Finger dexterity measured by the Grooved Pegboard test indexes Parkinson's motor severity in a tremor-independent manner.

Fine motor impairments are frequent complaints in people with Parkinson's disease (PD). While they may develop at an early stage of the disease, they become more problematic as the disease progresses. Tremors and fine motor symptoms may seem related, but evidence suggests two distinct phenomena. The purpose of our study was to investigate the relationships between fine motor skills and clinical characteristics of PD patients. We hypothesized worse fine motor skills to be associated with greater motor severity that is independent of tremor. We measured fine motor abilities using the Grooved Pegboard test (GPT) in each hand separately and collected clinical and demographics data in a cohort of 82 persons with PD. We performed regression analyses between GPT scores and a range of outcomes: motor severity, time from diagnosis, age and tremors. We also explored similar associations using finger and hand dexterity scores from a standardized PD rating scale. Our results indicate that scores on the GPT for each hand, as measures of manual dexterity, are associated with motor severity and time from diagnosis. The presence of tremors was not a confounding factor, as hypothesized, but age was associated with GPT scores for the dominant hand. Motor severity was also associated with hand and finger dexterity as measured by single items from the clinical Parkinson's rating scale. These findings suggest that the GPT to be useful tool for motor severity assessments of people with PD.