New Cognitive Screening Test May Help Diagnose Dementia Earlier

Amy Taylor November 18, 2013

Researchers from Johns Hopkins University believed that they have developed a model that could determine whether memory loss experienced by older adults is benign or a precursor to Alzheimer’s disease.

Mild cognitive impairment, defined as a noticeable and measurable decline in intellectual abilities that does not seriously interfere with daily life, is considered a ‘risk factor’ for dementia. However, physicians have no reliable way to determine whether people with cognitive impairment are likely to suffer from dementia. At present, only 5 to 10 per cent of people with this condition progress into Alzheimer’s.

For the study, the researchers analyzed the records of 528 people ages 60 and above, who were referred to the Johns Hopkins Medical Psychology Clinic for cognitive testing as part of a dementia work-up between 1996 and 2004. The results were compared with the records of 135 healthy older adults who were part of the study on normal aging. Both groups completed tests of memory, language, attention, processing speed and drawing abilities from which 13 scores were recorded.

Because each of the participants has higher skill levels in some areas than the others, the scores of healthy adults showed a symmetrical, bell-shaped range. That is, most of their scores were high, a few were a bit lower, and a few were even lower. But by grouping the participants into cohorts based on the severity of their dementia, the researchers found a trend in the test scores. Such trend is likely to mimic the deterioration of an individual’s scores over time.

David J. Schretlen, the study lead author and a professor of psychiatry and behavioural sciences at the Johns Hopkins University School of Medicine, explained that at the outset, Alzheimer’s disease subtly disrupts some mental abilities, while leaving others intact. Thus, well before a person develops clear cognitive impairment, his or her performance declines slightly on a few measures. When shown on a graph, these changes cause the healthy symmetric, bell-shaped curve to shift and become asymmetrical.

Their findings show that regardless of the patients’ scores, their score distribution correlated with dementia. The researchers predicted that people with low scores that were evenly distributed were not likely to develop dementia whilst those with lopsided test score distribution on the 13 measures administered were already experiencing varying levels of dementia.

If confirmed by future studies, this new statistical model could help doctors get the prognosis right earlier in the disease, at the first visit, and start treating patients accordingly, Schretlen added.

Their work was published in the journal Neuropsychology.

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John Hopkins research may improve early detection of dementia