Does brain region loss predict memory decline in Parkinson's?

What percentage of patients with Parkinson’s disease will eventually develop dementia during their illness?

Approximately 80% of patients with Parkinson's disease will eventually develop dementia.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What is the primary source of cholinergic innervation to the cerebral cortex that contains Lewy bodies in Parkinson's disease?

The nucleus basalis of Meynert (Ch4).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What was the primary hypothesis of this study regarding the nucleus basalis of Meynert in Parkinson's disease?

Structural and microstructural changes in the nucleus basalis of Meynert and associated limbic pathways underlie and predict cognitive decline.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What database was used to obtain patient data for this study?

The Parkinson’s Progression Markers Initiative (PPMI) database.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Which patients were excluded from the study population during selection?

Subjects with a history of stroke or transient ischaemic attack (TIA).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How was the Level 1 diagnosis of cognitive status determined at baseline?

Based on Montreal Cognitive Assessment (MoCA) scores, with a score of 25 or below indicating impairment.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What three factors defined a Level 2 diagnosis of cognitive impairment at follow-up?

A MoCA score of 25 or lower, self-reported cognitive issues, and at least two cognitive test scores greater than 1.5 SD below healthy control means.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Did baseline cross-sectional comparisons of grey matter reveal differences between healthy controls and Parkinson's patients as a whole?

No, there were no significant regional differences in grey matter, mean diffusivity, or fractional anisotropy between healthy controls and all Parkinson's patients at baseline.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What brain region served as the reference region in this study, and why?

The primary somatosensory cortex area 3a, because it is relatively unaffected by Parkinson's disease and dementia pathology.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Which brain structures showed increased mean diffusivity (MD) in cognitively impaired PD patients compared to cognitively normal PD patients at baseline?

The nucleus basalis of Meynert, entorhinal cortex, insula, and thalamus.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Which region's grey matter volume was the only statistically significant predictor of developing cognitive impairment in multivariate Cox survival analysis when adjusting for age?

The nucleus basalis of Meynert (NBM).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

By how much does the hazard ratio for developing cognitive impairment increase per every 0.01 decrease in NBM grey matter mean voxel value?

The hazard ratio increases by 9.3%.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

By how much does the hazard ratio for developing cognitive impairment increase for every 0.001 increase in NBM DTI mean diffusivity?

It increases by a factor of 11.4.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

When both grey matter volume and mean diffusivity of the NBM are included in the same Cox model, which one remains a significant predictor?

Mean diffusivity (MD) remains the only significant predictor, suggesting microstructural changes precede macroscopic structural loss.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Why did white matter lesions lose their predictive power for cognitive impairment when age was included as a covariate?

The association was driven by the ageing process itself rather than white matter lesions specifically.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI

What happens to the predictive power of axial gait score when evaluated alongside NBM grey matter in a full prognostic model?

It loses its statistical power of prediction.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Why might previous studies have found an association between gait dysfunction and cognitive decline?

Degeneration of cholinergic pathways may concurrently affect the pedunculopontine nucleus (associated with gait) and the nucleus basalis of Meynert (associated with cognition).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What microstructural and structural mismatch was observed in the entorhinal cortex of cognitively impaired patients at baseline?

They had increased mean diffusivity but normal grey matter volume, suggesting microstructural changes precede structural atrophy.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Which two non-imaging markers remained significant predictors of cognitive impairment in the fully adjusted model alongside NBM grey matter?

Olfactory function (UPSIT) and the amyloid-beta:tau ratio in CSF.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What was the medication status of the Parkinson's disease patients at the time of their baseline MRI?

They were drug-naïve (not on Parkinson’s medications).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How were the regions of interest (ROIs) for the nucleus basalis of Meynert and other structures defined in this study?

By using existing probabilistic anatomical maps from the SPM 12 Anatomy Toolbox.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Which cholinergic cell group in the basal forebrain corresponds to the nucleus basalis of Meynert?

The Ch4 cell group.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How did the authors rule out the potentially confounding effects of different MRI scanners and protocols?

They tested for differences in grey matter and mean diffusivity values across manufacturers, field strengths, gating protocols, and imaging centers, finding no significant differences.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What thresholding approach was used to reduce DTI partial volume artifacts caused by brain atrophy?

ROIs were extracted only from regions with more than a 90% probability of containing brain tissue.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What major study limitation did the authors note regarding the clinical classification of cognitive impairment?

The difficulty in distinguishing whether the cognitive impairment is a prodromal form of Parkinson's disease dementia versus another form of dementia (e.g., dementia with Lewy bodies).

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What is the main clinical utility proposed for using NBM degeneration as an MRI biomarker?

It offers a non-invasive, cost-effective way to identify and stratify early-stage Parkinson's patients at high risk of cognitive decline for clinical trials and targeted care.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Did baseline Fractional Anisotropy (FA) within the regions of interest predict longitudinal cognitive decline in the Cox models?

No, none of the FA regions of interest were statistically significant predictors of developing cognitive impairment.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How does the timing of cholinergic neuron degeneration in the basal forebrain compare to dopamine neuron degeneration in the substantia nigra?

Pathological models suggest that cholinergic degeneration in the basal forebrain occurs at the same stage as dopaminergic nigral pathology.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Why was a highly sensitive screening tool (MoCA) beneficial at baseline for the longitudinal study design?

It allowed the researchers to exclude patients with early detectable cognitive impairment, ensuring predictors were identified prior to clinical onset.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Did the predictive value of NBM grey matter volume survive after applying partial volume correction?

Yes, NBM grey matter remained a statistically significant predictor of cognitive impairment even after partial volume correction.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What was the total duration of the longitudinal follow-up for cognitive decline in the Parkinson's cohort?

36 months, with evaluations occurring every 6 months.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

What software suite was used to calculate white matter lesion volumes from T1-weighted images?

The Freesurfer image analysis suite.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How many post-mortem brains were analyzed histologically to construct the probabilistic anatomical maps used in the study?

10 brains.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

How did the authors ensure the stability of the cognitive impairment diagnoses at follow-up?

They confirmed that the cognitive impairment outcome was still present at the subsequent visits.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified

Besides the NBM, which subcortical region showed a significant reduction in grey matter volume in cognitively impaired versus cognitively normal PD patients at baseline after partial volume correction?

The thalamus.

Source: Nucleus basalis of Meynert degeneration precedes and predicts cognitive impairment in Parkinson's disease · DOI · quote verified