asymptomatic stage or the stage of subjective cognitive decline or mild cognitive impairment (MCI).

For this purpose, the AMYPAD prognostic study has analysed ß-amyloid PET scans from a large population of healthy research participants and research participants who are at the earliest stages of Alzheimer’s disease, to understand the window of opportunity for secondary prevention through ß-amyloid imaging.

AMYPAD worked closely with the EPAD project (www.ep-ad.org), which worked to increase the understanding of the early stages of Alzheimer’s disease and creating a platform to test treatments designed to prevent dementia. The AMYPAD Prognostic and Natural History Study (PNHS) was planned as a sub-study of the EPAD Longitudinal Cohort Study (LCS). AMYPAD PNHS was evaluated how amyloid imaging might help improve the understanding of the natural course of Alzheimer’s disease. In this study, participants enrolled in the EPAD LCS underwent PET amyloid imaging.

The AMYPAD PNHS study heledp improve the understanding of disease pathophysiology. Also it gathered information about research participants, notably about the presence of biomarkers for Alzheimer’s disease, which can be used to select research participants for clinical trials. Also, it made the inclusion of research participants in clinical trials more efficient: participants from various Parent Cohorts had the advantage of having already been well-characterized by previous assessments. This prevents the undue inclusion in Alzheimer’s dementia prevention trials of people who are unlikely to develop Alzheimer’s dementia.

It is not possible to register on an individual basis for participation in the AMYPAD studies. In fact, potential AMYPAD participants were recruited from existing population studies and memory clinic cohorts only.

The recruitment process has been completed for the AMYPAD Diagnostic and Prognostic studies.