Brain Scan Predicts the Development of Alzheimer’s Dementia

Brain scan may detect the brain amyloid levels to estimate the time until Alzheimer’s dementia symptoms appear as per a study “Predicting symptom onset in late onset Alzheimer disease with amyloid PET” , at the Washington University School Of Medicine in St. Louis, published online in the journal Neurology. Dementia is an umbrella term for a range of neurodegenerative disease, characterized by gradual loss of memory and thought process that interferes with daily life. Alzheimer's disease is the most common type of dementia.

Alzheimer's disease (AD) is characterized by gradual memory loss and behavioral changes that occur because of the formation of beta-amyloid plaques in the brain tissues, years before the actual symptoms occur.

The study team designed an algorithm from the data of brain scans – amyloid positron emission tomography (PET) of 236 patients with an average of 67 years. The measure of the brain levels of beta-amyloid protein was done using a widely used metric known as the standard uptake value ratio (SUVR) to the scans.

Algorithm and PET Scan

“I perform amyloid PET scans for research studies, and when I tell cognitively normal individuals about positive results, the first question is always, ‘How long do I have until I get dementia?’ Until now, the answer I’d have to give was something like, ‘You have an increased risk of developing dementia in the next five years.’ But what does that mean? Individuals want to know when they are likely to develop symptoms, not just whether they are at higher risk,” says senior author Suzanne Schindler, MD, Ph.D., an assistant professor of neurology.

The study aimed to estimate the time when a person has no cognitive symptoms but is likely to develop Alzheimer’s disease. The Amyloid PET scans are extensively used for Alzheimer’s research.

However, the present approach represents a new way of analyzing such scans using a person’s age and data to further point out when the symptoms will arise.

“When we look at the brains of relatively young people who have died with Alzheimer’s, they typically look pretty healthy, other than Alzheimer’s. But older people more frequently have damage to the brain from other causes, so their cognitive reserves are lower, and it takes less amyloid to cause impairment,” says, Schindler.

The study thereby states that amyloid accumulation has a tipping point and that each individual hits that tipping point at a different age. After this tipping point, amyloid accumulation follows a reliable trajectory.

One may reach the tipping point even in their 50s or 80s. But once this tipping point passes, the accumulation of amyloid levels escalates up and up. Hence, predicting the time point where one would hit their tipping point may further help predict the likeliness of developing AD symptoms.

Source-Medindia