Objective: This study was designed to clarify the changes of detailed functional connectivity in association with phonemic fluency deficits in Parkinson’s disease (PD) patients using MRI.

Background: Phonemic fluency deficits are commonly described in non-demented Parkinson’s disease patients, but the mechanisms and functional connectivity changes are still unclear.

Methods: We investigated 60 non-demented PD patients. All patients underwent the Addenbrooke’s Cognitive Examination-Revised (ACE-R), which contains a phonemic fluency task. In the examination of the number of phonemic words (given the letter “KA” in Japanese) generated in one minute, 22 out of 60 PD patients who produced a lower number of words than the average–SD number of words in age- and gender-matched healthy control subjects (HC), designated as lower phonemic fluency positive (PD-LPP). Thirty-eight PD patients with normal phonemic fluency were classified as lower phonemic fluency negative (PD-LPN). We enrolled 22 PD-LPP patients as well as 22 out of 38 PD-LPN patients who were matched for age, gender, age of onset, disease duration, motor symptoms, MMSE, ACE-R subscores (attention/orientation, memory, language and visuospatial ability – all except for fluency), and the number of semantic fluency task words (animal naming). We also enrolled 22 age- and gender-matched HC. T1-weighted and resting-state fMRI were obtained with a 3T MRI scanner (Verio, Siemens, Germany).

Results: Volumetry and independent component analysis of 14 well-known resting state networks including the default mode network and the salience network didn’t show significant differences among PD-LPP, PD-LPN, and HC. However, graph-theoretical analyses with 499 ROIs demonstrated that the PD-LPP group had significant reductions in functional connectivity, mainly in the prefrontal-anterior part of temporal-parietotemporal networks, compared with PD-LPN and HC.

Conclusions: Our study indicates that low scores on the phonemic task in PD appears to be associated with disruption of specific functional connectivity regarding phonemic fluency, prior to gray matter atrophy and dysfunction of fundamental resting state networks.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/disruption-of-functional-connectivity-in-parkinsons-disease-patients-presenting-phonemic-fluency-impairment/