HPA axis function predicts development of working memory in boys with FXS

Area of Science:

• Neuroscience
• Developmental Psychology
• Genetics

Background:

• Fragile X syndrome (FXS) is a genetic disorder associated with cognitive impairments.
• Understanding the developmental trajectory of cognitive functions, like verbal working memory, in FXS is crucial.
• The role of physiological stress markers, such as cortisol, in cognitive development within FXS is not fully understood.

Purpose of the Study:

• To examine longitudinal changes in verbal working memory in boys with FXS compared to typically developing (TD) controls.
• To investigate the relationship between cortisol levels and verbal working memory performance over time in boys with FXS.
• To elucidate the interplay between biological stress mechanisms and cognitive development in FXS.

Main Methods:

• Longitudinal study design with assessments over a 2-year period (1-3 assessments per participant).
• Inclusion of boys with FXS and nonverbal mental-age (NVMA) matched TD boys.
• Utilized two verbal working memory tasks of varying complexity (memory for words, auditory working memory) and salivary cortisol measurements.

Main Results:

• Boys with FXS demonstrated specific longitudinal deficits in memory for words compared to TD controls.
• Elevated baseline cortisol exacerbated verbal working memory deficits in boys with FXS on the memory for words task.
• While both groups showed similar growth rates in auditory working memory, higher baseline cortisol was associated with lower performance in boys with FXS.

Conclusions:

• Verbal working memory development in boys with FXS is characterized by specific deficits, particularly in tasks requiring word recall.
• Cortisol, a marker of physiological stress, significantly impacts verbal working memory performance in boys with FXS.
• Investigating the dynamic interactions between biological factors (cortisol) and cognitive development (verbal working memory) is essential for understanding FXS.