How does brain structure change in early Parkinson's disease?

What was the primary objective of the ICICLE-PD study regarding structural brain changes?

To investigate regional cortical thickness and subcortical volumes at baseline and evaluate their longitudinal progression over 18 months in a cohort of newly diagnosed, non-demented patients with Parkinson's disease.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

How were Parkinson's disease patients classified into cognitive subgroups at baseline?

They were classified into Parkinson's disease mild cognitive impairment (PD-MCI) and Parkinson's disease with no cognitive impairment (PD-NC) using the Movement Disorders Society (MDS) diagnostic criteria.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What was the final sample size of healthy controls who completed both baseline and longitudinal MRI sessions?

Out of 50 initially recruited healthy controls, 38 returned and had usable scans at both baseline and follow-up.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What diagnostic standards were used to exclude patients presenting with dementia at the start of the study?

Patients with baseline dementia were excluded based on DSM-IV or MDS criteria for dementia.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Which software suite was used to perform cortical reconstruction and subcortical segmentation?

FreeSurfer (version 5.3) image analysis suite.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

How is cortical thickness calculated at each vertex within FreeSurfer?

It is calculated as the closest distance from the grey/white matter boundary to the grey/CSF boundary.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What difference in regional cortical thickness was found at baseline between PD-NC and healthy controls?

There were no significant differences in regional cortical thickness between the PD-NC group and healthy controls at baseline.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Which cortical regions demonstrated reduced baseline thickness in PD-MCI compared to healthy controls?

The frontal, parietal, occipital, and cingulate cortices, specifically the left supramarginal, bilateral rostral middle frontal, left isthmus cingulate, right posterior cingulate, and right lateral occipital cortices.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Was there any significant difference in baseline cortical thickness between the PD-MCI and PD-NC groups?

No, no significant differences in regional cortical thickness were detected between PD-MCI and PD-NC at baseline.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Where did PD-NC subjects develop significantly more cortical thinning than healthy controls over 18 months?

In the left caudal middle frontal cortex.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Compared to the PD-NC group, where did PD-MCI subjects show greater cortical thinning over 18 months?

In the frontal and temporal cortices, specifically the left caudal middle frontal, right superior frontal, and left superior temporal cortices.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Which areas experienced greater longitudinal cortical thinning in PD-MCI compared to healthy controls?

The left superior frontal cortex, left supramarginal cortex, and right precuneus (predominantly frontal and parietal regions).

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Which left hemisphere subcortical structures were significantly atrophic in PD-MCI compared to PD-NC at baseline?

The left nucleus accumbens and the left hippocampus.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

Which subcortical region showed greater longitudinal atrophy in PD-MCI compared to both healthy controls and PD-NC?

The right hippocampus.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What longitudinal subcortical volume loss was significantly higher in PD-MCI compared only to healthy controls over 18 months?

Atrophy of the left caudate nucleus.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Did subcortical volumes show any significant correlations with cognitive test performance?

No, no significant associations were found between subcortical volumes and cognitive measures at baseline or follow-up.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Which global cognitive screening score showed a positive association with baseline frontal and temporo-parietal cortical thickness?

The Montreal Cognitive Assessment (MoCA) score.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

How did longitudinal global cognitive decline (measured by MMSE) compare across groups?

The decline in MMSE scores was significantly greater in PD-MCI compared to both PD-NC and healthy controls over 18 months.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What structural feature did the baseline MRI analysis reveal about PD-NC patients who converted to PD-MCI during the study?

They exhibited a baseline bilateral pattern of cortical thinning in the temporal regions compared to stable patients, although this did not survive full covariate correction.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What did the authors suggest to explain how PD-NC subjects could show progressive cortical thinning without showing clinical cognitive decline?

Cortical thinning can precede clinical symptoms, and compensatory functional mechanisms might buffer against early cognitive deficits.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What are the two key components of the dual-syndrome hypothesis supported by the study?

It posits that frontostriatal deficits relate to dopaminergic deficits, whereas progression to dementia is associated with posterior cortical changes.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Why is nucleus accumbens atrophy significant in early Parkinson's disease?

It serves as a likely subcortical substrate linking both cognitive impairment and neuropsychiatric symptoms, such as depression.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

What process is caudate nucleus atrophy over 18 months thought to reflect in PD-MCI?

Dopamine deafferentation of frontostriatal circuits originating in the substantia nigra, which indirectly impairs prefrontal executive loops.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

What is the primary scientific advantage of serial imaging over cross-sectional designs in structural MRI studies?

It allows each subject to serve as their own reference point, which reduces the confounding effects of high inter-individual structural variation.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

Which tests from the CANTAB battery were used to evaluate the memory domain?

Pattern Recognition Memory (PRM), Spatial Recognition Memory (SRM), and Paired Associates Learning (PAL).

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Under the modified level 2 criteria used in this study, how was a subject diagnosed as PD-MCI?

They had to show impairment (at least 1.5 standard deviations below normative means) on two tests in one cognitive domain, or on one test in two different domains.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What major limitation of the study's neuropsychological battery affected visuospatial characterization?

Only one representative test was available to assess visuospatial function, rather than the multiple tests recommended for a full level 2 diagnosis.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

Why is the MMSE pentagon copying task considered a valuable clinical predictor in PD studies?

It is associated with future dementia development and correlates with structural changes in the posterior temporo-parietal cortex.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

What counter-intuitive result was observed for MoCA scores at the 18-month follow-up, and how did the authors explain it?

PD subjects showed an improvement in MoCA, which likely reflected dopaminergic medication modulation of executive subtests since patients were tested in their 'ON' state.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

Which demographics were adjusted as nuisance covariates in all GLM imaging analyses?

Age, gender, and education.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What statistical method corrected for multiple comparisons across the cortical thickness maps?

Family-wise error (FWE) cluster-based correction using Monte Carlo simulations with 10,000 iterations.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

How did the researchers control for the effects of antiparkinsonian medication in their imaging analyses?

They calculated the levodopa equivalent daily dose (LEDD) and included it as a covariate in the statistical comparisons.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What histopathological evidence supports the findings of progressive longitudinal hippocampal atrophy in PD-MCI?

Histopathological evidence demonstrates that the hippocampus is a primary target for Lewy body pathology, especially in the CA2 subfield.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI

Why did researchers conduct manual corrections during the FreeSurfer preprocessing phase?

To repair tissue misclassification and white matter errors, while remaining blinded to diagnostic group information.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified

What hemispheric asymmetry did the researchers notice in the longitudinal cortical changes of the PD-NC group?

They observed an asymmetric pattern of cortical thinning primarily in the left hemisphere over 18 months, suggesting structural degeneration may begin unilaterally.

Source: Baseline and longitudinal grey matter changes in newly diagnosed Parkinson's disease: ICICLE-PD study · DOI · quote verified