Impulsivity Relates to Relative Preservation of Mesolimbic Connectivity in Patients with Parkinson Disease

Hiro Sparks; Hannah Riskin-Jones; Collin Price; Jasmine DiCesare; Ausaf Bari; Nadia Hashoush; Nader Pouratian

doi:10.1016/j.nicl.2020.102259

Impulsivity Relates to Relative Preservation of Mesolimbic Connectivity in Patients with Parkinson Disease

Neuroimage Clin. 2020:27:102259. doi: 10.1016/j.nicl.2020.102259. Epub 2020 Apr 22.

Authors

Hiro Sparks¹, Hannah Riskin-Jones¹, Collin Price², Jasmine DiCesare¹, Ausaf Bari¹, Nadia Hashoush¹, Nader Pouratian³

Affiliations

¹ Department of Neurosurgery, 300 UCLA Stein Plaza, Suite 526; David Geffen School of Medicine at UCLA (University of California, Los Angeles, CA, USA.
² Department of Psychiatry, 150 UCLA Medical Plaza Driveway; David Geffen School of Medicine at UCLA (University of California, Los Angeles, CA, USA.
³ Department of Neurosurgery, 300 UCLA Stein Plaza, Suite 526; David Geffen School of Medicine at UCLA (University of California, Los Angeles, CA, USA. Electronic address: npouratian@mednet.ucla.edu.

Abstract

Introduction: The relationship between Parkinson Disease (PD) pathology, dopamine replacement therapy (DRT), and impulse control disorder (ICD) development is still incompletely understood. Given the sensorimotor-lateral substantia nigra (SN) selective degeneration associated with PD, we posit that a relative sparing of the limbic-medial SN in the context of DRT drives impulsive, reward-seeking behavior in PD patients with recent history of severe impulsivity.

Methods: Impulsive and control participants were selected from a consecutive list of PD patients receiving pre-operative deep brain stimulation (DBS) planning scans including 3T structural MRI and 64 direction diffusion tensor imaging (DTI). Using previously identified substantia nigra (SN) subsegment network connectivity profiles to develop classification targets, split-hemisphere target-based SN segmentation with probabilistic tractography was performed. The relative subsegment volumes and strength of connectivity between the SN and the limbic, associative, and motor network targets were compared.

Results: Our results show that there is greater probability of connectivity between the SN and limbic network targets relative to motor and associative network targets in PD patients with recent history of severe impulsivity as compared to PD patients without impulsivity (P = 0.0075). We did not observe relative volumetric subsegment differences across groups.

Conclusion: Firstly, our results suggest that fine-grained, atlas-derived classification targets may be used in PD to parcellate and classify functionally distinct subsegments of the SN, with the apparent preservation of previously reported topographical limbic-medial SN, associative-ventral SN, and sensorimotor-lateral SN orientation. We suggest that relative, as opposed to absolute, degeneration amongst SN-associated dopaminergic networks relates to the impulsivity phenotype in PD.

Keywords: Parkinson Disease; diffusion tensor imaging; impulse control disorder; impulsivity; substantia nigra.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Diffusion Tensor Imaging / methods
Female
Humans
Impulsive Behavior / physiology*
Magnetic Resonance Imaging / methods
Male
Middle Aged
Neural Pathways / physiology
Neural Pathways / physiopathology*
Parkinson Disease / pathology*
Parkinson Disease / physiopathology*
Reward
Substantia Nigra / pathology
Substantia Nigra / physiopathology*

Abstract

Publication types

MeSH terms

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