Cognigram can detect early signs of MCI and Alzheimer’s disease

Jan 15 2014

For patients over the age of 50, a routine physical exam at the doctor’s office typically covers a wide spectrum of medical biomarkers with one glaring exception, cognitive health. Unless there have been unusual mental changes or challenges in their daily life, tests of a patient’s attention, memory or brain processing speed is usually not part of a check-up.

To detect the early, subtle signs of mild cognitive impairment (MCI) which may lead to forms of dementia, including Alzheimer’s disease, there is a need for a standardized test that can alert physicians to a possible cognitive decline. Last week, research from the Florey Institute of Neuroscience and Mental Health in Australia reported that a brief, online set of cognitive tests, commercially known as Cognigram, can detect early signs of MCI and Alzheimer’s.

Cognigram has been developed by Cogstate, a leading medical technology company specialising in cognitive assessment and training. 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, physicians need to observe performance on several key domains. 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 by Paul Maruff PhD, Chief Science Officer of Cogstate, was able to compare test results with traditional hallmarks of MCI and AD.

“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 AD which emphasize that cognitive impairment characteristic of both prodromal and clinically classified AD is disruption to memory and executive function,” said Dr Maruff.

To test this, they recruited volunteers from the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study, dividing them into three groups; 653 healthy adults, 107 with amnesic MCI (where the primary symptom is memory loss), and 44 with AD. 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 simply answer a yes/no question about what and when cards are shown to them. For the attention/reaction composite, volunteers completed the Detection task, pressing a certain key on a computer keyboard as soon as a card is turned over, as well as the Identification task, answering yes or no if a card turned over is the color 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.

As hypothesized by the research team, the results showed that both the MCI and the AD groups performed significantly worse on both composites than the healthy adults. Also, the AD group’s learning/memory score was significantly lower than the MCI group, demonstrating the presence and progression of the memory decline caused by the disease.

To be a reliable diagnostic tool for physicians, 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.

The full study can be accessed online at BMC Psychology.

“We are excited about the results of this study,” said 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.”