Measure of Cognitive Function Reliable for People With Intellectual Disabilities

Researchers have found that a battery of tests may be able to measure cognitive changes over time in people with intellectual disabilities; these measurements may be able to identify whether special drugs and programs are effective in improving function in this population (J Neurodev Disord. 2016;8[1]:35).

This work has the potential to open new doors to research into whether drugs and specialized educational programs or treatments can improve function in people with Down syndrome, fragile X syndrome, and other causes of intellectual disabilities.

In a statement, lead study author David R Hessl, PhD, University of California David MIND Institute, said that findings, if validated in a larger study currently under way, could change the course of research on treatments for intellectual disabilities and other neurodevelopmental disorders, particularly in the area of drug therapy.
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The study used the National Institutes of Health Toolbox Cognitive Battery (NIH-TCB), developed in young children, adolescents, and adults from the general population, to determine whether it would reliably measure change in cognitive function in people with intellectual disabilities, who tend to be very difficult to accurately assess.

Participants included people of varying ages with fragile X syndrome, Down syndrome, and other causes of intellectual disabilities, including those with autism. They were enrolled in three studies that examined tests to measure cognitive flexibility, inhibition and visual attention, episodic memory, working memory, processing speed, oral reading, and receptive vocabulary, calculating each person’s performance relative to his or her age-matched peers from the general population.

After performing extensive analyses, the pilot studies showed that, overall, the NIH-TCB is feasible, reliable, and valid as a cognitive measurement tool for a high proportion of participants. Examination of ecological validity also revealed moderate to very strong correlations between the NIH-TCB composite and adaptive behavior and full-scale IQ measures.

Dr Hessl cautions that the findings are based on pilot studies involving relatively small numbers of participants and are not yet ready for use in clinical trials or other applications. He and his colleagues are currently in the first of a four-year, multi-site study of the tests on a larger scale and over a longer time period.—Amanda Del Signore