Dataset Information

Cortical asymmetry in Parkinson's disease: early susceptibility of the left hemisphere.

ABSTRACT:

Background and purpose

Clinically, Parkinson's disease (PD) presents with asymmetric motor symptoms. The left nigrostriatal system appears more susceptible to early degeneration than the right, and a left-lateralized pattern of early neuropathological changes is also described in several neurodegenerative conditions, including Alzheimer's disease, frontotemporal dementia, and Huntington's disease. In this study, we evaluated hemispheric differences in estimated rates of atrophy in a large, well-characterized cohort of PD patients.

Methods

Our cohort included 205 PD patients who underwent clinical assessments and T1-weighted brain MRI's. Patients were classified into Early (n = 109) and Late stage (n = 96) based on disease duration, defined as greater than or less than 10 years of motor symptoms. Cortical thickness was determined using FreeSurfer, and a bootstrapped linear regression model was used to estimate differences in rates of atrophy between Early and Late patients.

Results

Our results show that patients classified as Early stage exhibit a greater estimated rate of cortical atrophy in left frontal regions, especially the left insula and olfactory sulcus. This pattern was replicated in left-handed patients, and was not influenced by the degree of motor symptom asymmetry (i.e., left-sided predominant motor symptoms). Patients classified as Late stage exhibited greater atrophy in the bilateral occipital, and right hemisphere-predominant cortical areas.

Conclusions

We show that cortical degeneration in PD differs between cerebral hemispheres, and findings suggest a pattern of early left, and late right hemisphere with posterior cortical atrophy. Further investigation is warranted to elucidate the underlying mechanisms of this asymmetry and pathologic implications.

SUBMITTER: Claassen DO

PROVIDER: S-EPMC5167000 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Publications

Cortical asymmetry in Parkinson's disease: early susceptibility of the left hemisphere.

Claassen Daniel O DO McDonell Katherine E KE Donahue Manus M Rawal Shiv S Wylie Scott A SA Neimat Joseph S JS Kang Hakmook H Hedera Peter P Zald David D Landman Bennett B Dawant Benoit B Rane Swati S

Brain and behavior 20161006 12

<h4>Background and purpose</h4>Clinically, Parkinson's disease (PD) presents with asymmetric motor symptoms. The left nigrostriatal system appears more susceptible to early degeneration than the right, and a left-lateralized pattern of early neuropathological changes is also described in several neurodegenerative conditions, including Alzheimer's disease, frontotemporal dementia, and Huntington's disease. In this study, we evaluated hemispheric differences in estimated rates of atrophy in a larg ...[more]

PMID: 28031997

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Project description:Asymmetric dopaminergic degeneration of the striatum is a characteristic feature of Parkinson's disease, associated with right-left asymmetry in motor function. As such, studying asymmetry provides insights into progressive neurodegeneration between cerebral hemispheres. Given the impact of Lewy pathology on various neurotransmitter systems beyond the dopaminergic, it may be that other neuronal systems in the predominantly affected hemisphere are similarly affected. According to this hypothesis, asymmetry in dopaminergic degeneration would be expected to coincide with asymmetry in other neurotransmitter systems. Consequently, asymmetry in functions primarily dependent on dopaminergic integrity, such as motor function, should correlate with asymmetry in bilateral non-motor functions that rely on other cerebral systems, such as pupillary function. Therefore, this study tested whether right-left asymmetry in bilateral non-motor measures correlates with asymmetry in dopaminergic striatal integrity. We also tested whether asymmetric striatal degeneration is associated with greater asymmetry in non-motor measures overall. Using a comparative cross-sectional design, we recruited newly diagnosed patients with Parkinson's disease with predominantly right-sided (n = 18), left-sided (n = 15) or symmetric nigrostriatal denervation (n = 15) assessed on dopamine PET. Detailed examinations of lateralized non-motor function included lacrimation, hand skin wrinkling, salivation, olfaction and pupillary function. Healthy controls were recruited for comparison. We observed a moderate-to-strong correlation between right-left asymmetry of putamen dopamine binding and asymmetry in pupillary redilation speed [Spearman's rank correlation coefficient (rs ) = -0.53, 95% confidence interval (-0.77; -0.14), P = 0.0084]. We also observed moderate correlations between non-negative putaminal asymmetry and lacrimation [rs = 0.35, (-0.00; 0.62), P = 0.0464] and word recognition [rs = 0.36, (0.01; 0.63), P = 0.0410]. However, none were significant after false discovery rate correction. We observed significant group differences in non-negative asymmetry in salivation (P = 0.0390, ANOVA) and a trend towards greater asymmetric lacrimation in participants with asymmetric striatal dopamine loss compared with healthy controls (P = 0.0330, unadjusted). Additionally, participants with asymmetric striatal dopaminergic binding showed greater, though non-significant, asymmetry in all pupillary measures compared with those with symmetric dopaminergic binding. In conclusion, this study contributes to our understanding of neurodegeneration progression in Parkinson's disease and suggests a link between dopaminergic degeneration and non-motor measures related to autonomic function, particularly salivation, lacrimation and pupillary function. While our findings do not support a strict right-left hemispheric association between non-motor functions and dopaminergic degeneration, potential relationships may exist between these features and asymmetrical degeneration in other neuronal systems, such as the cholinergic.

Dataset Information

Cortical asymmetry in Parkinson's disease: early susceptibility of the left hemisphere.

Background and purpose

Methods

Results

Conclusions

Publications

Cortical asymmetry in Parkinson's disease: early susceptibility of the left hemisphere.

Similar Datasets

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