Movement Disorder: Parkinson's patients have different types of mild cognitive impairment and different functional network characteristics

Mild cognitive impairment (MCI) is common and heterogeneous in Parkinson's disease (PD)
.

Using a data-driven approach, Williams-Gray and colleagues3 report two distinct cognitive syndromes in Parkinson's disease: (1) the anterior striatum, characterized by deficits in attention and executive function, and Dopaminergic dysfunction, in part due to loss of substantia nigra neurons;

(2) The posterior cortex, characterized by deficits in visuospatial, memory, and language functions, is associated with non-dopaminergic dysfunction and cortical Lewy bodies
.

Interestingly, the posterior cortical subtype (PD-PC) was associated with a higher risk of early Parkinson's disease dementia (PDD), whereas the anterior striatal subtype was not

A meta-analysis reported that compared with cognitively normal PD patients (PD-NCs) and/or healthy controls (HCs), PD-MCI and PDD patients were significantly associated with default mode, frontal, auditory and sensorimotor networks.
Decreased FC in relevant brain regions
.

Compared with cognitively normal PD patients (PD-NC) and/or healthy controls (HCs), PD-MCI and PDD patients had reduced FC in brain regions associated with default mode, frontal lobe, auditory and sensorimotor networks
.

However, only two resting-state FC studies considered heterogeneity in PD-MCI and found FC alterations in default mode, frontal, dorsal attention, and visual networks, in both amnestic and nonamnestic subtypes
.

Regarding the dual syndrome hypothesis, Lang and colleagues reported decreased FC in sensorimotor networks associated with executive difficulty factors, whereas posterior cortical factors were associated with decreased FC in frontal networks and increased FC in temporal limb networks

However, in this study, although PD patients had lower cognitive performance than HCs, it was not stated whether they met the criteria for PD-MCI
.

Furthermore, only intra-network connectivity was investigated, whereas inter-network connectivity dysfunction has been found in PD and PD-MCI

Hereby, Quentin Devignes et al.
, University of Lille, France, identified changes in intra- and inter-network connectivity associated with each cognitive subtype defined in the dual syndrome hypothesis in the PD-MCI population
.

The hypothesis was that PD-MCI patients would show intra- and inter-network FC changes in their cognitive subtype-specific resting-state networks compared to HCs and PD-NCs
.

More specifically, FC changes in networks including patients with frontal and striatal subtypes are expected to be included, whereas FC changes in networks in PD-PC patients, including posterior regions

They divided 95 non-demented patients into normal cognitive (n = 31), anterior striatum (n = 14), posterior cortical (n = 20), or mixed (n = 30) cognitive subtypes, and conducted 3T resting-state fMRI scan
.

Twenty-four age-matched healthy controls (HCs) were also included

They found that functional connectivity (FC) within the basal ganglia network was increased in patients with posterior cortical deficits compared with patients with anterior striatal deficits
.

Functional connectivity (FC) within the basal ganglia network was increased in patients with posterior cortical deficits compared with patients with anterior striatal deficits
.

Compared with HCs, cognitively normal patients, and patients with the posterior cortical subtype, patients with prestriatal deficits had reduced network functional connectivity between several networks, including visual, default mode, sensorimotor, salience, Dorsal attention, basal ganglia, and frontal networks
.

Similar results were found between patients with mixed subtypes and HCs
.

The significance of this study lies in the discovery that: MCI subtypes are associated with specific changes in resting-state FC
.

Longitudinal studies are needed to determine the predictive potential of these markers for dementia risk

MCI subtypes are associated with specific changes in resting-state FC

 

Original source:
Devignes Q, Bordier C, Viard R, et al.

Resting‐State Functional Connectivity in Frontostriatal and Posterior Cortical Subtypes in Parkinson's Disease‐Mild Cognitive Impairment.
Movement Disorders.
Published online December 17, 2021:mds.
28888.
doi: 10.
1002/mds.
28888.

 

leave a message here