Applause sign in advanced Parkinson's disease.

Background: The 'applause sign' a tendency to continue applauding in response to instructions to clap three times was described in 1995 and was considered specific to degenerative disease, especially to atypical parkinsonian disorders. In early phase Parkinson's disease (PD) the sign has been reported positive as well. In late stage PD it is unknown whether and to what extent the sign may be elicited and it remains unknown if and to what degree the sign correlates to cognitive impairment and PD related dementia.

Methods: Nursing home residents with PD (MMSE >17) were included. All patients underwent the clapping test and were tested for cognitive disturbance by making use of accepted clinimetrics (MMSE and Scopa-cog). T-testing was performed with the hypothesis that patients expressing the applause sign would score lower on the MMSE or Scopa-cog.

Results: Seventy three nursing home residents (mainly Hoehn and Yahr 4/5) with a mean disease duration of 10 years and a mean age of 78.7 years were included. The applause sign was found positive in 15 of 73 residents (20.5%). Residents expressing the applause sign had significantly lower mean scores on the MMSE (25.1 vs 22.9 points, p < 0.006) and Scopa-cog (14.8 vs 12.0 points, p < 0.039).

Conclusions: The applause sign is present in late stage PD and correlates with a higher degree of cognitive impairment as established with accepted clinimetric tests. A higher degree of frontal lobe involvement explains the presence of the applause sign.