Visual hallucinations, white matter lesions and disease severity in Parkinson's disease

The impact of psychiatric comorbidity on Parkinson's disease outcomes: a systematic review and meta-analysis

Background

The burden of psychiatric symptoms in Parkinson's disease includes depression, anxiety, apathy, psychosis, and impulse control disorders. However, the relationship between psychiatric comorbidities and subsequent prognosis and neurological outcomes is not yet well understood. In this systematic review and meta-analysis, in individuals with Parkinson's disease, we aimed to characterise the association between specific psychiatric comorbidities and subsequent prognosis and neurological outcomes: cognitive impairment, death, disability, disease progression, falls or fractures and care home admission.

Methods

We searched MEDLINE, Embase, PsycINFO and AMED up to 13th November 2023 for longitudinal observational studies which measured disease outcomes in people with Parkinson's disease, with and without specific psychiatric comorbidities, and a minimum of two authors extracted summary data. Studies of individuals with other parkinsonian conditions and those with outcome measures that had high overlap with psychiatric symptoms were excluded to ensure face validity. For each exposure-outcome pair, a random-effects meta-analysis was conducted based on standardised mean difference, using adjusted effect sizes-where available-in preference to unadjusted effect sizes. Study quality was assessed using the Newcastle-Ottawa Scale. Between-study heterogeneity was assessed using the I2 statistic and publication bias was assessed using funnel plots. PROSPERO Study registration number: CRD42022373072.

Findings

There were 55 eligible studies for inclusion in meta-analysis (n = 165,828). Data on participants' sex was available for 164,514, of whom 99,182 (60.3%) were male and 65,460 (39.7%) female. Study quality was mostly high (84%). Significant positive associations were found between psychosis and cognitive impairment (standardised mean difference [SMD] 0.44, [95% confidence interval [CI] 0.23-0.66], I2 30.9), psychosis and disease progression (SMD 0.46, [95% CI 0.12-0.80], I2 70.3%), depression and cognitive impairment (SMD 0.37 [95% CI 0.10-0.65], I2 27.1%), depression and disease progression (SMD 0.46 [95% CI 0.18-0.74], I2 52.2), depression and disability (SMD 0.42 [95% CI 0.25-0.60], I2 7.9%), and apathy and cognitive impairment (SMD 0.60 [95% CI 0.02-1.19], I2 27.9%). Between-study heterogeneity was moderately high.

Interpretation

Psychosis, depression, and apathy in Parkinson's disease are all associated with at least one adverse outcome, including cognitive impairment, disease progression and disability. Whether this relationship is causal is not clear, but the mechanisms underlying these associations require exploration. Clinicians should consider these psychiatric comorbidities to be markers of a poorer prognosis in people with Parkinson's disease. Future studies should investigate the underlying mechanisms and which treatments for these comorbidities may affect Parkinson's disease outcomes.

Funding

Wellcome Trust, UK National Institute for Health Research (NIHR), National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) at South London and Maudsley NHS Foundation Trust and King's College London, National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) at University College London Hospitals NHS Foundation Trust, National Brain Appeal.

White matter hyperintensities and smaller cortical thickness are associated with neuropsychiatric symptoms in neurodegenerative and cerebrovascular diseases

BACKGROUND

Neuropsychiatric symptoms (NPS) are a core feature of most neurodegenerative and cerebrovascular diseases. White matter hyperintensities and brain atrophy have been implicated in NPS. We aimed to investigate the relative contribution of white matter hyperintensities and cortical thickness to NPS in participants across neurodegenerative and cerebrovascular diseases.

METHODS

Five hundred thirteen participants with one of these conditions, i.e. Alzheimer's Disease/Mild Cognitive Impairment, Amyotrophic Lateral Sclerosis, Frontotemporal Dementia, Parkinson's Disease, or Cerebrovascular Disease, were included in the study. NPS were assessed using the Neuropsychiatric Inventory - Questionnaire and grouped into hyperactivity, psychotic, affective, and apathy subsyndromes. White matter hyperintensities were quantified using a semi-automatic segmentation technique and FreeSurfer cortical thickness was used to measure regional grey matter loss.

RESULTS

Although NPS were frequent across the five disease groups, participants with frontotemporal dementia had the highest frequency of hyperactivity, apathy, and affective subsyndromes compared to other groups, whilst psychotic subsyndrome was high in both frontotemporal dementia and Parkinson's disease. Results from univariate and multivariate results showed that various predictors were associated with neuropsychiatric subsyndromes, especially cortical thickness in the inferior frontal, cingulate, and insula regions, sex(female), global cognition, and basal ganglia-thalamus white matter hyperintensities.

CONCLUSIONS

In participants with neurodegenerative and cerebrovascular diseases, our results suggest that smaller cortical thickness and white matter hyperintensity burden in several cortical-subcortical structures may contribute to the development of NPS. Further studies investigating the mechanisms that determine the progression of NPS in various neurodegenerative and cerebrovascular diseases are needed.

Association between white matter lesions and Parkinson's disease: an impact on Postural/Gait difficulty phenotype and cognitive performance

BACKGROUND

White matter hyperintensities (WMHs) may be observed on Magnetic Resonance Imaging (MRI) in patients with Parkinson disease with or without vascular risk factors. Whether WMHs may influence motor and non-motor aspects of Parkinson disease is a subject of debate. The aim of this study is to evaluate the impact of WMH severity on various aspects of Parkinson disease in combination to the estimation of the impact of cerebrovascular risk factors.

MATERIALS AND METHODS

We included a cohort of patients with Parkinson's disease who underwent MRI examination. The Fazekas visual rating scale was used to assess the severity and location of WMHs, and patient clinical characteristics were correlated with MRI data.

RESULTS

All vascular risk factors were associated with higher Fazekas score in both periventricular and deep white matter. Periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs) were associated with lower scores in the ACE-R cognitive assessment scale (p < 0.001). Furthermore, PWMHs and DWMHs severity was associated with higher UPDRS motor score (p < 0.001), while the Postural Instability Gait Difficulty (PIGD) phenotype was correlated with higher burden of WMHs.

CONCLUSIONS

Comorbid WMHs may contribute to multi-dimension dysfunction in patients with Parkinson disease and consequently the management of vascular risk factors may be crucial to maintain motor and non-motor functions in PD.

Optic radiation atrophy in Lewy body disease with visual hallucination on phase difference enhanced magnetic resonance images

Visual hallucinations (VH) occur commonly in Lewy body disease (LBD), including Parkinson's disease (PD), PD with dementia, and dementia with Lewy bodies. We aimed to use phase difference enhanced imaging (PADRE) to assess structural abnormalities of optic radiation (OR) in patients with Lewy body disease (LBD) concomitant with VH. Firstly, two radiologists reviewed the OR appearances in healthy subjects (HS) on PADRE. Next, based on the OR abnormalities, two reviewers assessed the PADRE images from 18 HS and 38 and 110 patients with LBD, with and without VH, respectively, in a blinded manner. Finally, all patients with LBD without VH were eventually followed up for at least 5 years after magnetic resonance imaging to determine the appearance of VH. The radiologists identified three layers, namely external sagittal stratum, internal sagittal stratum, and tapetum, in OR on the PADRE in HS. Moreover, they were able to consensually define the OR as abnormal when the layers were obscured and the disappearance of the cranial side. The sensitivity/specificity of abnormal OR for each case was 68%/81% (LBD with VH vs. LBD without VH). Furthermore, VH appeared in 12 of the 21 (57%) patients with LBD and abnormal OR during the follow-up period. However, no patients without abnormal OR reported VH. Patients with LBD and VH demonstrated the abnormal OR. This, in turn, might be a useful marker to distinguish the patients with VH from those without VH and HS. Moreover, abnormal OR on PADRE may precede the appearance of VH in LBD.

Gray matter, white matter and cerebrospinal fluid abnormalities in Parkinson's disease: A voxel-based morphometry study

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disorder characterized by bradykinesia, tremor, and rigidity among other symptoms. With a 70% cumulative prevalence of dementia in PD, cognitive impairment and neuropsychiatric symptoms are frequent.

MATERIALS AND METHODS

In this study, we looked at anatomical brain differences between groups of patients and controls. A total of 138 people with PD were compared to 64 age-matched healthy people using voxel-based morphometry (VBM). VBM is a fully automated technique that allows for the identification of regional differences in gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) allowing for an objective comparison of brains of different groups of people. We used statistical parametric mapping for image processing and statistical analysis.

RESULTS

In comparison to controls, PD patients had lower GM volumes in the left middle cingulate, left lingual gyrus, right calcarine and left fusiform gyrus, also PD patients indicated lower WM volumes in the right middle cingulate, left lingual gyrus, right calcarine, and left inferior occipital gyrus. Moreover, PD patients group demonstrated higher CSF in the left caudate compared to the controls.

CONCLUSION

Physical fragility and cognitive impairments in PD may be detected more easily if anatomical abnormalities to the cingulate gyrus, occipital lobe and the level of CSF in the caudate are identified. Thus, our findings shed light on the role of the brain in PD and may aid in a better understanding of the events that occur in PD patients.

The psychosis spectrum in Parkinson disease

In 2007, the clinical and research profile of illusions, hallucinations, delusions and related symptoms in Parkinson disease (PD) was raised with the publication of a consensus definition of PD psychosis. Symptoms that were previously deemed benign and clinically insignificant were incorporated into a continuum of severity, leading to the rapid expansion of literature focusing on clinical aspects, mechanisms and treatment. Here, we review this literature and the evolving view of PD psychosis. Key topics include the prospective risk of dementia in individuals with PD psychosis, and the causal and modifying effects of PD medication. We discuss recent developments, including recognition of an increase in the prevalence of psychosis with disease duration, addition of new visual symptoms to the psychosis continuum, and identification of frontal executive, visual perceptual and memory dysfunction at different disease stages. In addition, we highlight novel risk factors - for example, autonomic dysfunction - that have emerged from prospective studies, structural MRI evidence of frontal, parietal, occipital and hippocampal involvement, and approval of pimavanserin for the treatment of PD psychosis. The accumulating evidence raises novel questions and directions for future research to explore the clinical management and biomarker potential of PD psychosis.

Why psychosis is frequently associated with Parkinson's disease?

Psychosis is a common non-motor symptom of Parkinson's disease whose pathogenesis remains poorly understood. Parkinson's disease in conjunction with psychosis has been shown to induce injury to extracorticospinal tracts as well as within some cortical areas. In this study, Parkinson's disease patients with psychosis who did not receive antipsychotic treatment and those without psychosis underwent diffusion tensor imaging. Results revealed that in Parkinson's disease patients with psychosis, damage to the left frontal lobe, bilateral occipital lobe, left cingulated gyrus, and left hippocampal white-matter fibers were greater than damage to the substantia nigra or the globus pallidus. Damage to white-matter fibers in the right frontal lobe and right cingulate gyrus were also more severe than in the globus pallidus, but not the substantia nigra. Damage to frontal lobe and cingulate gyrus white-matter fibers was more apparent than that to occipital or hippocampal fiber damage. Compared with Parkinson's disease patients without psychosis, those with psychosis had significantly lower fractional anisotropy ratios of left frontal lobe, bilateral occipital lobe, left cingu-lated gyrus, and left hippocampus to ipsilateral substantia nigra or globus pallidus, indicating more severe damage to white-matter fibers. These results suggest that psychosis associated with Par-kinson's disease is probably associated with an imbalance in the ratio of white-matter fibers be-tween brain regions associated with psychiatric symptoms (frontal lobe, occipital lobe, cingulate gyrus, and hippocampus) and those associated with the motor symptoms of Parkinson's disease (the substantia nigra and globus pallidus). The relatively greater damage to white-matter fibers in psychiatric symptom-related brain regions than in extracorticospinal tracts might explain why chosis often occurs in Parkinson's disease patients.

Pathophysiology and treatment of psychosis in Parkinson's disease: a review

Psychotic symptoms in Parkinson's disease (PD) are relatively common and, in addition to creating a disturbance in patients' daily lives, have consistently been shown to be associated with poor outcome. Our understanding of the pathophysiology of psychosis in PD has expanded dramatically over the past 15 years, from an initial interpretation of symptoms as dopaminergic drug adverse effects to the current view of a complex interplay of extrinsic and disease-related factors.PD psychosis has unique clinical features, namely that it arises within a context of a clear sensorium and retained insight, there is relative prominence of visual hallucinations and progression occurs over time. PD psychosis tends to emerge later in the disease course, and disease duration represents one risk factor for its development. The use of anti-PD medications (particularly dopamine receptor agonists) has been the most widely identified risk factor for PD psychosis. Other risk factors discussed in the literature include older age, disease severity, sleep disturbance, cognitive impairment, dementia and/or depression.Recent efforts have aimed to explore the complex pathophysiology of PD psychosis, which is now known to involve an interaction between extrinsic, drug-related and intrinsic, disease-related components. The most important extrinsic factor is use of dopaminergic medication, which plays a prominent role in PD psychosis. Intrinsic factors include visual processing deficits (e.g. lower visual acuity, colour and contrast recognition deficits, ocular pathology and functional brain abnormalities identified amongst hallucinating PD patients); sleep dysregulation (e.g. sleep fragmentation and altered dream phenomena); neurochemical (dopamine, serotonin, acetylcholine, etc.) and structural abnormalities involving site-specific Lewy body deposition; and genetics (e.g. apolipoprotein E epsilon4 allele and tau H1H1 genotype). Preliminary reports have also shown a potential relationship between deep brain stimulation surgery and PD psychosis.When reduction in anti-PD medications to the lowest tolerated dose does not improve psychosis, further intervention may be warranted. Several atypical antipsychotic agents (i.e. clozapine, olanzapine) have been shown to be efficacious in reducing psychotic symptoms in PD; however, use of clozapine requires cumbersome monitoring and olanzapine leads to motor worsening. Studies of ziprasidone and aripiprazole are limited to open-label trials and case reports and are highly variable; however, it appears that while each may be effective in some patients, both are associated with adverse effects. While quetiapine has not been determined efficacious in two randomized controlled trials, it is a common first-line treatment for PD psychosis because of its tolerability, ease of use and demonstrated utility in numerous open-label reports. Cholinesterase inhibitors currently represent the most promising pharmacological alternative to antipsychotics. Tacrine is rarely tried because of hepatic toxicity, and controlled trials with donepezil have not shown significant reductions in psychotic symptoms, due perhaps to methodological limitations. However, results from an open-label study and a double-blind, placebo-controlled trial involving 188 hallucinating PD patients support the efficacy of rivastigmine. With regard to non-pharmacological interventions, case reports suggest that electroconvulsive therapy has the potential to reduce psychotic symptoms and may be considered in cases involving concurrent depression and/or medication-refractory psychosis. Limited case reports also suggest that specific antidepressants (i.e. clomipramine and citalopram) may improve psychosis in depressed patients. Finally, studies in the schizophrenia literature indicate that psychological approaches are effective in psychosis management but, to date, this strategy has been supported only qualitatively in PD, and further studies are warranted.

Vascular parkinsonism: clinical correlates predicting motor improvement after lumbar puncture

Vascular parkinsonism (VP) is a poorly defined entity which has clinical, and perhaps pathological, overlap with other diagnoses. Although classical VP involves lesions of the basal ganglia, the majority of cases actually show diffuse subcortical white matter changes (SCWMC) on imaging. The exact pathologies of these white matter changes are debated and likely heterogeneous, but are generally thought to represent areas of chronic or recurrent partial ischemia. Cerebrospinal fluid (CSF) drainage is the treatment for NPH and has been reported to improve symptoms in some patients with idiopathic NPH and associated SCWMC. To determine whether historical, clinical, or radiographic factors predict improvement in VP patients after CSF drainage, we removed 35-40 ml of CSF via lumbar punctures (LP) from 40 patients and compared responders with nonresponders for a variety of demographics, clinical features, and blindly interpreted magnetic resonance images (MRI). Fifteen patients (37.5%) reported "significant and irrefutable" gait improvement after LP. Twelve (30.0%) reported no effect and 13 (32.5%) reported mild or very transient improvement. Timed gait in a subset of patients improved (P < 0.05) immediately after LP. Clinically, improvement after CSF removal was predicted by any positive response to levodopa (P < 0.001), the lack of vertical gaze palsies (P < 0.05), the lack of a pure freezing gait (P < 0.05), and the lack of hypotensive episodes (P < 0.05). Blinded MRI interpretation did not find features which clearly predicted response. Some patients diagnosed with VP improved after LP. Clinically, these patients tended to resemble idiopathic PD, whereas nonresponders more closely resembled progressive supranuclear palsy (PSP). These results warrant further investigation and also raise the possibility of testing CSF drainage in patients with idiopathic PD complicated by SCWMC.

Visual hallucinations in Parkinson's disease: a review and phenomenological survey

OBJECTIVES

Between 8% and 40% of patients with Parkinson's disease undergoing long term treatment will have visual hallucinations during the course of their illness. There were two main objectives: firstly, to review the literature on Parkinson's disease and summarise those factors most often associated with hallucinations; secondly, to carry out a clinical comparison of ambulant patients with Parkinson's disease with and without visual hallucinations, and provide a detailed phenomenological analysis of the hallucinations.

METHODS

A systematic literature search using standard electronic databases of published surveys and case-control studies was undertaken. In parallel, a two stage questionnaire survey was carried out based on members of a local branch of the Parkinson's Disease Society and followed up with a clinical interview.

RESULTS

The review disclosed common factors associated with visual hallucinations in Parkinson's disease including greater age and duration of illness, cognitive impairment, and depression and sleep disturbances. The survey comprised 21 patients with visual hallucinations and 23 without. The hallucinators had a longer duration and a greater severity of illness, and tended to show more depressed mood and cognitive impairment. The typical visual hallucination in these patients is a complex visual image experienced while they are alert and have their eyes open. The image appears without any known trigger or voluntary effort, is somewhat blurred, and commonly moves. It stays present for a period of "seconds" or "minutes". The content can be variable within and between hallucinators, and includes such entities as people, animals, buildings, or scenery. These features resemble those highlighted in hallucinations in the visually impaired (Charles Bonnet's syndrome).

CONCLUSION

A consistent set of factors are associated with visual hallucinations in Parkinson's disease. The results of the phenomenological survey and those of visual hallucinations carried out in other settings suggest a common physiological substrate for visual hallucinations but with cognitive factors playing an as yet unspecified role.