Boys with Duchenne muscular dystrophy (DMD) typically have a dip in executive function skills beginning in middle childhood that begins to rise again during the preteen years, according to a study recently published in Neuromuscular Disorders.
Executive function means the mental skills needed for everyday tasks, and entails the regulation of thoughts, emotions and actions. It can be divided into “hot” and “cold” categories. “Hot” executive function encompasses tasks in which emotions run high, such as risky decision-making. Meanwhile, “cold” executive function refers to tasks with little emotion attached, such as working memory.
Researchers sought to investigate the development of both hot and cold executive functioning in boys with DMD. They enrolled 70 boys between 5 and 14 years of age. Recruited participants underwent standardized measurements assessing motor function (i.e., the functional ability of the upper and lower limbs) and cognitive abilities.
Read more about DMD testing and diagnosis
The researchers found that at age 5, the boys had no executive function impairments. But there was a pronounced decline in hot executive function between 5 and 8 years of age.
A steep decline in cold executive function was seen between 8 and 11 years of age. Cold executive function was indicative of developmental delay, rather than developmental decline.
“Both hot and cold EF skills reached their lowest levels at 11 years of age,” the study’s authors wrote. But by 14, executive function rose toward the age-related norm again.
A longitudinal study (a study conducted by following up with patients over a period of time) also showed that there were significant differences in working memory between 5 and 8 years of age.
“Clinically, these findings highlight the importance of adopting a proactive, individualized approach that considers the complex developmental trajectory of boys with DMD, addressing both the development of hot and cold [executive function] skills,” the authors of the study concluded.
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