Analysis of dementia in aged subjects through chaos analysis of fingertip pulse waves

The fingertip pulse waves (plethysmograms) of 179 elderly people were measured and chaos analysis were performed on these waves to calculate the largest Lyapunov exponent, we acquired dementia data and ADL index recorded by healthcare professionals for the same subjects. We discovered a significant relationship between the value of the largest Lyapunov exponent and the degree of dementia and also communication skill. The relationship is displayed as a constellation graph of the time series.