Writing errors in primary progressive aphasia

Abstract

Peripheral errors in writing, that is errors produced download the spelling, have been occasionally described in primary progressive aphasia (PPA), but the possibility that these errors might be a marker of parkinsonism associated to some subtypes of PPA has not been explored. We investigated whether errors of peripheral nature characterize the writing disorder in PPA when associated with parkinsonian signs (PSs). Subgroups of PPA without PSs and with PSs were studied. The proportion of the central and peripheral errors in writing words and pseudowords was calculated in each group. In writing words, central errors significantly exceeded peripheral errors in subgroups without PSs. The higher the number of peripheral errors, the higher the probability of presenting PSs. No relation emerged between any error and the Unified Parkinson’s Disease Rating Scale, but both types of errors correlated with measures of cognitive ability. Peripheral errors emerge when PSs are associated with PPA and may be linked to a decay of the cognitive control on movement, possibly involving the right hemisphere. Peripheral errors have clinical relevance in PPA, to the extent that they may assume the significance of a marker of specific subtypes and can help to outline the specific clinical picture of individual patients.

Keywords:

• Parkinsonian signs
• peripheral errors
• precision medicine
• primary progressive aphasia
• writing disorder

Disclosure statement

The authors declare no financial or other conflicts of interest. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Notes

1 In Italian language, word such as “cieco” (blind) and the word “ceco” (Czech) are homophones. Thus, orthography is derived by the context; when writing a single word on dictation, normal subjects are expected to write “cieco” and not “ceco,” given that the frequency of use of the word “cieco” is much higher than for “ceco.” To correctly write words such as “nacquero” [they were born] in the place of “naquero” orthographic knowledge of the word is necessary.