Abstract Details

Title Anatomical Correlates of Verbal Fluency in Parkinson Disease

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 9-002

Objective We aimed to determine whether disruption of the left dorsal and ventral language white matter pathways are related to performance in phonemic and semantic verbal fluency tasks, respectively, in individuals with Parkinson disease.

Background Our understanding of the neurobiology of language is experiencing a paradigm shift. The classic Lichtheim-Wernicke model that confined language function to the peri-Sylvian regions of the dominant hemisphere is now being relegated by a dual-stream network organization. This model describes a dorsal and a ventral network that support phonological and semantic encoding, respectively. Evidence for this model comes mainly from individuals with stroke and healthy, normal individuals. However, whether this applies to individuals with neurodegenerative conditions, particularly Parkinson disease, remains unknown.

Design/Methods We performed a retrospective observational study using individual structural connectomes derived from the Parkinson's progression markers initiative (PPMI) database. Connectivity between gray matter regions of interest constituting the dorsal and ventral streams in the left hemisphere was assessed through white matter tractography in diffusion tensor space, and phonological and semantic encoding performance was derived through letter and category verbal fluency tasks, respectively. We assessed the relationship between white matter pathways and verbal fluency tasks with correlations analyses, corrected for multiple comparisons.

Results Decreased connectivity in portions of the dorsal stream, particularly those connecting to the angular gyrus and posterior superior temporal gyrus, significantly correlated with performance in phonemic fluency tasks. In contrast, connectivity within the posterior temporal portion of the ventral stream correlated significantly with semantic fluency performance.

Conclusions Our results suggest phonemic and semantic fluency performance among individuals with Parkinson disease rely on the integrity of separate pathways. These observations provide initial evidence that the complex speech and language impairments in Parkinson disease are dissociated to distinctly different supporting structures. This mechanistic observation can provide the basis for the development of future treatment interventions.

Authors/Disclosures
Federico J. Rodriguez-Porcel, MD, FAAN (Medical University of South Carolina) PRESENTER	Dr. Rodriguez-Porcel has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BioVie. Dr. Rodriguez-Porcel has received personal compensation in the range of $500-$4,999 for serving as a Consultant for WCG. Dr. Rodriguez-Porcel has received research support from NIH. Dr. Rodriguez-Porcel has received publishing royalties from a publication relating to health care.
	No disclosure on file
Leonardo F. Bonilha, MD (University of South Carolina)	Dr. Bonilha has nothing to disclose.

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