Applause sign in Alzheimer's disease: relationships to cognitive profile and severity of illness.

The present study aims to investigate the potential clinical utility of applause sign in Alzheimer's disease (AD), exploring whether it is consequent to the severity of cognitive impairment or to specific neuropsychological profiles. According to the current debate, the role of apraxia is also investigated. A total of 105 patients with AD were enrolled and classified on the basis of the severity of the disease: 37 had mild AD, 38 moderate AD, and 30 severe AD. They were compared to 42 normal subjects. The applause sign was detected using the three clap test. All patients underwent a broad neuropsychological examination and 95 AD patients were tested for the presence of apraxia with a detailed praxis battery. Applause sign was present in all AD patient groups, which showed a significant difference with respect to normal controls, but not between each other. No significant difference was reported between apraxic and non-apraxic patients. Applause sign correlated with measures of frontal lobe dysfunction. No correlations were found between the applause sign and other cognitive functions examined.