Grammatical complexity and productivity in written text in presymptomatic frontotemporal dementia: A repeated measures study.

PURPOSE To assess if the writing performance of presymptomatic frontotemporal dementia mutation carriers differ from that of non-carrier controls in syntactic complexity and productivity.

METHOD Using an automated analysis pipeline, average dependency distance and word count were calculated from written picture descriptions and sentences of 42 cohort participants from The Genetic Frontotemporal Dementia Initiative across three timepoints. Linear mixed models compared several fixed effects including mutation status with text measures over time.

RESULT Genetic status had a positive effect on the number of words in a written picture description, with the presymptomatic mutation carriers producing more words than the non-carrier controls. A significant interaction between genetic status and age was also observed. No effect was found for the models using average dependency distance as the dependent variable.

CONCLUSION We found limited evidence for differences in the written language between mutation carriers and non-carrier controls. As previous studies suggest, cognitive changes in genetic frontotemporal dementia manifest nearer to symptom onset and our participants were on average 11.8 years from expected onset, the anticipated changes might be undetectable at this stage.