The successful design of musical interventions for dementia patients requires knowledge of how rhythmic abilities change with disease severity. In this study, we tested the impact of the severity of the neurocognitive disorders (NCD) on the socioemotional and motor responses to music in three groups of patients with Major NCD, Mild NCD, or No NCD. Patients were asked to tap to a metronomic or musical rhythm while facing a live musician or through a video. We recorded their emotional facial reactions and their sensorimotor synchronization (SMS) abilities. Patients with No NCD or Mild NCD expressed positive socioemotional reactions to music, but patients with Major NCD did not, indicating a decrease in the positive emotional impact of music at this stage of the disease. SMS to a metronome was less regular and less precise in patients with a Major NCD than in patients with No NCD or Mild NCD, which was not the case when tapping with music, particularly in the presence of a live musician, suggesting the relevance of live performance for patients with Major NCD. These findings suggest that the socioemotional and motor reactions to music are negatively affected by the progression of the NCD.