A study of facial expression in Parkinson's disease using a novel microcomputer-based method.

The aim of this study was to compare the smiling behaviour of a group of Parkinson's disease sufferers with a control group of a similar age using a novel microcomputer-based approach, which utilises a mathematical model of the face to quantify facial expression. The findings indicate that the Parkinson's group differed from the control group in the frequency of smiling while watching a series of cartoons and in the degree of mouth opening during smiling. Both groups completed the Levine-Pilowsky Depression questionnaire, and patients with Parkinson's disease had significantly higher depression scores than those of the control group. Significant negative correlations between depression score and frequency of smiling, and depression score and inner eyebrow separation were also found.