Deficits in motor performance have been well documented in individuals with Down syndrome (DS). However, only a few studies have focused on manipulative skills and older adults in this population. Given the associations between manipulative skills and daily living activities, more work is needed to examine the aging effect on individuals with DS. A total of 54 adults with DS participated in this study. The results indicated that older participants showed more lateralization than younger participants. They exhibited superior dominant hand preference compared to younger participants. In addition, participants with DS with high verbal ability had better performance in manual dexterity and handgrip force. Therefore, in the clinical setting, assessing mental age may help in identifying individuals with DS at a higher risk of motor impairment. Future work should examine additional determinants with a large sample size to understand the development of manipulative skills in individuals with DS. Furthermore, additional studies are needed to investigate the associations between mental age and other cognitive functions and motor performance in this population.