Autonomic Nervous System Function and Sensory Sensitivity in 12-Month-Old Infants with the FMR1 Premutation

Area of Science:

• Neuroscience
• Genetics
• Developmental Psychology

Background:

• Fragile X premutation (FXpm) involves expanded CGG repeats in the FMR1 gene.
• FXpm is linked to sensory processing and autonomic regulation challenges in children and infants.
• The relationship between autonomic nervous system (ANS) function, molecular variables, and sensory responsiveness in infancy remains understudied.

Purpose of the Study:

• To investigate parent-reported sensory responsiveness in 12-month-old infants with FXpm compared to neurotypical (NT) controls.
• To examine associations between sensory responsiveness and autonomic measures (respiratory sinus arrhythmia [RSA], interbeat interval [IBI]) in infancy.
• To explore the relationship between CGG repeat length and sensory responsiveness in infants with FXpm.

Main Methods:

• Recruited 12-month-old infants: 35 with FXpm and 55 NT controls.
• Assessed parent-reported sensory responsiveness.
• Measured baseline RSA and IBI as indicators of ANS functioning.
• Recorded CGG repeat length in the FMR1 gene for the FXpm group.

Main Results:

• No significant differences in hyporesponsive or hyperresponsive sensory behaviors were found between FXpm and NT infants.
• No significant associations were observed between baseline RSA or IBI and sensory responsiveness in either group.
• Within the FXpm group, a longer CGG repeat length correlated with lower scores for hyperresponsive sensory behaviors.

Conclusions:

• Behavioral manifestations of sensory processing differences may not be apparent in infants with FXpm at 12 months.
• Biological variability, indicated by CGG repeat length, shows an early association with sensory responsiveness in FXpm.
• Further research is needed to understand genetic and physiological factors influencing later behavioral phenotypes in early FXpm development.