Abstract

Background: Motor control issues are common for people with intellectual disabilities (PWID), resulting in difficulties with basic activities of daily living, including eating. Mastication, which is crucial for digestion and overall health, is poorly understood in this population. PWID shows frailty similar to older people, highlighting the importance of comparing masticatory motor control with older adults. This study compared the neuromuscular control of the masticatory muscles in middle-aged, PWID and older adults. Methods: A cross-sectional analytical design was used. During the mastication task of a carrot piece (2 cm in diameter and weighing 0.5 g), surface electromyography was used to record muscle activity patterns from the right and left masseter and temporalis muscles. Principal component analysis (PCA) was used to assess neuromuscular control. A z-score normalisation of the first component's variance from PCA to identify those individuals with altered neuromuscular control. A mixed ANOVA was performed to assess the interaction between principal components, groups and body composition. Results: Thirty PWIDs (aged 35-55 years), middle-aged adults and 32 older adults were recruited. PWID and older adults showed decreased neuromuscular control of the masticatory muscles compared to middle-aged control adults (P < 0.05). PWID had the highest proportion of individuals with altered neuromuscular control of the masticatory muscle (53%) compared to older adults (19%) and middle-aged adults (0%) (P < 0.05). Conclusions: Our results indicate that PWID and older adults have reduced neuromuscular control compared to middle-aged adults. Notably, a significant proportion of the PWID showed altered masticatory muscle control compared to older adults. Further research is needed to explore the potential benefits of masticatory muscle training for PWID.