A study from Australia, published online first in BMC Psychology, has confirmed the effectiveness a new test for Alzheimer’s disease. The test is said to detect cognitive decline in patients by scoring attention/reaction and learning/memory and comparing the scores to traditional cognitive impairment indicators
To detect the early signs of mild cognitive impairment which may lead to forms of dementia, including Alzheimer’s disease, there is a need for a standardised test that can alert physicians to a possible cognitive decline, it says in a press release. Recent research from the Florey Institute of Neuroscience and Mental Health in Australia reported that a brief, online set of cognitive tests (Cognigram; Cogstate) can detect early signs of mild cognitive impairment and Alzheimer’s.
According to the release, Cognigram is available to primary-care physicians to provide a dementia test at the point of care in Canada through an exclusive agreement with Merck Canada. More than 580 primary care physicians have registered to use Cognigram and 20 testing centres are now live.
To evaluate the functional health of a human brain, there needs to be observation of performance on several key domains, it states in the release. To assess the state of sub cortical brain regions including the basal ganglia as well as cortical regions such as the prefrontal and parietal cortices, tests of attention and reaction time are used. Learning and working memory depend on normal functioning of the hippocampus and temporal lobe (for pattern separation) and prefrontal cortex and anterior cingulate (for working memory).
By grouping these two domains, attention/reaction and learning/memory, into composite scores, the research team, led Paul Maruff, chief science officer of Cogstate, were able to compare test results with traditional indicators of mild cognitive impairment and Alzheimer’s.
“The presence of a relatively greater impairment in cognitive functions dependent on cortical and limbic brain regions (i.e. learning and working memory) with relatively subtle impairment in motor and attention functions is consistent with neuropsychological models of Alzheimer’s disease which emphasise that cognitive impairment characteristic of both prodromal and clinically classified Alzheimer’s disease is disruption to memory and executive function,” says Maruff.
To test this, they recruited volunteers from the AIBL (Australian imaging, biomarkers and lifestyle) study, dividing them into three groups; 653 healthy adults, 107 with amnesic mild cognitive impairment (where the primary symptom is memory loss), and 44 with Alzheimer’s disease. They were all asked to complete the four tests of the Cogstate brief battery (also known as Cognigram), and the speed and accuracy of the results were recorded.
All of the Cogstate tests use a deck of playing cards as their focus point. No knowledge of any card games is required, patients answer a yes/no question about what and when cards are shown to them. For the attention/reaction composite, volunteers completed a detection task, pressing a certain key on a computer keyboard as soon as a card is turned over, as well as an identification task, answering yes or no if a card turned over is the colour red.
For the learning/working memory composite, two additional tests were used. The one-card learning task asks, “Have you seen this card before in this task?” To test immediate recall, the one back test asks if the card displayed is the same as the immediately prior card.
The results showed that both the mild cognitive impairment and the Alzheimer’s disease groups performed significantly worse on both composites than the healthy adults. Also, the Alzheimer’s group’s learning/memory score was significantly lower than the cognitive impairment group, demonstrating the presence and progression of the memory decline caused by the disease.
To be a reliable diagnostic tool for physicians, it says in the release, the test battery needs to be able to show consistent results over time. The Cognigram testing was repeated four times in three months and showed statistically similar results across all groups.
“We are excited about the results of this study,” comments Maruff. “The Cogstate brief battery has been found to be sensitive to amyloid-related cognitive change in many trials. This study shows for the first time, that a version of the test designed specifically for clinical practice; the Cognigram battery, has excellent sensitivity and specificity to mild cognitive impairment.”
