Changes in dynamic transitions between integrated and segregated states underlie visual hallucinations in Parkinson's disease

Hallucinations are a core feature of psychosis and common in Parkinson's. Their transient, unexpected nature suggests a change in dynamic brain states, but underlying causes are unknown. Here, we examine temporal dynamics and underlying structural connectivity in Parkinson's-hallucinations using a combination of functional and structural MRI, network control theory, neurotransmitter density and genetic analyses. We show that Parkinson's-hallucinators spent more time in a predominantly Segregated functional state with fewer between-state transitions. The transition from integrated-to-segregated state had lower energy cost in Parkinson's-hallucinators; and was therefore potentially preferable. The regional energy needed for this transition was correlated with regional neurotransmitter density and gene expression for serotoninergic, GABAergic, noradrenergic and cholinergic, but not dopaminergic, receptors. We show how the combination of neurochemistry and brain structure jointly shape functional brain dynamics leading to hallucinations and highlight potential therapeutic targets by linking these changes to neurotransmitter systems involved in early sensory and complex visual processing.

Serendipity and Observations in Functional Neurosurgery: From James Parkinson's Stroke to Hamani's & Lozano's Flashbacks

BACKGROUND

Serendipity and observations have a noble tradition in medicine, including neurology, and are responsible for many medical treatments (carbamazepine for tic douloureux, amantadine for Parkinson's disease, gabapentin for restless legs…). We aimed at examining the contribution of serendipity and observations to functional neurosurgery. Scholarly publications relevant to the history of functional neurosurgery for movement and psychiatric disorders were reviewed, starting from the pre-stereotactic era. The documents were scrutinized with respect to indications for surgery, surgical methods, and brain targets, in view of determining whether serendipitous discoveries and other observations contributed to various functional neurosurgical procedures.

SUMMARY

James Parkinson's observation that tremors disappeared in the arm of a person with shaking palsy after a hemiparetic stroke encouraged neurosurgeons in the first half of the 20th century to perform ablative procedures on central motor pathways. Following a lobotomy performed by Browder that extended too far medially in a psychiatric patient with coexisting Parkinson's disease (PD), it was noted that the Parkinsonian signs improved. This encouraged Russel Meyers to carry out open surgery on the caudate nucleus and basal ganglia in PD. Cooper introduced ligation of the anterior choroidal artery as a treatment for PD following a surgical accident during a pedunculotomy. Cooper later started to perform stereotactic surgery on the ventrolateral thalamus following the pathological finding that an intended pallidal lesion had in fact targeted the thalamus. Leksell discovered the ideal location of a pallidal lesion being in the posteroventral area empirically, long before the advent of the basal ganglia model of PD. Modern Deep Brain Stimulation (DBS) that started in the thalamus for tremor was the result of an observation by Benabid that intraoperative high-frequency stimulation during a thalamotomy reduced tremor. Both the discoveries of the anterior limbic subthalamic nucleus as a DBS target for OCD and the medial forebrain bundle as a DBS target for depression occurred by chance. Hamani and Lozano observed memory flashbacks in a patient who was undergoing DBS for obesity, which led to the discovery of the fornix as a potential DBS target for Alzheimer's disease.

KEY MESSAGES

In the history of functional neurosurgery, serendipity and observations have resulted in discoveries of several procedures, brain targets for lesioning or DBS as well as new clinical surgical indications. In this era of neuromodulation, this technology should be exquisite in allowing potential serendipitous discoveries, provided that clinicians remain both observant and prepared.

129 Network controllability and regional gene expression explain visual hallucinations in Parkinson’s

Reference

Shine,et al. The role of dysfunctional attentional control networks in visual misperceptions in Parkinson’s disease. HumBrainMapp;2014.

a.zarkali@ucl.ac.uk

Assessment of Risk Factors and Early Presentations of Parkinson Disease in Primary Care in a Diverse UK Population

IMPORTANCE

Early features of Parkinson disease (PD) have been described through population-based studies that overrepresent White, affluent groups and may not be generalizable.

OBJECTIVE

To investigate the association between risk factors and prediagnostic presentations of PD in an ethnically diverse UK population with high socioeconomic deprivation but universal access to health care.

DESIGN, SETTING, AND PARTICIPANTS

A nested case-control study was conducted using electronic health care records on 1 016 277 individuals from primary care practices in East London to extract clinical information recorded between 1990 and February 6, 2018. The data were analyzed between September 3, 2020, and September 3, 2021. Individuals with a diagnosis of PD were compared with controls without PD or other major neurological conditions.

MAIN OUTCOMES AND MEASURES

A matched analysis (10 controls matched for each patient with PD according to age and sex) and an unmatched analysis (adjusted for age and sex) were undertaken using multivariable logistic regression to determine associations between risk factors and prediagnostic presentations to primary care with subsequent diagnosis of PD. Three time periods (<2, 2-<5, and 5-10 years before diagnosis) were analyzed separately and together.

RESULTS

Of 1 016 277 individuals included in the data set, 5699 were excluded and 1055 patients with PD and 1 009 523 controls were included in the analysis. Patients with PD were older than controls (mean [SD], 72.9 [11.3] vs 40.3 [15.2] years), and more were male (632 [59.9%] vs 516 862 [51.2%]). In the matched analysis (1055 individuals with PD and 10 550 controls), associations were found for tremor (odds ratio [OR], 145.96; 95% CI, 90.55-235.28) and memory symptoms (OR, 8.60; 95% CI, 5.91-12.49) less than 2 years before the PD diagnosis. The associations were also found up to 10 years before PD diagnosis for tremor and 5 years for memory symptoms. Among midlife risk factors, hypertension (OR, 1.36; 95% CI, 1.19-1.55) and type 2 diabetes (OR, 1.39; 95% CI, 1.19-1.62) were associated with subsequent diagnosis of PD. Associations with early nonmotor features, including hypotension (OR, 6.84; 95% CI, 3.38-13.85), constipation (OR, 3.29; 95% CI, 2.32-4.66), and depression (OR, 4.69; 95% CI, 2.88-7.63), were also noted. Associations were found for epilepsy (OR, 2.5; 95% CI, 1.63-3.83) and hearing loss (OR, 1.66; 95% CI, 1.06-2.58), which have not previously been well reported. These findings were replicated using data from the UK Biobank. No association with future PD diagnosis was found for ethnicity or deprivation index level.

CONCLUSIONS AND RELEVANCE

This study provides data suggesting that a range of comorbidities and symptoms are encountered in primary care settings before PD diagnosis in an ethnically diverse and deprived population. Novel temporal associations were observed for epilepsy and hearing loss with subsequent development of PD. The prominence of memory symptoms suggests an excess of cognitive dysfunction in early PD in this population or difficulty in correctly ascertaining symptoms in traditionally underrepresented groups.

Opicapone Use in Clinical Practice across Germany: A Sub-Analysis of the OPTIPARK Study in Parkinson's Disease Patients with Motor Fluctuations

INTRODUCTION

The OPTIPARK study confirmed the effectiveness and safety of opicapone as adjunct therapy to levodopa in patients with Parkinson's disease (PD) and motor fluctuations under real-world conditions. The aim of this sub-analysis was to evaluate opicapone in the German patient cohort of OPTIPARK in order to provide country-specific data.

METHODS

OPTIPARK was an open-label, single-arm study conducted in routine clinical practice across Germany and the UK. Patients with PD and motor fluctuations received once-daily opicapone 50 mg for 3 months in addition to levodopa. The primary endpoint was Clinicians' Global Impression of Change (CGI-C). Secondary assessments included Patients' Global Impressions of Change (PGI-C), Unified Parkinson's Disease Rating Scale (UPDRS) I-IV, Parkinson's Disease Questionnaire (PDQ-8), and Non-Motor Symptoms Scale (NMSS). This sub-analysis reports outcomes from the German patients only.

RESULTS

Overall, 363 (97.6%) of the 372 patients included in the German cohort received ≥1 dose of opicapone and 291 (80.2%) completed the study. Improvements on CGI-C and PGI-C were reported by 70.8% and 76.3% of patients, respectively. UPDRS scores improved for activities of daily living during OFF time by -3.3 ± 4.5 points and motor scores during ON time by -5.3 ± 7.9 points. PDQ-8 and NMSS scores also demonstrated improvements. Treatment emergent adverse events considered at least possibly related to opicapone occurred in 37.7% of patients, with most being of mild or moderate intensity.

CONCLUSION

Opicapone added to levodopa in patients with PD and motor fluctuations was effective and generally well tolerated in routine clinical practice across Germany.

Charcot's Anglophilia

Jean-Martin Charcot was one of the most influential physicians of the nineteenth century and is now rightly considered the father of Neurology. The aim of this paper was to review and describe Charcot's close relationships to Britain and the influence of this particular affinity on his career.

Neuropsychiatric Features of Punding and Hobbyism in Parkinson's Disease

BACKGROUND

Little is known about the cognitive and neuropsychiatric profile associated with punding and hobbyism in Parkinson's disease (PD).

OBJECTIVE

To compare the clinical and neuropsychological features of PD patients with punding and hobbyism to PD controls.

METHODS

The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) was used as a screening tool, and a structured interview was used to diagnose punding/hobbyism. Clinical and neuropsychological assessment was conducted with validated questionnaires/scales.

RESULTS

Twenty-one patients with PD and punding (PD + pu) were compared to 26 with hobbyism (PD + h) and 25 PD controls. PD + pu patients showed higher levels of anxiety, non-motor symptoms and motor symptoms, and lower Frontal Assessment Battery scores. The PD + h group exhibited similar levels of anxiety and motor fluctuations to the PD + pu group.

CONCLUSION

PD + pu showed increased anxiety and frontal lobe dysfunction, similar to PD + h. Hobbyism could be a prodromal phase with increased risk of leading to punding.

Reply to 'Impulse control disorders are associated with lower ventral striatum dopamine D3 receptor availability in Parkinson's disease: A [11C]-PHNO PET study.'

Pagano and collaborators have recently reported lower ventral striatum D3 receptor availability in Parkinson's disease using PET scan. Our group conducted the first postmortem study of individuals with PD who had ICD and related behaviours in life and reported lower alpha-synuclein pathology and D3R levels in the nucleus accumbens of such individuals. The findings by Pagano and co-authors of low D3R binding in PD patients at baseline, when taken together with our findings of lower Lewy pathology and D3R in the nucleus accumbens, favour the hypothesis that D3R levels are downregulated because of excessive synaptic dopamine.

Optimising classification of Parkinson's disease based on motor, olfactory, neuropsychiatric and sleep features

Olfactory loss, motor impairment, anxiety/depression, and REM-sleep behaviour disorder (RBD) are prodromal Parkinson’s disease (PD) features. PD risk prediction models typically dichotomize test results and apply likelihood ratios (LRs) to scores above and below cut-offs. We investigate whether LRs for specific test values could enhance classification between PD and controls. PD patient data on smell (UPSIT), possible RBD (RBD Screening Questionnaire), and anxiety/depression (LADS) were taken from the Tracking Parkinson’s study (n = 1046). For motor impairment (BRAIN test) in PD cases, published data were supplemented (n = 87). Control data (HADS for anxiety/depression) were taken from the PREDICT-PD pilot study (n = 1314). UPSIT, RBDSQ, and anxiety/depression data were analysed using logistic regression to determine which items were associated with PD. Gaussian distributions were fitted to BRAIN test scores. LRs were calculated from logistic regression models or score distributions. False-positive rates (FPRs) for specified detection rates (DRs) were calculated. Sixteen odours were associated with PD; LRs for this set ranged from 0.005 to 5511. Six RBDSQ and seven anxiety/depression questions were associated with PD; LRs ranged from 0.35 to 69 and from 0.002 to 402, respectively. BRAIN test LRs ranged from 0.16 to 1311. For a 70% DR, the FPR was 2.4% for the 16 odours, 4.6% for anxiety/depression, 16.0% for the BRAIN test, and 20.0% for the RBDSQ. Specific selections of (prodromal) PD marker features rather than dichotomized marker test results optimize PD classification. Such optimized classification models could improve the ability of algorithms to detect prodromal PD; however, prospective studies are needed to investigate their value for PD-prediction models.

Regional brain iron and gene expression provide insights into neurodegeneration in Parkinson's disease

The mechanisms responsible for the selective vulnerability of specific neuronal populations in Parkinson's disease are poorly understood. Oxidative stress secondary to brain iron accumulation is one postulated mechanism. We measured iron deposition in 180 cortical regions of 96 patients with Parkinson's disease and 35 control subjects using quantitative susceptibility mapping. We estimated the expression of 15 745 genes in the same regions using transcriptomic data from the Allen Human Brain Atlas. Using partial least squares regression, we then identified the profile of gene transcription in the healthy brain that underlies increased cortical iron in patients with Parkinson's disease relative to controls. Applying gene ontological tools, we investigated the biological processes and cell types associated with this transcriptomic profile and identified the sets of genes with spatial expression profiles in control brains that correlated significantly with the spatial pattern of cortical iron deposition in Parkinson's disease. Gene ontological analyses revealed that these genes were enriched for biological processes relating to heavy metal detoxification, synaptic function and nervous system development and were predominantly expressed in astrocytes and glutamatergic neurons. Furthermore, we demonstrated that the genes differentially expressed in Parkinson's disease are associated with the pattern of cortical expression identified in this study. Our findings provide mechanistic insights into regional selective vulnerabilities in Parkinson's disease, particularly the processes involving iron accumulation.

Slow Motion Analysis of Repetitive Tapping (SMART) Test: Measuring Bradykinesia in Recently Diagnosed Parkinson's Disease and Idiopathic Anosmia

BACKGROUND

Bradykinesia is the defining motor feature of Parkinson's disease (PD). There are limitations to its assessment using standard clinical rating scales, especially in the early stages of PD when a floor effect may be observed.

OBJECTIVE

To develop a quantitative method to track repetitive tapping movements and to compare people in the early stages of PD, healthy controls, and individuals with idiopathic anosmia.

METHODS

This was a cross-sectional study of 99 participants (early-stage PD = 26, controls = 64, idiopathic anosmia = 9). For each participant, repetitive finger tapping was recorded over 20 seconds using a smartphone at 240 frames per second. From each video, amplitude between fingers, frequency (number of taps per second), and velocity (distance travelled per second) was extracted. Clinical assessment was based on the motor section of the MDS-UPDRS.

RESULTS

People in the early stage of PD performed the task with slower velocity (p <  0.001) and with greater frequency slope than controls (p = 0.003). The combination of reduced velocity and greater frequency slope obtained the best accuracy to separate early-stage PD from controls based on metric thresholds alone (AUC = 0.88). Individuals with anosmia exhibited slower velocity (p = 0.001) and smaller amplitude (p <  0.001) compared with controls.

CONCLUSION

We present a simple, proof-of-concept method to detect early motor dysfunction in PD. Mean tap velocity appeared to be the best parameter to differentiate patients with PD from controls. Patients with anosmia also showed detectable differences in motor performance compared with controls which may suggest that some were in the prodromal phase of PD.

Visual hallucinations

Visual hallucinations have intrigued neurologists and physicians for generations due to patients' vivid and fascinating descriptions. They are most commonly associated with Parkinson's disease and dementia with Lewy bodies, but also occur in people with visual loss, where they are known as Charles Bonnet syndrome. More rarely, they can develop in other neurological conditions, such as thalamic or midbrain lesions, when they are known as peduncular hallucinosis. This review considers the mechanisms underlying visual hallucinations across diagnoses, including visual loss, network dysfunction across the brain and changes in neurotransmitters. We propose a framework to explain why visual hallucinations occur most commonly in Parkinson's disease and dementia with Lewy bodies, and discuss treatment approaches to visual hallucinations in these conditions.

Identification of multiple system atrophy mimicking Parkinson's disease or progressive supranuclear palsy

We studied a subset of patients with autopsy-confirmed multiple system atrophy who presented a clinical picture that closely resembled either Parkinson's disease or progressive supranuclear palsy. These mimics are not captured by the current diagnostic criteria for multiple system atrophy. Among 218 autopsy-proven multiple system atrophy cases reviewed, 177 (81.2%) were clinically diagnosed and pathologically confirmed as multiple system atrophy (i.e. typical cases), while the remaining 41 (18.8%) had received an alternative clinical diagnosis, including Parkinson's disease (i.e. Parkinson's disease mimics; n = 16) and progressive supranuclear palsy (i.e. progressive supranuclear palsy mimics; n = 17). We also reviewed the clinical records of another 105 patients with pathologically confirmed Parkinson's disease or progressive supranuclear palsy, who had received a correct final clinical diagnosis (i.e. Parkinson's disease, n = 35; progressive supranuclear palsy-Richardson syndrome, n = 35; and progressive supranuclear palsy-parkinsonism, n = 35). We investigated 12 red flag features that would support a diagnosis of multiple system atrophy according to the current diagnostic criteria. Compared with typical multiple system atrophy, Parkinson's disease mimics more frequently had a good levodopa response and visual hallucinations. Vertical gaze palsy and apraxia of eyelid opening were more commonly observed in progressive supranuclear palsy mimics. Multiple logistic regression analysis revealed an increased likelihood of having multiple system atrophy [Parkinson's disease mimic versus typical Parkinson's disease, odds ratio (OR): 8.1; progressive supranuclear palsy mimic versus typical progressive supranuclear palsy, OR: 2.3] if a patient developed any one of seven selected red flag features in the first 10 years of disease. Severe autonomic dysfunction (orthostatic hypotension and/or urinary incontinence with the need for a urinary catheter) was more frequent in clinically atypical multiple system atrophy than other parkinsonian disorders (Parkinson's disease mimic versus typical Parkinson's disease, OR: 4.1; progressive supranuclear palsy mimic versus typical progressive supranuclear palsy, OR: 8.8). The atypical multiple system atrophy cases more frequently had autonomic dysfunction within 3 years of symptom onset than the pathologically confirmed patients with Parkinson's disease or progressive supranuclear palsy (Parkinson's disease mimic versus typical Parkinson's disease, OR: 4.7; progressive supranuclear palsy mimic versus typical progressive supranuclear palsy, OR: 2.7). Using all included clinical features and 21 early clinical features within 3 years of symptom onset, we developed decision tree algorithms with combinations of clinical pointers to differentiate clinically atypical cases of multiple system atrophy from Parkinson's disease or progressive supranuclear palsy.

Visual Dysfunction Predicts Cognitive Impairment and White Matter Degeneration in Parkinson's Disease

BACKGROUND

Visual dysfunction predicts dementia in Parkinson's disease (PD), but whether this translates to structural change is not known. The objectives of this study were to identify longitudinal white matter changes in patients with Parkinson's disease and low visual function and also in those who developed mild cognitive impairment.

METHODS

We used fixel-based analysis to examine longitudinal white matter change in PD. Diffusion MRI and clinical assessments were performed in 77 patients at baseline (22 low visual function/55 intact vision and 13 PD-mild cognitive impairment/51 normal cognition) and 25 controls and again after 18 months. We compared microstructural changes in fiber density, macrostructural changes in fiber bundle cross-section and combined fiber density and cross-section, across white matter, adjusting for age, sex, and intracranial volume.

RESULTS

Patients with PD and visual dysfunction showed worse cognitive performance at follow-up and were more likely to develop mild cognitive impairment compared with those with normal vision (P = 0.008). Parkinson's with poor visual function showed diffuse microstructural and macrostructural changes at baseline, whereas those with mild cognitive impairment showed fewer baseline changes. At follow-up, Parkinson's with low visual function showed widespread macrostructural changes, involving the fronto-occipital fasciculi, external capsules, and middle cerebellar peduncles bilaterally. No longitudinal change was seen in those with mild cognitive impairment at baseline or converters, even when the 2 groups were combined.

CONCLUSION

Parkinson's patients with poor visual function show increased white matter damage over time, providing further evidence for visual function as a marker of imminent cognitive decline. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Bird watching on the asphalt

Attempting to make a diagnosis from a collection of baffling symptoms is comparable to the challenge of identifying an unusual bird that refuses to stay still. Andrew Lees describes how bird watching and a love of natural history helped turn him not only into a noticer, but ultimately into a neurologist.

Ethnic Variation in the Manifestation of Parkinson's Disease: A Narrative Review

The global prevalence of Parkinson's disease is increasing, yet the characteristics, risk factors and genetics of PD in Black, Asian and Hispanic populations is little understood. In this paper we review the published literature on clinical variation in the symptoms and signs of Parkinson's disease in different ethnic groups and responses to treatment. We included any study that sampled patients with Parkinson's disease from distinct ethnic backgrounds. We conclude that whilst there is little published evidence for ethnic variation in the clinical features of Parkinson's disease, there are substantial limitations and gaps in the current literature, which mean that the evidence does necessarily not fit with clinical observation. Possible explanations for expected differences in manifestation include genetic determinants, the co-existence of cerebrovascular disease and/or Alzheimer's disease pathology, healthcare inequalities and socio-cultural factors.

Improving estimation of Parkinson's disease risk-the enhanced PREDICT-PD algorithm

We previously reported a basic algorithm to identify the risk of Parkinson’s disease (PD) using published data on risk factors and prodromal features. Using this algorithm, the PREDICT-PD study identified individuals at increased risk of PD and used tapping speed, hyposmia and REM sleep behaviour disorder (RBD) as “intermediate” markers of prodromal PD in the absence of sufficient incident cases. We have now developed and tested an enhanced algorithm which incorporates the intermediate markers into the risk model. Risk estimates were compared using the enhanced and the basic algorithm in members of the PREDICT-PD pilot cohort. The enhanced PREDICT-PD algorithm yielded a much greater range of risk estimates than the basic algorithm (93–609-fold difference between the 10th and 90th centiles vs 10–13-fold respectively). There was a greater increase in the risk of PD with increasing risk scores for the enhanced algorithm than for the basic algorithm (hazard ratios per one standard deviation increase in log risk of 2.75 [95% CI 1.68–4.50; p < 0.001] versus 1.47 [95% CI 0.86–2.51; p = 0.16] respectively). Estimates from the enhanced algorithm also correlated more closely with subclinical striatal DaT-SPECT dopamine depletion (R² = 0.164, p = 0.005 vs R² = 0.043, p = 0.17). Incorporating the previous intermediate markers of prodromal PD and using likelihood ratios improved the accuracy of the PREDICT-PD prediction algorithm.