Atypical Visually Guided Precision Grip Control in Middle-Aged and Older Autistic Adults

Sensorimotor impairments are well documented in autism spectrum disorder (ASD). However, little is known about how these difficulties present in middle-aged and older autistic adults or how they relate to demographic factors and autistic traits. In this study, 52 autistic and 56 age- and sex-matched non-autistic adults (aged 30-73 years) completed a visually guided precision grip task designed to assess temporal (reaction time, duration), spatial (force accuracy, variability), and dynamic (rate of force change) features of grip control under two conditions: varying motor output demands (target force test) and visual feedback (visual gain test). Autistic adults showed prolonged duration, delayed reaction time, and greater target overshooting at lower force levels during the rise phase. During the sustained phase, they exhibited increased grip force variability across both tasks. In contrast, autistic adults demonstrated shorter reaction times during the relaxation phase. Subgroup analyses revealed that the middle-aged autistic subgroup displayed elevated grip force variability, whereas the older autistic subgroup showed broader impairments affecting both spatial and temporal aspects of precision gripping. Within the autistic group, temporal grip force variables under the low target force condition were significantly associated with age and repetitive behaviors. These findings demonstrate that manual motor impairments persist into adulthood in ASD, and suggest shared neurobiological networks that underlie both motor dysfunction and core autistic traits.