New Way to Study the Mental Capabilities of Children Over 12 With PA or MMA

Propionic and Methylmalonic Acidemia are metabolic diseases that often come with developmental delays and disabilities in mental capabilities. About half of the children studied with PA have either delays in motor skills (like walking) or in the ability to speak. In studies of children with MMA, their tests of understanding, reasoning, and memory showed lower scores. It is important to note that, in surveys of children with PA, their responses showed that they felt generally healthy and similar to their peers.

Researchers are working on clinical studies for new treatments that may have a positive effect on mental capabilities, but need to be able to prove, by some type of measurement, that there is an improvement in understanding, remembering, thinking, reasoning, and paying attention before and after the study’s treatment.

A recent study assessing different ways to measure these abilities, specifically in people with PA and MMA, found one interesting approach that seemed to be better at it.

The “Cookie Theft Picture Task” provides a specific picture to stimulate spontaneous speech about that image, which can demonstrate the ability to understand, reason, and express thoughts verbally. The test was designed for individuals ages 12 years and older.

A picture is shown of a mother washing dishes and two children, one of whom is reaching for a cookie while standing on a stool that is about to tip over. The person being tested is asked, “Tell me everything you see going on in this picture.” Their responses are recorded and then analyzed according to various measures. Most adults complete this test in 1–2 minutes. All participants ages 12 years and older were able to complete the Cookie Theft Picture Task. The analysis was able to show any weakness in the capabilities necessary to understand and respond verbally to the questions about the picture.

Until recently, little attention has been given to how people with metabolic disorders, like PA and MMA, are able to speak about their observations and understanding of what they experience or see. Researchers believe that this capability may be sensitive to small changes in toxic metabolite levels on a day-to-day basis and may have an important influence on day-to-day functioning.

In other words, researchers believe that changes in how children are engaging in conversations about their perceptions may have the potential to serve as markers that reveal subtle symptoms in PA and MMA. Studies in linguistics reveal that spontaneous speech involves motor abilities, as well as coordination, speed of thinking processes, and rapid use of working memory. These are areas that are known to be particularly affected in PA and MMA.

Source: Chapman K.A. et al. Molecular Genetics and Metabolism Reports 34 (2023) 100953

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