Objective: To define objective handwriting change in Parkinson’s disease (PD) with emphasis on the early stages.

Background: Handwriting is a complex activity that requires precision and dexterity. Writing difficulties usually present as an early symptom of PD. Micrographia, an abnormal reduction in script size, may be observed in PD.

Methods: We undertook a systematic review in October 2015 using EMBASE and PubMed with inclusion and exclusion criteria and search terms: Handwriting OR Writing AND Parkinsonism OR Parkinson’s disease. From eligible studies we extracted information relating to participants, experimental tasks and primary analyses. We next started preliminary handwriting analysis in PD and controls. Participants were asked to copy a standardised sentence three times (“Mary had a little lamb its fleece was white as snow”) on unlined paper using a conventional pen. We focused on decrement in script size, which was measured by calculating the area of letter "a" in the 3rd (W3) and 10th word (W10). (Ling et al. Brain 2012: 135;1141-1153). Progressive reduction in size was represented by a negative slope of the regression line fitted to the letter areas across three consecutive sentences.

Results: 57 articles from EMBASE and 5 additional articles from PubMed were deemed suitable for inclusion in the systematic review. There was great heterogeneity in the methods used to assess handwriting in PD. The average number of total participants was 45.6 (patients and controls). The most common experimental task was use of a repetitive "llll" pattern on a graphic tablet, focusing on stroke parameters such as size, velocity and fluency. In preliminary analysis by our group, we observed a decrement in W10 in 75% of PD patients (28 of 37) compared with 63% of controls (29 of 46). The difference was not statistically significant (p=0.49) but differences were more marked in patients that were off at the time of testing (15/18; 83%). Clear differences in handwriting were observed subjectively, and objective analyses will be prioritised henceforth based on the results of the systematic review (e.g. sentence length, sentence sloping and word spacing).

Conclusions: Micrographia is a well-recognised sign in PD, but there is a lack of consensus about how to analyse it objectively. Preliminary analysis suggests that decrement in letter area alone is inadequate and a combination of objective measurements may prove most useful in future.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/handwriting-in-parkinsons-disease-systematic-review-and-preliminary-study/