Researchers attempting to detect Alzheimer’s at an early stage have created a simple test that combines thinking and movement to determine a person's risk. The test detects risk for dementia even before the onset of its usual symptoms.

The test, developed by Professor Lauren Sergio and Ph.D. candidate Kara Hawkins from York University, was made specifically for diagnosing Alzheimer's in patients who showed some difficulty in cognitive function, yet no signs of physical symptoms. For the test, participants had to complete four increasingly demanding visual-spatial and cognitive-motor tasks on dual screen computers.

"We included a task which involved moving a computer mouse in the opposite direction of a visual target on the screen, requiring the person's brain to think before and during their hand movements," Sergio said in a statement. "This is where we found the most pronounced difference between ... [the] mild cognitive impairment (MCI) and family history group, and the two control groups."

This test was based on the principle that most well-learned cognitive movements like walking or eating are preserved until the last stages of Alzheimer’s. It's when these movements require a person to think about them that a lapse in communication becomes evident, the researchers said. The study, “Visuomotor Impairments in Older Adults at Increased Alzheimer's Disease Risk,” was published in the Journal of Alzheimer's Disease.

For the test, the participants were divided into three groups: Those diagnosed with MCI or who had a family history of Alzheimer's disease, and two control groups in which one had young adults and the other had older adults without a family history of the disease. The study found that 81.8 percent of participants with a family history of Alzheimer's disease or already diagnosed with MCI showed difficulty completing the most cognitively demanding visual motor task.

"The brain's ability to take in visual and sensory information and transform that into physical movements requires communication between the parietal area at the back of the brain and the frontal regions," Sergio said "The impairments observed in the participants at increased risk of Alzheimer's disease may reflect inherent brain alteration or early neuropathology, which is disrupting reciprocal brain communication between hippocampal, parietal, and frontal brain regions."

Of course, this happens because of a build-up of plaques made of the protein beta-amyloid, which block nerve synapses and destroy brain cells by hampering communication between them. "In terms of being able to categorize the low Alzheimer's disease risk and the high Alzheimer's disease risk, we were able to do that quite well using these kinematic measures," Hawkins said. "This group had slower reaction time and movement time, as well as less accuracy and precision in their movements."

The scientists are quick to point out that while the tests can't predict who will develop Alzheimer’s, they can show slight variations in the brains of people diagnosed with MCI or with a family history of the disease.

Source: Sergio L, Hawkins K, et al. Visuomotor Impairments in Older Adults at Increased Alzheimer’s Disease Risk. Journal of Alzheimer's Disease. 2014.