Neural substrates underlying distinct dual cognitive syndromes in Parkinson's disease.

Background: A dual-syndrome hypothesis, which states the cognitive impairments in Parkinson's disease (PD) are attributable to frontostriatal dopaminergic dysregulation and cortical disturbance-each associated with attention/executive and memory/visuospatial dysfunction, respectively-has been widely accepted. This multisystem contribution also underlies highly heterogeneous progression rate to dementia.

Methods: Nondemented PD patients who underwent [I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ([I]FP-CIT) SPECT and neuropsychological examinations were enrolled.

Delineating three distinct spatiotemporal patterns of brain atrophy in Parkinson's disease.

The clinical manifestation of Parkinson's disease exhibits significant heterogeneity in the prevalence of non-motor symptoms and the rate of progression of motor symptoms, suggesting that Parkinson's disease can be classified into distinct subtypes. In this study, we aimed to explore this heterogeneity by identifying a set of subtypes with distinct patterns of spatiotemporal trajectories of neurodegeneration. We applied Subtype and Stage Inference (SuStaIn), an unsupervised machine learning algorithm that combined disease progression modelling with clustering methods, to cortical and subcortical neurodegeneration visible on 3 T structural MRI of a large cross-sectional sample of 504 patients and 279 healthy controls.

A pontine-medullary loop crucial for REM sleep and its deficit in Parkinson's disease.

Identifying the properties of the rapid eye movement (REM) sleep circuitry and its relation to diseases has been challenging due to the neuronal heterogeneity of the brainstem. Here, we show in mice that neurons in the pontine sublaterodorsal tegmentum (SubLDT) that express corticotropin-releasing hormone-binding protein (Crhbp neurons) and project to the medulla promote REM sleep. Within the medullary area receiving projections from Crhbp neurons, neurons expressing nitric oxide synthase 1 (Nos1 neurons) project to the SubLDT and promote REM sleep, suggesting a positively interacting loop between the pons and the medulla operating as a core REM sleep circuit.

Involvement of the basal forebrain and hippocampus in memory deficits in Parkinson's disease.

Introduction: Magnetic resonance imaging (MRI)-determined atrophy of the nucleus basalis of Meynert (Ch4) predicts cognitive decline in Parkinson's disease (PD). However, interactions with other brain regions causing the decline remain unclear. This study aimed to describe how MRI-determined Ch4 atrophy leads to cognitive decline in patients with PD.