Neuroimaging and fluid biomarkers in Parkinson's disease in an era of targeted interventions.

A major challenge in Parkinson's disease is the variability in symptoms and rates of progression, underpinned by heterogeneity of pathological processes. Biomarkers are urgently needed for accurate diagnosis, patient stratification, monitoring disease progression and precise treatment. These were previously lacking, but recently, novel imaging and fluid biomarkers have been developed.

Longitudinal Associations of Magnetic Susceptibility with Clinical Severity in Parkinson's Disease.

Background: Dementia is common in Parkinson's disease (PD), but there is wide variation in its timing. A critical gap in PD research is the lack of quantifiable markers of progression, and methods to identify early stages of dementia. Atrophy-based magnetic resonance imaging (MRI) has limited sensitivity in detecting or tracking changes relating to PD dementia, but quantitative susceptibility mapping (QSM), sensitive to brain tissue iron, shows potential for these purposes.

Structural and Functional Imaging Correlates of Visual Hallucinations in Parkinson's Disease.

Purpose Of Review: To review recent structural and functional MRI studies of visual hallucinations in Parkinson's disease.

Recent Findings: Previously, neuroimaging had shown inconsistent findings in patients with Parkinson's hallucinations, especially in studies examining grey matter volume. However, recent advances in structural and functional MRI techniques allow better estimates of structural connections, as well as the direction of connectivity in functional MRI.

Changes in both top-down and bottom-up effective connectivity drive visual hallucinations in Parkinson's disease.

Visual hallucinations are common in Parkinson's disease and are associated with a poorer quality of life and a higher risk of dementia. An important and influential model that is widely accepted as an explanation for the mechanism of visual hallucinations in Parkinson's disease and other Lewy body diseases is that these arise due to aberrant hierarchical processing, with impaired bottom-up integration of sensory information and overweighting of top-down perceptual priors within the visual system. This hypothesis has been driven by behavioural data and supported indirectly by observations derived from regional activation and correlational measures using neuroimaging.

Sequence of clinical and neurodegeneration events in Parkinson's disease progression.

Dementia is one of the most debilitating aspects of Parkinson's disease. There are no validated biomarkers that can track Parkinson's disease progression, nor accurately identify patients who will develop dementia and when. Understanding the sequence of observable changes in Parkinson's disease in people at elevated risk for developing dementia could provide an integrated biomarker for identifying and managing individuals who will develop Parkinson's dementia.

Brain iron deposition is linked with cognitive severity in Parkinson's disease.

Background: Dementia is common in Parkinson's disease (PD) but measures that track cognitive change in PD are lacking. Brain tissue iron accumulates with age and co-localises with pathological proteins linked to PD dementia such as amyloid. We used quantitative susceptibility mapping (QSM) to detect changes related to cognitive change in PD.

Measuring physiological responses to the arts in people with a dementia.

The dementias are a group of progressive symptoms that have multiple causes, usually caused by disease or injury of the brain, affecting higher brain functions such as language, perception, memory, reasoning and mood; they can also be associated with changes in personality. Arts interventions and interaction with the arts can create meaningful, positive experiences for people with a dementia, as well as improve quality of life. Qualitative research in particular, has been able to describe the emotional responses the arts can produce, but quantifiable changes have not been well documented.