Distinctive Features of Bimanual Coordination in Idiopathic Normal Pressure Hydrocephalus

Background Idiopathic normal pressure hydrocephalus (iNPH) is characterized by cerebrospinal fluid circulation disorders, and presents as gait and balance disturbances similar to those observed in other incurable neurological diseases. Although previous studies have reported deficits in bimanual coordination among patients with iNPH, these potential pathological characteristics have not received much attention to date. This study investigated the temporal characteristics of a bimanual finger-tapping task in patients with iNPH, focusing on within- and between-hand coordination. Methods Study participants comprised three groups: patients with iNPH (N = 19, mean age = 76.9 ± 5.6 years), older adults (N = 19, 76.4 ± 5.3 years), and younger adults (N = 13, 32.2 ± 8.5 years). Participants performed a bimanual finger-tapping task under five conditions that manipulated the temporal differences between the two taps. Results The iNPH group exhibited significantly greater errors in both within- and between-hand coordination tasks compared to the other two groups. Conclusion The observed increase in errors in between-hand coordination in the older group compared to the younger group, suggests that between-hand coordination is susceptible to aging. These findings show that evaluating temporal errors in a bimanual coordination task, particularly for within-hand coordination, is potentially useful for uncovering pathological characteristics specific to iNPH.