Alzheimer's Disease and Signature Execution
Keywords:Alzheimer's Disease, Handwriting changes and senility, Signatures, Static features
Alzheimer´s disease (AD) is a progressive and irreversible neurodegenerative disease involving the impairment of several cognitive functions. To determine how AD affects signatures, samples from three groups were analysed: DA1 (17 participants with a medical diagnosis of AD; Mini-Mental State Examination Test (MMSE) 20.12 ± 2.00); DA2 (17 participants with a medical diagnosis of AD; MMSE 11.06 ± 3.93) and a control group (30 healthy matched individuals; MMSE 28.07 ± 1.60). General features (Chi-Square Tests Linear-by-Linear Association, p <0,050) and constructional features (Fischer’s Exact Test, p <0,050) were analysed. Statistically significant differences between the AD groups and the control group were found in legibility, tremor and line quality, spacing between words and shape and direction of the baseline. Although no statistical differences were found in size among the three groups, cases of micrographia and macrographia were found exclusively in DA2. Statistically significant differences were not found in velocity, level of connection, and pressure. In constructional features, repetitions (often as perseverations or uncontrolled repetitions of strokes or letters), omissions, and substitutions (some in the form of allographic agraphia) were present. Some individuals in the AD groups also included additional writings in their signatures. These results may be associated with the overall cognitive deterioration that occurs in AD. FDEs should be aware that these changes may be common in the handwriting of AD patients, particularly in more severe stages. Therefore, interpreting the occurrence of tremor, decrease in line quality and other changes in the handwriting features mentioned above should be made with caution. Obtaining both earlier and contemporaneous signatures should also assist FDEs to better interpret tremor and other alterations in the handwriting of AD patients, and to evaluate if these are naturally occurring changes due to the progression of the illness or simulations.
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