Repeated visual hallucinations in Parkinson's disease as disturbed external/internal perceptions: Focused review and a new integrative model

The changing face of Parkinson's disease-associated psychosis: a cross-sectional study based on the new NINDS-NIMH criteria

New criteria for Parkinson's disease-associated psychosis (PDAP) were recently proposed by a NINDS-NIMH working group. We assessed 116 consecutive unselected outpatients with PD for the existence of psychotic symptoms during the previous month, using a structured questionnaire covering the whole spectrum of PDAP symptoms. Hallucinations occurred in 42% of the patients (visual: 16%; nonvisual: 35%), delusions in 4%, and minor symptoms in 45% (sense of presence, visual illusions, or passage hallucinations). The prevalence of PDAP was 43% when the usual definition was used (hallucinations and/or delusions) and 60% when the NINDS-NIHM criteria were used. Correlations between PDAP and patient characteristics varied with the definition of PDAP. These findings suggest that the epidemiology of PDAP should be re-evaluated with the new criteria. Minor symptoms and nonvisual hallucinations are an important part of the PDAP spectrum, which has commonly been restricted to visual hallucinations and delusions.

Parkinson's disease as a disconnection syndrome

Parkinson's disease (PD) is a major neurodegenerative disorder that is usually considered in terms of midbrain and basal ganglia dysfunction. Regarding PD instead as a disconnection syndrome may prove beneficial to understanding aspects of cognition, perception, and other neuropsychological domains in the disease. PD is usually of unilateral onset, providing evidence of intrahemispheric dissociations and an imbalance in the usual relative strengths of the right and left hemispheres. Hence, in order to appreciate the neuropsychology of PD, it is important to apply to this disease our understanding of hemispheric lateralization effects and within-hemisphere circuitry from brainstem to higher-order association cortex. The focus of this review is on the relevance of PD-related disconnections among subcortical and cortical structures to cognition, perception, emotion, and associated brainstem-based domains such as sleep and mood disturbance. Besides providing information on disease characteristics, regarding PD as a disconnection syndrome allows us to more completely understand normal brain-behavior relations in general.

Scales to evaluate psychosis in Parkinson's disease

Hallucinations and psychotic behaviors are a frequent non-motor aspect of Parkinson's disease and its treatment. These behaviors usually do not occur in the presence of the physician and are therefore difficult to rate. Further, because of their bizarre nature, hallucinations are frequently underreported by patients, and caregivers are often unaware of them until they become problematic. A number of scales have been developed for rating these behaviors, most of them borrowed or adapted from assessment tools used in other psychotic disorders like schizophrenia. In the latter disorders, however, hallucinations and psychosis are phenomenologically different than the typical hallucinations of Parkinson's disease. The Movement Disorder Society Task Force on Parkinson's Disease Rating Scales has completed a systematic critique of scales used in clinical trials focusing on hallucinations and psychosis. In this critique, the following scales met the criteria to be classified as Recommended: Neuropsychiatric Inventory, Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale, and Schedule for Assessment of Positive Symptoms. However, the Task Force felt that each of these scales has significant weaknesses and is insufficient to be considered a definitive rating tool. The Task Force officially recommended the development of a new scale to assess hallucinations and psychosis in Parkinson's disease. This effort is now ongoing with official endorsement by the Movement Disorder Society.

Attentional and perceptual impairments in Parkinson's disease with visual hallucinations

Visual hallucinations (VH) are common in Parkinson's Disease (PD). Both deficits of perception and attention seem to play a role in the pathogenesis of VH in PD. However, the possible coexistence of impairments in attention and visual perception in PD with VH is not known. This study investigated both attention and visual perception in non-demented PD patients with VH, compared to PD patients without VH and healthy controls. Fourteen participants were included in each group. All patients were assessed with sustained visual attention and object and space perception tests. Only PD patients with VH showed impairments on object and space perception. In addition, PD patients with and without VH showed impairments on sustained visual attention, being more severely affected in PD patients with VH. Only in PD patients with VH sustained visual attention was associated with a decreased object and space perception. The results of our study thus suggest that in PD patients with VH an impairment of object and space perception, possibly in association with a decreased sustained visual attention, might play a role in the pathogenesis of VH.

The challenge of non-motor symptoms in Parkinson's disease

The non-motor symptoms (NMS) of Parkinson's disease (PD) are often poorly recognized and inadequately treated in contrast to motor symptoms and a modern holistic approach to treatment of PD should, therefore, include recognition and assessment of NMS. Certain aspects of the NMS complex of PD can be improved with currently available treatments, both dopaminergic and non-dopaminergic, but other features may be more refractory illustrating the importance of research into more effective drug therapies for the future. The American Academy of Neurology has recently published the first task force guidelines in relation to treatment of NMS of PD.

Hallucinations in Parkinson disease

Patients with Parkinson disease (PD) can experience hallucinations (spontaneous aberrant perceptions) and illusions (misinterpretations of real perceptual stimuli). Of such phenomena, visual hallucinations (VHs) and illusions are the most frequently encountered, although auditory, olfactory and tactile hallucinations can also occur. In cross-sectional studies, VHs occur in approximately one-third of patients, but up to three-quarters of patients might develop VHs during a 20-year period. Hallucinations can have substantial psychosocial effects and, historically, were the main reason for placing patients in nursing homes. Concomitant or overlapping mechanisms are probably active during VHs, and these include the following: central dopaminergic overactivity and an imbalance with cholinergic neurotransmission; dysfunction of the visual pathways, including specific PD-associated retinopathy and functional alterations of the extrastriate visual pathways; alterations of brainstem sleep-wake and dream regulation; and impaired attentional focus. Possible treatments include patient-initiated coping strategies, a reduction of antiparkinson medications, atypical neuroleptics and, potentially, cholinesterase inhibitors. Evidence-based studies, however, only support the use of one atypical neuroleptic, clozapine, and only in patients without dementia. Better phenomenological discrimination, combined with neuroimaging tools, should refine therapeutic options and improve prognosis. The aim of this Review is to present epidemiological, phenomenological, pathophysiological and therapeutic aspects of hallucinations in PD.

Hallucinations: Etiology and clinical implications

The literature on hallucinations is reviewed, including history; theoretical background from physiological, biochemical and psychological points of view; classification; causation; presentation in different psychiatric and neurological disorders and in normal persons. The available evidence suggests that hallucinations result from a failure of the metacognitive skills involved in discriminating between self-generated and external sources of information. Management of hallucinations is briefly discussed.

Visual object recognition and attention in Parkinson's disease patients with visual hallucinations

Visual hallucinations (VH) are common in Parkinson's disease (PD) and are hypothesized to be due to impaired visual perception and attention deficits. We investigated whether PD patients with VH showed attention deficits, a more specific impairment of higher order visual perception, or both. Forty-two volunteers participated in this study, including 14 PD patients with VH, 14 PD patients without VH and 14 healthy controls (HC), matched for age, gender, education level and for level of executive function. We created movies with images of animals, people, and objects dynamically appearing out of random noise. Time until recognition of the image was recorded. Sustained attention was tested using the Test of Attentional Performance. PD patients with VH recognized all images but were significantly slower in image recognition than both PD patients without VH and HC. PD patients with VH showed decreased sustained attention compared to PD patients without VH who again performed worse than HC. In conclusion, the recognition of objects is intact in PD patients with VH; however, these patients where significantly slower in image recognition than patients without VH and HC, which was not explained by executive dysfunction. Both image recognition speed and sustained attention decline in PD, in a more progressive way if VH start to occur.

Hallucinations, dreaming, and frequent dozing in Parkinson disease: impact of right-hemisphere neural networks

OBJECTIVE

To relate sleep disturbances in Parkinson disease (PD) to hemispheric asymmetry of initial presentation.

BACKGROUND

Sleep disturbances are common in PD arising from the neurodegenerative process underlying the disease, which is usually lateralized at onset. Patients with left-side Parkinson disease onset (LPD: right hemisphere dysfunction) exhibit reduced vigilance relative to those with right-side Parkinson disease onset (RPD: left hemisphere dysfunction), leading us to hypothesize that sleep-related disturbances, particularly excessive daytime sleepiness, would be more severe for LPD than for RPD.

METHODS

Thirty-one nondemented participants with PD (17 RPD and 14 LPD) and 17 age-matched control (CO) participants with chronic health conditions were administered the Parkinson Disease Sleep Scale and polysomnography was performed on a subset of the PD participants.

RESULTS

Both PD subgroups exhibited more nighttime motor symptoms than the CO group, but only LPD endorsed more nocturnal hallucinations and daytime dozing. Controlling for mood additionally revealed more vivid dreaming in LPD than RPD. There were no significant differences between LPD and RPD on measures of sleep architecture.

CONCLUSIONS

Increased dreaming, hallucinations, and daytime somnolescence in LPD may be related to changes in right-hemisphere neural networks implicated in the generation and control of visual images, arousal, and vigilance. Our results underscore the need to consider side of onset in regard to sleep disturbances in PD.

Functional brain changes in early Parkinson's disease during motor response and motor inhibition

Motor impairment represents the main clinical feature of Parkinson's disease (PD). Cognitive deficits are also frequently observed in patients with PD, with a prominent involvement of executive functions and visuo-spatial abilities. We used event-related functional MRI (fMRI) and a paradigm based on visual attention and motor inhibition (Go/NoGO-task) to investigate brain activations in 13 patients with early PD in comparison with 11 healthy controls. The two groups did not report behavioural differences in task performance. During motor inhibition (NoGO-effect), PD patients compared to controls showed an increased activation in the prefrontal cortex and in the basal ganglia. They also showed a reduced and less coherent hemodynamic response in the occipital cortex. These results indicate that specific cortico-subcortical functional changes, involving not only the fronto-striatal network but also the temporal-occipital cortex, are already present in patients with early PD and no clinical evidence of cognitive impairment. We discuss our findings in terms of compensatory mechanisms (fronto-striatal changes) and preclinical signs of visuo-perceptual deficits and visual hallucinations.

Early Parkinson's disease and non-motor issues

Non motor symptoms (NMS) of PD are a key determinant of health, quality of life and societal cost of PD. Contrary to common perception, many NMS of PD occur early in PD and some may even predate the diagnosis of PD which is based on motor signs. These include olfactory deficit, sleep problems such as REM behaviour disorder, contipation and the more recently described male erectile dysfunction. The non motor quesionnaire (NMSQuest) and the recently validated NMS scale allow falgging and quantification of NMS of PD and therefore are important tools to comprehensively assess symptom load in PD.

The safety of dopamine agonists in the treatment of Parkinson's disease

Dopamine agonists are highly effective as adjunctive therapy to levodopa in advanced Parkinson's disease. These drugs have rapidly gained popularity as a monotherapy in the early stages of Parkinson's disease for patients < 65-70 years old, because they are about as effective as levodopa, but patients demonstrate a lower tendency to develop motor complications. However, dopamine agonists could have peripheral and central side effects, which are often the reason for the discontinuation of the treatment. This review focuses on the potential negative effects related to the use of dopamine agonists in the treatment of Parkinson's disease.

Executive dysfunction in non-demented Parkinson's disease patients with hallucinations

OBJECTIVE

We investigated executive function in Parkinson's disease (PD) patients, and focused on executive dysfunction in PD with hallucinations, but without dementia.

METHODS

PD patients were classified by cognitive or neuropsychotic status as PD group, PD with vivid dreaming group, PD with hallucinations group and Parkinson's disease dementia (PDD) group. Psychomotor speed tests, the Stroop test, a verbal fluency test and the Self-rating Depression Scale were performed.

RESULTS

The PDD group showed poorer scores in every test compared with the PD group. The PD with hallucinations group showed results similar to those of the PDD group, while the PD with vivid dreaming group was similar to the PD group.

CONCLUSIONS

The study suggests that PD patients with hallucinations, not extensive enough to qualify as dementia, already have executive dysfunction similar to that seen in PDD patients. Executive dysfunction may be an important substrate for hallucinations even when dementia is not yet apparent.

Psychosis in Parkinson's disease: phenomenology, frequency, risk factors, and current understanding of pathophysiologic mechanisms

Psychosis in Parkinson's disease refers to a combination of hallucinations and delusions occurring with a clear sensorium and a chronic course. Hallucinations may involve several sensory modalities. Complex visual hallucinations are the most common type. "Minor" hallucinatory phenomena are frequently present and include visual illusions, passage hallucinations, and sense of presence. Insight may be lost in patients with cognitive impairment. Delusions of a paranoid type are more rare than hallucinations. Both hallucinations and delusions are more frequent in Parkinson's disease patients with dementia. Pathogenesis involves complex and probably multifactorial mechanisms, including pharmacologic (dopaminergic treatment and others) and disease-related factors.

New approaches to understanding hallucinations in Parkinson's disease: phenomenology and possible origins

The authors review current literature on hallucinations in Parkinson's disease (PD). Recent neuropathological studies showed that hallucinations occur in synucleinopathies and are a significant predictor of Lewy Body depositions. Therefore, hallucinations are a hallmark of PD and of dementia with Lewy Bodies. Visual hallucinations are mostly complex and kinematic; preserved or disturbed insight on the nature of hallucinations is a major prognostic factor, although eventually all hallucinators will present with reduced insight. Current theories on the origin of hallucinations point to visual dysfunction, dream overflow and cognitive impairment, yet objection can be raised on each one of the putative models of hallucinations. Understanding of the origin of hallucinations is required in order to develop treatments: all treatment evaluations were focused in general on psychosis, and only clozapine obtained positive evidence-based ratings on efficacy. However, it is likely that cholinesterase inhibitors, antipsychotics and anti-5-hydroxytryptamine(3) agents and drugs acting on sleep regulation will have different and perhaps opposite effects on different types of hallucinations, whether they are accompanied by disturbed insight, sleep disorders or other psychotic features. Further studies will try to separate phenomenology and responses to treatment and will investigate the relevance of concomitant sleep disorders and abnormality of frontoparietal networks involved in the attention process.

Association of visual hallucinations with reduction of MIBG cardiac uptake in Parkinson's disease

BACKGROUND

Postganglionic cardiac sympathetic denervation is evident in patients with Parkinson's disease (PD) and iodine-123 metaiodobenzylguanidine ((123)I-MIBG) cardiac scintigraphy has proven to be a useful tool for diagnosis of PD.

OBJECTIVE

To elucidate the factors associated with severity of cardiac sympathetic nerve dysfunction in PD patients.

METHODS

We investigated 95 PD patients hospitalized in the Department of Neurology at Tottori University Hospital. (123)I-MIBG cardiac scintigraphy was performed on each patient and the early and delayed heart to mediastinum (H/M) ratios and washout rate (WR) of (123)I-MIBG cardiac scintigraphy were calculated. Independent predictive variables for parameters of (123)I-MIBG cardiac scintigraphy were analyzed by multivariate regression analysis.

RESULTS

Multivariate regression analysis revealed that the presence of visual hallucinations (VH) and the patient's age at the time of evaluation independently predicted the early or delayed H/M ratio. Analysis of covariance, adjusted for the age of the patients as covariates, revealed that the early and delayed H/M ratios of PD patients with VH but no dementia, as well as PD patients with dementia were significantly lower than the ratios in PD patients with no VH or dementia.

CONCLUSION

Cardiac sympathetic dysfunction may be associated with the presence of VH in PD patients.

A neuropsychological longitudinal study in Parkinson's patients with and without hallucinations

The aim of this work was to determine the progression of cognitive impairment in Parkinson's disease (PD) patients with or without hallucinations. Two years after the first assessment, 36 PD patients were re-evaluated on standardized neuropsychological tests, including the Frontal Assessment Battery (FAB), and on rating scales for overall cognitive functioning, functional autonomy, behavioral disorders. Nine patients had hallucinations at baseline and endpoint assessments; 12 patients developed hallucinations during the follow-up; and 15 patients were hallucination-free throughout the study. Cognitive performance significantly declined in all three groups, but at endpoint assessment PD hallucinators scored significantly lower than nonhallucinators on phonological and semantic fluency tasks, immediate free recall and the go/no-go FAB subtest; moreover, they showed more severe apathy than nonhallucinators. Reduced phonological fluency at baseline (odds ratio [OR], 13.5; 95% CI: 1.34-135.98, P = 0.027) was the only independent predictor of onset of hallucinations after 2 years, whereas hallucinations (OR, 10.1; 95% CI: 1.94-51.54, P = 0.006) and poor phonological fluency (OR, 6.1; 95% CI: 1.04-35.03, P = 0.045) independently predicted development of diffuse cognitive impairment. We concluded that reduced verbal fluency scores may predict the onset of hallucinations, while hallucinations and poor phonological fluency may predict development of dementia in PD patients.

Diagnostic criteria for psychosis in Parkinson's disease: report of an NINDS, NIMH work group

There are no standardized diagnostic criteria for psychosis associated with Parkinson's disease (PDPsy). As part of an NIH sponsored workshop, we reviewed the existing literature on PDPsy to provide criteria that distinguish PDPsy from other causes of psychosis. Based on these data, we propose provisional criteria for PDPsy in the style of the Diagnostic and Statistical Manual of Mental Disorders IV-TR. PDPsy has a well-characterized temporal and clinical profile of hallucinations and delusions, which is different than the pattern seen in other psychotic disorders such as substance induced psychosis or schizophrenia. PDPsy is associated with a poor prognosis of chronic psychosis, nursing home placement, and death. Medications used to treat Parkinson's disease (PD) contribute to PDPsy but may not be sufficient or necessary contributors to PDPsy. PDPsy is associated with Lewy bodies pathology, imbalances of monoaminergic neurotransmitters, and visuospatial processing deficits. These findings suggest that PDPsy may result from progression of the disease process underlying PD, rather than a comorbid psychiatric disorder or drug intoxication. PDPsy is not adequately described by existing criteria for psychotic disorders. We established provisional diagnostic criteria that define a constellation of clinical features not shared by other psychotic syndromes. The criteria are inclusive and contain descriptions of the full range of characteristic symptoms, chronology of onset, duration of symptoms, exclusionary diagnoses, and associated features such as dementia. These criteria require validation and may be refined, but form a starting point for studies of the epidemiology and pathophysiology of PDPsy, and are a potential indication for therapy development.

Selective diplopia in Parkinson's disease: a special subtype of visual hallucination?

Diplopia is sometimes reported by patients with Parkinson's disease (PD) without apparent oculomotor disorders. We assessed clinical features and associated oculomotor and perceptual performance in 14 patients (6 male, 8 female) with PD with a peculiar type of selective diplopia. Duplication of images was confined to single objects or persons, occurred repetitively, and lasted few seconds in all subjects. Frequency of episodes ranged from several episodes per day to three episodes per year. In six of seven subjects undergoing comprehensive ophtalmological examination, subtle ocular disorders (heterophoria, strabism, etc.) were found. Nine of 14 patients were suffering from current or previous visual hallucinations and 3 more patients developed hallucinations within 3 years of diplopia onset. Selective diplopia of isolated single objects and persons in PD is possibly related to hallucinosis and minor ocular disturbances seem to be a triggering factor for this peculiar type of misperception.

Clinical evaluation of Parkinson's disease dementia: association with aging and visual hallucination

OBJECTIVES

In order to explore factors associated with the development of dementia in Parkinson's disease (PD) and Dementia with Lewy bodies (DLB), we systematically investigated the clinical evaluation of PD and DLB patients hospitalized in the Department of Neurology at Tottori University Hospital, Japan.

RESULTS

There were 208 patients diagnosed as having PD and 39 patients diagnosed with DLB in this study. Of the patients with PD, 67 (32%) developed dementia and only five PD+ patients were considered to have cognitive impairment attributable to Alzheimer's disease (AD) or vascular dementia (VaD). Fifty-four (81%) PDD patients had visual hallucinations (VH) with or without cognitive fluctuation. The onset age of parkinsonian motor symptoms of patients with PD dementia (PDD) did not differ from that of PD patients without dementia. There was a significant inverse correlation between the onset age of motor symptoms in PD and the onset of their dementia in PDD. Seventy-five (36%) patients with PD had experienced VH and most of the PDD patients had experienced VH within 1 year before or after diagnosis of PDD.

CONCLUSIONS

These results indicate that aging and VH are important factors associated with dementia in PD.

Cognitive changes in Parkinson's disease patients with visual hallucinations

OBJECTIVE

To evaluate the decline in specific neuropsychological functions in nondemented Parkinson's disease (PD) patients with a history of visual hallucinations (VH).

METHODS

Twenty PD patients with VH, 20 PD patients without VH and 18 normal controls were followed up over a 1-year period and assessed for cognitive decline.

RESULTS

Forty-five percent of nondemented hallucinating PD patients developed dementia during the 1-year period between baseline and follow-up evaluations. Of the nondemented hallucinating PD patients nearly 70% showed impairment in multiple cognitive domains. The progressive decline in hallucinating PD patients affected mainly visual memory for faces and visuoperceptive-visuospatial functions.

CONCLUSION

Our results support a fast impairment of complex visual functions in hallucinating PD patients, but also a progressive decline in multiple cognitive domains, which have been identified as a risk of developing dementia in PD.

[The neurology of REM sleep. A synoptic tour de force]

REM or dreaming sleep is one of three states of consciousness. It is characterized by rapid eye movements, muscle atonia, desynchronized EEG, and autonomic dysregulation. A dysfunction of one of these four cardinal traits explains the primary disorders of REM sleep, including REM sleep behavior disorder and narcolepsy. Although seen in other stages, sleep apnea syndrome, coronary syndromes, and stroke are strongly triggered by the autonomic dysregulation of REM sleep. REM sleep has an antiepileptic effect, which has not yet been used in clinical practice. It favors procedural memory, but not declarative memory. While present neurophysiologic theories, backed up by new neuroimaging techniques, preferentially explore the genesis of REM sleep, psychodynamic theories have searched for its raison d'être by focusing on mentally stabilizing or purifying effects of dreaming. The exploding interest in dreaming sleep, images, and imaging may also yield a harvest for clinical medicine, and further perplexing findings, such as RBD as harbinger of parkinsonism should be expected.

Hypoperfusion of the visual pathway in parkinsonian patients with visual hallucinations

Little is known about the developing mechanisms of visual hallucinations in Parkinson's disease. This study aimed to investigate perfusion changes in parkinsonian patients with visual hallucinations using n-isopropyl-p-[123I]iodoamphetamine ([123I]IMP) single photon emission computed tomography imaging. A total of 70 consecutive patients, including 31 patients with visual hallucinations, and 39 patients without hallucinations, participated in this study. Patients with severe cognitive impairment (Mini-Mental State Examination score < 20), nonvisual hallucinations, or confusion were excluded. We compared brain perfusion changes between the two groups. We found that hallucinatory patients had significant perfusion reductions in the bilateral inferior parietal lobule, inferior temporal gyrus, precuneus gyrus, and occipital cortex compared to nonhallucinatory patients. These results suggested that hypoperfusion of the visual pathway was closely related to visual hallucinations in Parkinson's disease.

Neuropsychological deficits in Parkinson's disease patients with visual hallucinations

Recent neuropathological and neuroimaging studies suggest the involvement of several temporal regions in Parkinson's disease (PD) patients with visual hallucinations (VH). We examined 24 nondemented PD patients with VH, 21 PD patients without VH, and 21 healthy controls using a battery of tests assessing different aspects of temporal lobe function. PD patients with VH showed poorer performance in language, verbal learning, semantic fluency, and visuoperceptive functions compared to controls and PD patients without VH. Differences in verbal learning and visuoperceptive functions were independent of general cognitive status, disease severity, and depression. We suggest that a wide range of neuropsychological deficits can contribute to the emergence of VH in PD.

Non-motor symptoms in Parkinson's disease: an underdiagnosed problem

Parkinson's disease results from degeneration of the substantia nigra pars compacta and the consequent dysfunction of the dopaminergic nigrostriatal pathway. Serotonergic and noradrenergic pathways are also affected. However, It has been recognized that nondopaminergic and non-motor symptoms are sometimes present prior to diagnosis and these inevitably emerge with disease progression, impacting on morbidity, quality of life and mortality. The non-motor symptoms of Parkinson's disease continue to be poorly recognized and inadequately treated in contrast with motor symptoms, and a modern holistic approach to treatment of Parkinson's disease should therefore include recognition and assessment of non-motor symptoms. Certain aspects of the non-motor symptoms complex of Parkinson's disease can be improved with currently available treatments, but other features may be more refractory and require research into effective nondopaminergic drug therapies for the future.

Cognitive deficits and psychosis in Parkinson's disease: a review of pathophysiology and therapeutic options

Parkinson's disease is a neurodegenerative disorder causing not only motor dysfunction but also cognitive, psychiatric, autonomic and sensory disturbances. Symptoms of dementia and psychosis are common: longitudinal studies suggest that up to 75% of patients with Parkinson's disease may eventually develop dementia, and the prevalence of hallucinations ranges from 16-17% in population-based surveys to 30-40% in hospital-based series. These cognitive and behavioural features are important in terms of prognosis, nursing home placement and mortality. The pattern of cognitive deficits in Parkinson's disease is variable, but often includes executive impairment similar to that seen in patients with frontal lesions, as well as episodic memory impairment, visuospatial dysfunction and impaired verbal fluency. The most common manifestation of psychosis in Parkinson's disease is visual hallucinations, but delusions, paranoid beliefs, agitation and florid psychosis can also occur. An understanding of the pathophysiology underlying these symptoms is essential to the development of targeted therapeutic strategies. Post-mortem studies suggest an association between Lewy body deposition and dementia in Parkinson's disease, and indeed Parkinson's disease and dementia with Lewy bodies may form part of the same disease spectrum. Whether Lewy bodies actually play a causative role in cognitive dysfunction, however, is unknown. Deficits in neurotransmitter systems provide more obvious therapeutic targets and dysfunction of dopaminergic, cholinergic, noradrenergic and serotonergic systems have all been implicated; these may each underlie different features of Parkinson's disease dementia, perhaps explaining some of the heterogeneity of the syndrome. Psychosis has traditionally been considered as a dopaminergic drug-induced phenomenon, but factors intrinsic to the disease process itself also cause hallucinations and delusions. These factors may include Lewy body deposition in the limbic system, cholinergic deficits and impairments of primary visual processing. Therapeutic intervention for cognitive and behavioural symptoms in Parkinson's disease currently focuses on two main groups of drugs: cholinesterase inhibitors and atypical antipsychotics. A recent large, randomised, controlled trial suggests that cholinesterase inhibitors can produce a modest improvement in cognitive function, as well as psychotic symptoms, generally without an adverse effect on motor function. Certain atypical antipsychotics allow hallucinations, delusions and behavioural problems to be brought under control with minimal deleterious effects on motor function and cognition, but their safety in elderly patients has recently been called into question. Deep brain stimulation does not appear to be a useful treatment for cognitive and psychiatric dysfunction in patients with Parkinson's disease. Modafinil improves alertness in Parkinson's disease and warrants further investigation to establish its effects on cognitive performance.

Neuropsychiatry of complex visual hallucinations

OBJECTIVE

To describe the phenomenology and pathophysiology of complex visual hallucinations (CVH) in various organic states, in particular Charles Bonnet syndrome and peduncular hallucinosis.

METHOD

Three cases of CVH in the setting of pontine infarction, thalamic infarction and temporoparietal epileptiform activity are presented and the available psychiatric, neurological and biological literature on the structures of the central nervous system involved in producing hallucinatory states is reviewed.

RESULTS

Complex visual hallucinations can arise from a variety of processes involving the retinogeniculocalcarine tract, or ascending brainstem modulatory structures. The cortical activity responsible for hallucinations results from altered or reduced input into these regions, or a loss of ascending inhibition of their afferent pathways.

CONCLUSIONS

A significant degree of overlaps exists between the concepts of Charles Bonnet syndrome and peduncular hallucinosis. The fluidity of these eponymous syndromes reduces their validity and meaning, and may result in an inappropriate attribution of the underlying pathology. An understanding of how differing pathologies may produce CVH allows for the appropriate tailoring of treatment, depending on the site and nature of the lesion and content of perceptual disturbance.

Visual hallucinations in Parkinson's disease: clues to separate origins

Our paper discusses two experimental studies suggesting that Visual Hallucinations (VH) in Parkinson's Disease (PD) may have separate origins. The first is a prospective 8years study evaluating the appearance of VH, visual abnormalities assessed by Visual Evoked Potentials (VEPs) and REM sleep Behaviour Disorder (RBD), in 80 PD patients treated with l-Dopa and Dopaminoagonists (DA). In chronically treated, cognitively unimpaired, PD patients VH were statistically related (p=0.001) to RBD occurrence and high DA doses. Visual abnormalities were significantly reduced by l-Dopa or DA intake, and were statistically unrelated to VH. The second study involved PD patients placed in a Virtual Reality Environment, to decontextualize visual input. When motor symptoms worsened and VEP abnormalities developed patients consistently described hallucinatory dysperceptions of the virtual environment. The two studies therefore show that VH can occur in two seemingly distinct conditions, one is related to chronic treatment and to a sleep disorder frequently observed in PD, the other is probably related to a hypodopaminergic state. Our studies support a recently proposed integrative model of VH, and show that the neural circuits purported to explain VH must include the retinal dopaminergic system and the REM sleep regulatory system.

Psychosis in Parkinson's disease: case studies

Psychosis is common in patients who have PD and leads to significant disability. Patients often can be managed with non-pharmacologic interventions or with decreasing doses of anti-parkinsonism medications. If these interventions are insufficient, then atypical antipsychotics should be considered. Clozapine is used in more refractory cases and requires stringent monitoring for agranulocytosis.

Non-motor symptoms of Parkinson's disease: diagnosis and management

The clinical diagnosis of Parkinson's disease rests on the identification of the characteristics related to dopamine deficiency that are a consequence of degeneration of the substantia nigra pars compacta. However, non-dopaminergic and non-motor symptoms are sometimes present before diagnosis and almost inevitably emerge with disease progression. Indeed, non-motor symptoms dominate the clinical picture of advanced Parkinson's disease and contribute to severe disability, impaired quality of life, and shortened life expectancy. By contrast with the dopaminergic symptoms of the disease, for which treatment is available, non-motor symptoms are often poorly recognised and inadequately treated. However, attention is now being focused on the recognition and quantitation of non-motor symptoms, which will form the basis of improved treatments. Some non-motor symptoms, including depression, constipation, pain, genitourinary problems, and sleep disorders, can be improved with available treatments. Other non-motor symptoms can be more refractory and need the introduction of novel non-dopaminergic drugs. Inevitably, the development of treatments that can slow or prevent the progression of Parkinson's disease and its multicentric neurodegeneration provides the best hope of curing non-motor symptoms.

Visual hallucinations in the diagnosis of idiopathic Parkinson's disease: a retrospective autopsy study

BACKGROUND

For many years, visual hallucinations (VH) in idiopathic Parkinson's disease (PD) were thought to be a complication of antiparkinsonian treatment. The cause of VH is now thought to be nerve-cell loss and Lewy-body pathology in the ventral-temporal regions of the brain. However, the use of VH as a clinical sign of PD has not been investigated.

METHODS

788 cases with parkinsonism archived at the Queen Square Brain Bank for Neurological Diseases were identified for study. Patients had not been given standardised antemortem assessments. Clinical records were assessed for reports of VH. The incidence of VH in pathologically diagnosed cases was calculated, and factors affecting onset of VH were investigated.

FINDINGS

VH occurred in 50% (221/445) of patients with PD, in 73% (32/44) with dementia with Lewy bodies (DLB), and in only 7% (18/255) of patients with non-Lewy-body parkinsonism. The specificity of VH for Lewy-body parkinsonism (PD and DLB combined) was 92.9% (95% CI 89.1-95.8) and the positive predictive value was 93.4% (89.7-95.8). VH were associated with cognitive dysfunction (hazard ratio 5.62, 3.37-9.35), autonomic dysfunction (3.13, 1.77-5.52), axial rigidity (2.22, 1.26-3.85) within the first 2 years of disease onset and also age of onset (1.05, 1.03-1.07). In PD, the onset of VH typically occurred in the second half of the disease course, and time to onset of VH was only weakly correlated with use of selegiline (Spearman's rho 0.22, p=0.005) and ergot dopamine agonists (0.24, p=0.006) but not correlated with use of levodopa, amantadine, or anticholinergic drugs.

INTERPRETATION

The presence of VH is helpful in the differentiation of PD from other non-Lewy-body causes of parkinsonism. We propose that VH be added, as a supportive criterion, to the operational clinical criteria for the diagnosis of PD.

The non-motor symptom complex of Parkinson’s disease: A comprehensive assessment is essential

Parkinson's disease (PD) is a progressive disease that usually affects the motor system but is also associated with a non-motor symptom (NMS) complex that ranges from dribbling saliva, constipation, depression, sleep disorders, apathy, hallucinations, and dementia. These features contribute significantly to morbidity and institutionalization, more than quadrupling the cost of care. Furthermore, recent evidence suggests that NMS such as constipation, olfaction, rapid eye movement behavior disorder, fatigue, and depression may be markers of a preclinical stage of PD. PD-NMS are not well recognized in clinical practice and part of the reason is the lack of any instrument that aims to assess the complex range of NMS of PD in a unified and integrated manner. Recently, an international, multidisciplinary PD-NMS group has developed an integrated questionnaire and scale to assess NMS of PD in a comprehensive manner. This will help improve care and treatment of PD in the future.

Longitudinal evaluation of cerebral morphological changes in Parkinson's disease with and without dementia

OBJECTIVE

To investigate the pattern of brain atrophy across time in a sample of Parkinson's disease (PD) patients with and without dementia using voxelbased morphometry (VBM) analysis.

METHODS

The initial sample comprised thirteen non-demented PD patients and sixteen demented patients. Longitudinal cognitive assessment and structural MRI were performed. The mean follow-up period was 25 months (SD=5.2). From this initial group, eight PD patients with dementia (5 men and 3 women) and eleven PD patients without dementia (7 men and 4 women) were reevaluated. MRI 3D structural images were acquired and analyzed by means of the optimized VBM procedure with Statistical Parametric Mapping (SPM2).

RESULTS

VBM analysis showed a progressive grey matter volume decrease in patients with PD without dementia in limbic, paralimbic and neocortical associative temporooccipital regions. In patients with dementia the loss mainly involved neocortical regions.

CONCLUSION

VBM revealed a significant loss of grey matter volume in PD patients with and without dementia with disease progression. The decrease in limbic and paralimbic regions is widespread in non-demented patients. Neocortical volume reduction is the most relevant finding in patients with dementia. This suggests that the neocortex is a substrate for dementia in Parkinson disease.

Visual hallucinations and the Charles Bonnet syndrome

After dividing clinicians for almost 70 years, Charles Bonnet syndrome has reached an impasse. Defined by a neurologist in the 1930s, the syndrome was intended to eponymize the association of visual hallucinations with age, but evolved into one describing their association with eye disease or, more recently, an etiologically neutral phenomenologic description. Each tradition has its merits but none has defined a specific clinical entity or accounted for visual hallucinations across the spectrum of associated clinical conditions. Recent insights into the neurobiology of vision have shed new light on the problem. Viewed from a neuro-phenomenologic perspective, clinical evidence reveals two distinct hallucination syndromes: one directly related to visual system pathology, the other to pathology in the brainstem or ascending neurotransmitter pathways. The implication is of two independent but interacting pathophysiologic mechanisms and of a need to reassess the classification and management of this common psychopathologic symptom.