Signature Execution in Alzheimer's Disease: An Analysis of Motor Features

The analysis of signatures attributed to individuals with Alzheimer's disease (AD) poses special challenges to Forensic Handwriting Examiners (FHEs) and research on the subject has been scarce. The aim of the study was to assess how AD impacts motor features in signature execution through kinematic analysis. The study included 10 individuals with mild AD, 10 individuals with moderate AD and 10 healthy controls matched by age, education and gender. Eight hybrid signatures were collected from each participant using a digitizer and NeuroScript's MovAlyzeR (R) software. The study revealed no statistically significant intergroup differences regarding average absolute velocity, absolute jerk, normalized jerk and average pen pressure in the text-based that were produced. Findings suggest that, in text-based signatures, motor features are relatively preserved in the initial and moderate stages of Alzheimer's disease. Therefore, at these stages of the illness, FHEs should not expect significant changes in such features for this signature type. These results also support the hypothesis that motor programs responsible for the creation/execution of text-based signatures are not significantly impaired in the initial and moderate stages of the illness, due to the automation and lower cognitive demands of well-trained signatures.