Unique graphic characters called “Greebles” may prove to be valuable tools in detecting signs of Alzheimer’s disease (AD) decades before symptoms become apparent, according to a study published in the Journal of Alzheimer’s Disease.

The research showed that cognitively normal people who have a genetic predisposition for AD have more difficulty distinguishing among these novel figures than individuals without genetic predisposition.

AD is characterized by the presence of beta amyloid plaques and tau neurofibrillary tangles in the brain. Tau tangles predictably develop first in the perirhinal and entorhinal cortices of the brain, areas that play a role in visual recognition and memory. The researchers developed cognitive tests designed to detect subtle deficiencies in these cognitive functions. They hoped to determine whether changes in these functions would indicate the presence of tau tangles before they could be detected through imaging or general cognitive testing.

Subjects ranged in age from 40-60 and were considered at-risk for AD due to having at least one biological parent diagnosed with the disease. A control group of individuals in the same age range whose immediate family history did not include AD was also tested.

The subjects completed a series of “odd-man-out” tasks in which they were shown sets of four images depicting real-world objects, human faces, scenes and Greebles in which one image was slightly different than the other three. The subjects were asked to identify the image that was different.

The at-risk and control groups performed at similar levels for the objects, faces and scenes. For the Greebles, however, the at-risk group scored lower in their ability to identify differences in the images. Individuals in the at-risk group correctly identified the distinct Greebles 78 percent of the time, whereas the control group correctly identified the odd Greeble 87 percent of the time.

The scientists say that they would like to see further research to determine whether the individuals who performed poorly on the test actually developed AD in the future.

Paper: “Family History of Alzheimer’s Disease is Associated with Impaired Perceptual Discrimination of Novel Objects”
Reprinted from materials provided by the University of Louisville.