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2 results on '"Myall DJ"'

1. Response to "Parkinson's disease mild cognitive impairment classifications and neurobehavioral symptoms".

Author

Horne KL, Myall DJ, MacAskill MR, Anderson TJ, and Dalrymple-Alford JC

Subjects
Demography, Disease Progression, Humans, Cognitive Dysfunction, Dementia psychology, Parkinson Disease psychology
Abstract

A recent paper, "Parkinson's disease mild cognitive impairment classifications and neurobehavioral symptoms" (McDermott et al., 2017), provides an interesting comparison of the influence of different criteria for Parkinson's disease with mild cognitive impairment (PD-MCI) on progression to dementia (PDD). Unfortunately, McDermott et al. (2017) incorrectly stated that "only 21% of PD-MCI participants (identified with a 1.5 SD cut-off) converted to PDD within four years" (p.6) in our study (Wood et al., 2016). However, the important point made by Wood et al. (2016) was that the proportion of conversions to PDD was 51% when the PD-MCI diagnosis required a minimum of two 1.5 SD impairments within any single cognitive domain, whereas additional PD-MCI patients classified with one impairment at 1.5 SD in each of the two domains (but never two impairments in the same domain) had a non-significant risk of dementia relative to non-MCI patients (11% vs. 6% converted, respectively). Our PDD conversion rate was 38% when combining both 1.5 SD criteria (21/56 PD-MCI patients vs. 4/65 non-MCI patients converted); McDermott et al. (2017) found a 42% conversion rate over three years for similarly described PD-MCI patients (10/24 PD-MCI patients vs. 0/27 non-MCI patients converted). Our study was also part of a multinational study (n = 467) showing that PD-MCI has predictive validity beyond known demographic and PD-specific factors of influence (Hoogland et al., 2017). All three studies found that multiple cognitive domain impairments are common in PD-MCI. Nonetheless, the research community needs to clarify the association between PD-MCI subtypes and, especially, the optimal cognitive markers for dementia risk in PD patients.

Published
2018
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2. Metabolite ratios in the posterior cingulate cortex do not track cognitive decline in Parkinson's disease in a clinical setting.

Author

Almuqbel M, Melzer TR, Myall DJ, MacAskill MR, Pitcher TL, Livingston L, Wood KL, Keenan RJ, Dalrymple-Alford JC, and Anderson TJ

Subjects
Aged, Aged, 80 and over, Aspartic Acid analogs & derivatives, Aspartic Acid metabolism, Bayes Theorem, Case-Control Studies, Choline metabolism, Cognitive Dysfunction psychology, Creatine metabolism, Dementia psychology, Disease Progression, Female, Humans, Inositol metabolism, Magnetic Resonance Spectroscopy, Male, Middle Aged, Neuropsychological Tests, Parkinson Disease psychology, Superior Sagittal Sinus, Cognitive Dysfunction metabolism, Dementia metabolism, Gyrus Cinguli metabolism, Parkinson Disease metabolism
Abstract

Introduction: Parkinson's Disease (PD) is classified as a motor disorder, but most patients develop cognitive impairment, and eventual dementia (PDD). Predictive neurobiomarkers may be useful in the identification of those patients at imminent risk of PDD. Given the compromised cerebral integrity in PDD, we investigated whether brain metabolites track disease progression over time., Methods: Proton Magnetic Resonance Spectroscopy (MRS) was used to identify brain metabolic changes associated with cognitive impairment and dementia in PD. Forty-nine healthy participants and 130 PD patients underwent serial single voxel proton MRS and neuropsychological testing. At baseline patients were classified as either having normal cognitive status (PDN, n = 77), mild cognitive impairment (PDMCI, n = 33), or dementia (PDD, n = 20). Posterior cingulate cortex (PCC) was examined to quantify N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and myo-inositol (mI). A hierarchical Bayesian model was used to assess whether cognitive ability and other covariates were related to baseline MRS values and changes in MRS over time., Results: At baseline, relative to controls, PDD had significantly decreased NAA/Cr and increased Cho/Cr. However, these differences did not remain significant after accounting for age, sex, and MDS-UPDRS III. At follow-up, no significant changes in MRS metabolite ratios were detected, with no relationship found between MRS measures and change in cognitive status., Conclusions: Unlike Alzheimer's disease, single voxel MR spectroscopy of the PCC failed to show any significant association with cognitive status at baseline or over time. This suggests that MRS of PCC is not a clinically useful biomarker for tracking or predicting cognitive impairment in Parkinson's disease., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Published
2016
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