Are Parkinson's disease with dementia and dementia with Lewy bodies the same entity?

Cerebral amyloid angiopathy in Lewy body disease

While Alzheimer and Lewy body pathologies are discussed as major substrates of dementia in Parkinson's disease (PD/Lewy body disease of brainstem type), the incidence and impact of cerebral amyloid angiopathy (CAA) and its association with cognitive decline in PD and dementia with Lewy bodies (DLB) are unknown. The severity of CAA and other Alzheimer lesions were assessed in 68 cases of autopsy-confirmed PD, 32 of them with dementia (PDD), and in 20 cases of DLB. PDD patients were significantly older than those without dementia (mean age 84.5 vs 77.6 years; p < 0.01), the age of DLB patients was in between both groups (mean 80.0 years), while duration of disease was DLB < PDD < PD (mean 6.5 vs 8.5 and 14.3 years). PDD patients had a significantly higher neuritic Braak stage (mean 4.2 vs 2.4, p < 0.01), significantly higher cortical amyloid beta (Abeta) load, capillary cerebral amyloid angiopathy (CapCAA) and generalized CAA than those without dementia (mild CapCAA in 22% vs moderate to severe CapCAA in 87%; mild generalized CAA in 5.5% vs moderate to severe generalized CAA in 82%). Mean PD stage was higher in both DLB and PDD than in PD (mean 5.2 vs 4.5 and 4.0, respectively): Mean neuritic Braak stage in DLB was 3.4, severe Abeta plaque load was seen in 95%, moderate to severe CapCAA in 90% and mild to severe generalized CAA in 70%. This and other recent studies imply an association of CAA with cognitive decline in both PD/PDD and DLB, particularly in cases with concomitant AD-type pathology.

Rivastigmine for the treatment of dementia associated with Parkinson's disease

Parkinson's disease (PD) afflicts millions of people worldwide and leads to cognitive impairment or dementia in the majority of patients over time. Parkinson's disease dementia (PDD) is characterized by deficits in attention, executive and visuospatial function, and memory. The clinical diagnostic criteria and neuropathology surrounding PDD remain controversial with evidence of overlap among PDD, dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Cortical cholinergic deficits are greater in PDD than in AD, and are well-correlated with the cognitive and neuropsychiatric dysfunction that occurs in PDD. Inhibition of acetylcholine metabolism is therefore a practical therapeutic strategy in PDD.This review examines current evidence for rivastigmine (a cholinesterase/butyrylcholinesterase inhibitor) treatment in PDD. In addition to its efficacy, we examine the safety profile, side effects, and cost effectiveness of rivastigmine in PDD. Rivastigmine provides modest benefit in PDD and further long-term studies are needed to determine the effectiveness and safety of rivastigmine over time. Tolerability is a problem for many PDD patients treated with rivastigmine. Future studies of rivastigmine in PDD should focus on pragmatic outcomes such as time to need for nursing home placement, pharmacoeconomic outcomes and simultaneous patient/caregiver quality of life assessments.

A comparison of cerebral glucose metabolism in Parkinson's disease, Parkinson's disease dementia and dementia with Lewy bodies

Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) share many similar aspects, and making a clinical diagnosis of one disorder over the other relies heavily on an arbitrary criterion, so-called 1-year rule. This study was designed to search for any difference of metabolic patterns in these two disorders using F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) images. We enrolled 16 patients with PD, 13 patients with PDD, and seven patients with DLB. FDG PET was performed, and images were reconstructed by iterative reconstruction using the computed tomography (CT) images, and were normalized to a standard template. Statistical comparison between groups were performed on a voxel-by-voxel basis using t-statistics (two-sample t-test). Compared with the patients with PD, both PDD and DLB patients showed similar patterns of decreased metabolism in bilateral inferior and medial frontal lobes, and right parietal lobe (P(uncorrected) < 0.001). In a direct comparison, DLB patients had significant metabolic decrease (p(uncorrected) < 0.005) in the anterior cingulate compared with those with PDD. These findings support the concept that PDD and DLB have similar underlying neurobiological characteristics, and that they can be regarded as a spectrum of Lewy body disorders.

A review of cognitive impairments in dementia with Lewy bodies relative to Alzheimer's disease and Parkinson's disease with dementia

Dementia with Lewy bodies (DLB) has recently been identified as a separate disease but diagnosis can be difficult, in particular the differentiation from related dementias of Alzheimer's disease (AD) and Parkinson's disease with dementia (PDD). Careful cognitive assessment may aid differential diagnosis between these different types of dementia and can provide theoretical insight into the nature of the underlying impairments. Recent reviews on DLB have primarily dealt with medical issues of clinical diagnostic criteria, pathology, epidemiology and treatment (Ballard, 2004; Barber et al., 2001; Cercy and Bylsma, 1997; Cummings, 2004; Kaufer, 2004; McKeith, 2002; McKeith et al., 2004a; Rampello et al., 2004) and only a few papers have reviewed cognitive impairments in DLB (Collerton et al., 2003; Lambon-Ralph et al., 2001; Simard et al., 2000). The present paper is more specifically targeted to a neuropsychological audience. It provides an up-to-date, detailed and comprehensive review of the available evidence regarding visual and olfactory perception, attention, cognitive fluctuation, frontal-executive functions, working memory, episodic memory, and semantic memory in DLB relative to AD and PDD. In addition, an attempt is made to relate available data to current theoretical frameworks of cognition. Implications for future research and clinical issues such as the problem of differential diagnosis, and the relation between cognitive impairments and clinical features of visual hallucinations and cognitive fluctuation will be discussed.

Treatment of dementia in parkinsonian syndromes with cholinesterase inhibitors

In Parkinsonian syndromes behavioural symptoms and dementia can be even more debilitating than motor symptoms and are an important predictor for nursing home placement and mortality. Neuropathologically, dementia seems to be primarily related to cortical changes rather than to subcortical alterations. Concerning neurotransmitter systems, the cholinergic system has been proposed to play a key role in cognitive disturbances. Based on studies with patients with Alzheimer disease, the application of cholinesterase inhibitors is vividly discussed also for dementia associated with parkinsonian syndromes. This review focuses on the specific symptoms of dementia in different parkinsonian syndromes and critically questions the effect of cholinergic treatment on cognitive functions in patients with extrapyramidal syndromes and dementia. There is evidence that medication with some cholinesterase inhibitors can enhance cognition as well as activities of daily living in dementia with Parkinson's disease and seems to reduce behavioural disturbances in both dementia with Parkinson's disease and dementia with Lewy bodies. The effect of treatment with cholinesterase inhibitors in progressive supranuclear palsy and corticobasal degeneration warrants carefully designed studies including a sufficient number of patients and symptom-adopted dementia scales.

Management of the behavioral aspects of Parkinson's disease

Parkinson's disease is a progressive and debilitating movement disorder that is diagnosed by its motor signs. The behavioral manifestations of Parkinson's disease are prevalent and frequently complicate the course of the disease. These may be due to the illness itself or its treatment and are often more disabling than the motor symptoms. This review focuses on the management of the most common behavioral symptoms of Parkinson's disease, including depression, anxiety, psychosis, dementia, delirium, sleep disorders, fatigue, apathy, emotionalism and compulsive behaviors.

Rivastigmine and Parkinson dementia complex

Patients suffering from Parkinson's disease dementia (PDD) have a movement disorder, but it can be difficult to determine whether the functional impairment, which is critical in making the assessment of whether a patient has achieved the threshold for a diagnosis of dementia, is due to the dementia or the underlying Parkinson's disease. Although the cognitive impairment found in nondemented patients with Parkinson's disease is very dysexecutive in nature, the DSM IV (Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association IV) diagnosis of PDD has memory impairment as the defining characteristic of PDD. Severe deficits in cortical, cholinergic, excitatory, neuromodulatory input mean that memory impairment is not always due to encoding and retrieval strategy deficits, but it may also be amnesic without being related to concomitant Alzheimer's disease pathology. Patients with PDD have a high mortality, especially when they develop hallucinations and/or are admitted to nursing homes. Of interest is the reduction in mortality that was more marked in the subgroup with visual hallucinations at baseline. The increased mortality in PD may be due to autonomic failure, evidenced by the reductions in heart rate variability in these patients. This reduction is greater in patients with hallucinations. Rivastigmine is a dual inhibitor of brain acetyl- and butyrylcholinesterases that has been evaluated in the symptomatic treatment of patients with mild-to-moderate dementia associated with idiopathic Parkinson's disease. Although there is a need for more studies using pragmatic measures, such as time to residential care facility and both patient and carer quality of life assessments, rivastigmine appears to improve cognition and activities of daily living in patients with PDD, resulting in a clinically meaningful benefit in a large number of cases.

Stanley Fahn Lecture 2005: The staging procedure for the inclusion body pathology associated with sporadic Parkinson's disease reconsidered

The synucleinopathy known as sporadic Parkinson's disease (PD) is a multisystem disorder that severely damages predisposed nerve cell types in circumscribed regions of the human nervous system. A recent staging procedure for the inclusion body pathology associated with PD proposes that, in the brain, the pathological process (formation of proteinaceous intraneuronal Lewy bodies and Lewy neurites) begins at two sites and continues in a topographically predictable sequence in six stages, during which components of the olfactory, autonomic, limbic, and somatomotor systems become progressively involved. In stages 1 to 2, the Lewy body pathology is confined to the medulla oblongata/pontine tegmentum and anterior olfactory structures. In stages 3 to 4, the substantia nigra and other nuclei of the basal mid- and forebrain become the focus of initially subtle and, then, severe changes. During this phase, the illness probably becomes clinically manifest. In the final stages 5 to 6, the lesions appear in the neocortex. This cross-sectional study originally was performed on 168 autopsy cases using material from 69 incidental cases and 41 clinically diagnosed PD patients as well as 58 age- and gender-matched controls. Here, the staging hypothesis is critically reconsidered and discussed.

Fulminant Lewy body disease

The clinical distinction between Parkinson's disease (PD) with dementia (PDD) and dementia with Lewy bodies (DLB) is challenged by most neuropathological studies showing nearly identical changes in both conditions. We report an unusual case of PD evolving into a rapidly progressive dementia leading to death within 3 months that showed nearly all clinical features of DLB. At autopsy, numerous Lewy bodies and Lewy neurites were found in several areas of the brainstem, the limbic system, and the neocortex, consistent with pure DLB. This case demonstrates that Lewy body disease may exhibit a dramatic course without any coexisting pathology and exemplifies that PD, PDD, and DLB may sometimes represent sequential, yet overlapping, phenotypes of a same clinicopathological entity.

Cortical Lewy body disease and Parkinson's disease dementia

PURPOSE OF REVIEW

The health and socioeconomic impacts of dementia with Lewy bodies and dementia associated with Parkinson's disease have become increasingly recognized. Whilst the nosological status of dementia with Lewy bodies has been better classified as 'Lewy body dementias', both conditions are now believed to represent a disease spectrum, characterized pathologically by synuclein protein and clinically by a variable admixture of cognitive, neuropsychiatric and extrapyramidal features.

RECENT FINDINGS

Recent epidemiological studies are described and clinical and pathological similarities emphasized between dementia with Lewy bodies and Parkinson's disease. A number of investigational techniques are highlighted which have helped to better characterize dementia with Lewy bodies and discriminate it from Alzheimer's disease, whilst also shedding light upon the pathophysiology of both conditions. Finally, the therapeutic aspects of the Lewy body dementias will be considered, concentrating upon studies of the cholinesterase inhibitors.

SUMMARY

The pathology underlying dementia with Lewy bodies and Parkinson's disease is heterogeneous, and is neither stereotyped in its topography nor its composition. Cholinesterase inhibitor drugs improve cognition and neuropsychiatric symptoms but the clinical response is unpredictable. Major future challenges are to better understand the pathophysiological basis underpinning the diseases, what determines clinical phenotypic expression and how disease-modifying therapies may best be developed and deployed.

Familial occurrence of dementia and parkinsonism: a systematic review

Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) are common clinical dementias characterized neuropathologically by the presence of cortical Lewy body pathology and with distinct clinical and neurobiological similarities. Importantly, genetic factors seem to play a key role in the pathogenesis of Parkinson's disease. In the current article, we examine the evidence for a genetic component to DLB and PDD by reviewing studies of familial PDD and DLB as well as familial coincidental PDD and DLB, and report the genes involved. There is a convincing genetic overlap between both syndromes, suggesting that they share a common etiological factor.

Neuropsychiatric symptoms in patients with Parkinson's disease and dementia: frequency, profile and associated care giver stress

OBJECTIVE

To explore the profile of neuropsychiatric symptoms in patients with dementia associated with Parkinson's disease (PDD).

METHODS

537 patients with PDD drawn from an international multicentre clinical trial of rivastigmine were assessed using the 10-item Neuropsychiatric Inventory (NPI). A cluster analysis was used to investigate the inter-relationship of NPI items. Associations between the clusters and demographic and clinical variables were analysed.

RESULTS

89% of the patients presented at least one symptom on the NPI, 77% had two or more symptoms and 64% had at least one symptom with a score > or = 4. The most common symptoms were depression (58%), apathy (54%), anxiety (49%) and hallucinations (44%). Patients with more severe dementia and advanced Parkinson's disease had more neuropsychiatric symptoms. Nearly 60% of the care givers reported at least one NPI symptom to be of at least moderate severe distress. Five NPI clusters were identified: one group with few and mild symptoms (52%); a mood cluster (11%, high scores on depression, anxiety and apathy); apathy (24%; high apathy and low scores on other items); agitation (5%, high score on agitation and high total NPI score); and a psychosis cluster (8%; high scores on delusions and hallucinations). The psychosis and agitation clusters had the lowest Mini-Mental State Examination score and the highest Unified Parkinson's Disease Rating Scale and care giver distress scores.

CONCLUSION

Neuropsychiatric symptoms are common in patients with PDD. The profile of these symptoms differs from that in other types of dementia. Subgroups with different neuropsychiatric profiles were identified. These subgroups may be associated with distinct neurobiological changes, which should be explored in future studies.

A novelLRRK2 mutation in an Austrian cohort of patients with Parkinson's disease

To investigate the frequency of mutations in the Leucine-Rich Repeat Kinase 2 gene (LRRK2) in a sample of Austrian Parkinson's disease (PD) patients, we sequenced the complete coding region in 16 patients with autosomal dominant PD. Furthermore, we sequenced exons 31, 35, and 41 additionally in 146 patients with idiopathic PD and 30 patients with dementia with Lewy bodies. Furthermore, all 192 patients were screened for 21 putative LRRK2 mutations. While the most common mutation G2019S and the risk variant G2385R were not found in our samples, we detected a novel missense mutation (S973N) in a patient with familial, late-onset and dopa-responsive PD.

Cognitive, Affective, and Psychiatric Features of Parkinson's Disease

Nonmotor symptoms, including cognitive deterioration and dementia, depression and apathy, and psychosis, are common in Parkinson's disease. Their presence is associated with a tremendous burden for the patient and family members. This article reviews the pathophysiololgy, risks, impact, major features, diagnosis, and treatment of these symptoms in Parkinson's disease.

Does striatal pathology distinguish Parkinson disease with dementia and dementia with Lewy bodies?

The morphological differentiation of Parkinson disease with dementia (PDD) and dementia with Lewy bodies (DLB) is a matter of discussion. The objective of this study was to investigate the regional distribution of beta-amyloid (Abeta) plaques, alpha-synuclein (AS), and pathology in both disorders. The basal ganglia from 17 age-matched patients of PDD and DLB each were immunohistochemically examined with variable degrees of associated Alzheimer pathology using antibodies to Abeta, AS, and tau. DLB brains showed a significantly higher burden of (diffuse) amyloid plaques in the putamen and caudate nucleus and slightly more severe tau pathology than PDD brains despite similar neuritic Braak stages. Phases of Abeta development in DLB brains often, but inconsistently, correlated with both neuritic Braak stages and severity of striatal Abeta load, while these correlations were almost never seen in PDD cases with Alzheimer lesions. They also revealed a higher burden of AS-lesions (both Lewy neurites and Lewy bodies) than PDD cases that commonly had a paucity of all three types of lesion. The globus pallidus was virtually spared in both phenotypes. Differences in AS and Abeta pathologies and much less of tau lesions in the striatum support a morphologic distinction between PDD and DLB, which may be of pathophysiologic importance, but the causes of these differences are unclear.

Use of atypical antipsychotics in neurodegenerative diseases

Behavioral and psychotic disturbances are common symptoms in neurodegenerative disorders, and can lead to caregiver stress, nursing home placement and mortality. There is an expanding literature evaluating the effects of atypical antipsychotic (AA) drugs for treating these problems. The results in both primary dementias and Parkinson’s disease suggest that not all AA drugs are equal in terms of efficacy or safety. Furthermore, Parkinsonian and other side effects of the AAs are important to consider when evaluating outcomes. The recent US FDA warning of increased mortality has increased uncertainty in using these drugs. This article reviews the AAs and their use in Parkinson’s disease, dementia with Lewy bodies, Alzheimer’s disease and other associated dementias.

Phenomenology and management of cognitive and behavioral disorders in Parkinson's disease. Rise and logic of dementia in Parkinson's disease

An overview of studies on the issue of dementia in Parkinson's disease shows that, over time, there has been an evolution in the perception of the magnitude of the problem and of its nature. Dementia seems today to be part of the disease. This change in the understanding of the disease can be accounted for by various methodological problems and by difficulties, on one hand, in the definition of dementia and its differentiation from other conditions, and, on the other hand, in the diagnosis of the disease itself in individual cases. Optimal therapeutic strategies are also examined, either based on cholinesterase inhibitors or antiparkinsonian drugs and symptomatic measures.

Laminar distribution of beta-amyloid deposits in dementia with Lewy bodies and in Alzheimer's disease

This study tested whether the laminar distribution of the beta-amyloid (Abeta) deposits in dementia with Lewy bodies (DLB) cases with significant Alzheimer's disease (AD) pathology (DLB/AD) was similar to "pure" AD. In DLB/AD, the maximum density of the diffuse and primitive deposits occurred either in the upper laminae or a bimodal distribution was present with density peaks in the upper and lower laminae. A bimodal distribution of the classic Abeta deposits was also observed. Compared with AD, DLB/AD cases had fewer primitive deposits relative to the diffuse and classic deposits; the primitive deposits exhibited a bimodal distribution more frequently, and the diffuse deposits occurred more often in the upper laminae. These results suggest that Abeta pathology in DLB/AD may not simply represent the presence of associated AD.

Cholinesterase inhibitors: drugs looking for a disease?

Maggini and colleagues examine the evidence on cholinesterase inhibitors for treating dementia. "What seemed a biologically plausible intervention," they say, "has not led to a proven, real improvement in patients' well-being."

Neuropathology of dementia in Parkinson's disease: a prospective, community-based study

Twenty-two patients with Parkinson's disease drawn from a community-based study were followed prospectively until their deaths. Even though 18 patients had dementia, none fulfilled Braak and Braak or The National Institute on Aging and Ronald and Nancy Reagan Institute of the Alzheimer's Association, whereas all patients had limbic or neocortical Lewy body disease. The Lewy body score and Braak and Braak stage were significantly associated with the rate of cognitive decline, but only the Lewy body score was associated with the rate of cognitive decline in the univariate analyses. This study strongly suggests that Lewy body disease is the main substrate driving the progression of cognitive impairment in Parkinson's disease.

Management of Parkinson???s Disease Dementia

Parkinson's disease dementia (PDD) ultimately develops in about 80% of patients with Parkinson's disease (PD), and cross-sectional studies have found that some 30% of these patients will experience neuropsychiatric symptoms, such as visual hallucinations and psychosis. The most consistently reported risk factors for dementia in PD are age, severe parkinsonism and mild cognitive impairment. In PDD, both subcortical cognitive and cortical cognitive profiles are described. Specific disorders of sleep, such as rapid eye movement sleep behaviour disorder, excessive daytime sleepiness and sleep attacks, occur frequently. Alzheimer and Lewy body pathology coexist, but the Lewy body pathology in limbic and cortical areas seems to be the main cause of dementia. Neurochemical changes in the biogenic amines and acetylcholine are common, and magnetic resonance imaging studies have shown cortical atrophy in wide cortical areas, including the hippocampus. All PD patients should be screened for mild cognitive impairment and dementia. A large randomised clinical trial showed that the cholinesterase inhibitor rivastigmine has desirable effects on cognition and neuropsychiatric symptoms in PDD patients. Atypical antipsychotic agents may improve psychosis in PDD, but the evidence for this is poor and adverse effects from such therapy are common and may be severe. Non-pharmacological interventions can also be effective but require further study.

'Alzheimer's disease': more data, but are we any more informed?

PURPOSE OF REVIEW

While we adhere to traditional misconceptions regarding the nature of age-associated neurodegenerative, and vascular and other brain changes, we will not re-design our research projects, and we will not reconsider and improve our pragmatic diagnostic and therapeutic approach.

RECENT FINDINGS

This review focuses (1) on the continuum of cognitive deficits from mild cognitive impairment to manifest dementia, (2) on the spectrum of neurodegenerative, vascular and other cerebral co-morbidity, and (3) on some reversible examples of the rare outliers (limbic encephalitis, Hashimoto encephalopathy) not to be included in the common severity and cerebral co-morbidity spectrum of senile cognitive impairment.

SUMMARY

We will only be more informed if we accept appropriate concepts and draw the right conclusions. Important new research has not yet filtered into the minds of dementia researchers specializing in 'normal ageing' or 'mild cognitive impairment', 'Alzheimer's disease' or 'dementia with Lewy bodies', tauopathies or synucleopathies, etc.

A systematic review of prevalence and incidence studies of dementia with Lewy bodies

BACKGROUND

Substantial variation in the prevalence of Dementia with Lewy Bodies (DLB) has been reported with estimates ranging from 0 to 26.3% of all dementia cases, potentially making it the second most common dementia subtype.

OBJECTIVES

The aim of this study was to review systematically and critically for the first time previous studies of the clinical prevalence and incidence of DLB in the population.

METHODS

A systematic literature search was performed using PubMed. Selected articles had to describe an original study that provided a prevalence and/or incidence number for the whole population for DLB as defined by pre-set clinical criteria and findings.

RESULTS

Six studies reporting the prevalence of DLB and one study reporting the incidence of DLB met the inclusion criteria. Prevalence estimates, depending on case criteria, range from 0 to 5% with regard to the general population, and from 0 to 30.5% of all dementia cases. The only estimate for DLB incidence is 0.1% a year for the general population and 3.2% a year for all new dementia cases. The number of available studies was too small to hypothesise on the potential effect of age, sex and genetic background on the results.

CONCLUSIONS

Although the literature on the prevalence and incidence of DLB is limited, there is a general consensus that DLB must be considered in the range of neurodegenerative conditions in the elderly. The move towards use of consensus criteria facilitates comparison and is welcome. Their application in a more routine way towards rigorously defined and selected study populations will lead to more comparable and generalisable studies in the future.

The role of levodopa in the management of dementia with Lewy bodies

BACKGROUND

One of the core clinical features of dementia with Lewy bodies (DLB) is extrapyramidal syndrome (EPS). Levodopa is currently the gold standard oral therapy for Parkinson's disease (PD), but its use in DLB has been tempered by concerns of exacerbating neuropsychiatric symptoms.

AIM

To assess the efficacy and tolerability of L-dopa in managing EPS in DLB and to compare the motor response with that seen in PD and PD with dementia (PDD).

METHOD

EPS assessment consisted of the Unified Parkinson's Disease Rating Scale, motor subsection (UPDRS III), and finger tapping and walking tests. Patients with DLB were commenced on L-dopa. After 6 months, patients were examined in the "off" state, given L-dopa and assessed for motor responses. Identical assessments were performed in patients with PD and PDD also receiving L-dopa.

RESULTS

Acute L-dopa challenge in 14 DLB patients yielded a mean 13.8% (p = 0.02) improvement in UPDRS III score, compared with 20.5% in PD (n = 28, p < 0.0001) and 23% in PDD (n = 30, p<0.0001) respectively. Finger tapping scores increased (12.3% v 20% and 23%), while walking test scores decreased (32% v 41% and 67%). Of the DLB patients, 36% were classified as "responders" on L-dopa challenge, compared with 70% of the PDD and 57% of the PD patients. Nineteen DLB patients were treated for 6 months with L-dopa (mean daily dose 323 mg). Two withdrew prematurely with gastrointestinal symptoms and two with worsening confusion.

CONCLUSION

L-dopa was generally well tolerated in DLB but produced a significant motor response in only about one third of patients. Younger DLB cases were more likely to respond to dopaminergic treatment.

Dementia with Lewy bodies and Parkinson's disease with dementia: Are they different?

The relationship of dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD) is debated. In DLB, dementia antedates Parkinsonism; in PDD, Parkinsonism antedates dementia. Other than presenting features, diagnostic measures fail to distinguish DLB from PDD. There are few or no pathologic differences between DLB and PDD. In most cases cortical Lewy bodies (LBs) are widespread and there is coexistent Alzheimer type pathology, insufficient to diagnose Alzheimer's disease. Given the predominance of Parkinsonism in PDD, neuronal loss in the substantia nigra is more severe in PDD than DLB. Further clinicopathologic studies are needed to define other pathologic differences between DLB and PDD and to explore the role of neuritic, basal forebrain and striatal pathology in these clinical syndromes.

Psychiatric aspects of Parkinson's disease

PURPOSE OF REVIEW

Recently, there has been much interest and rapid progress in understanding the neuropsychiatry of Parkinson's disease. This paper reviews the most important papers published during 2004 on dementia and cognitive impairment, depression and psychosis in Parkinson's disease.

RECENT FINDINGS

Many new studies of cognitive impairment and dementia in Parkinson's disease have been published during 2004. Cognitive impairment has been demonstrated even during the first 1-2 years after onset of disease. Whereas executive and attentional impairment is typical, learning deficits occur early in some patients. Both functional and structural imaging suggest that in addition to fronto-subcortical deficits, temporal and parietal changes occur early as well. In the first large placebo-controlled trial, the cholinesterase inhibitor rivastigmine improved cognition, daily functioning and psychiatric symptoms without worsening of parkinsonism. The frequency and characteristics of depression, anxiety and hallucinations have been explored in several studies. Unfortunately, there is still little scientific evidence available to guide the treatment of these important aspects of Parkinson's disease, and adequately designed clinical trials are needed. Although subthalamic stimulation, in addition to improvement of movement, is frequently associated with some affective and cognitive improvement, permanent and significant worsening may occur in some. Future studies should aim at identifying at-risk patients, as well as identifying the optimal pharmacological and stimulation treatments for individual patients.

SUMMARY

These findings provide a deeper understanding of the neurobiological substrate of cognitive impairment and dementia in Parkinson's disease, and provide new information regarding the assessment and management of dementia and other neuropsychiatric aspects of Parkinson's disease.

A systematic review of prevalence studies of dementia in Parkinson's disease

Substantial variation in the prevalence of dementia in Parkinson's disease (PDD) has been reported. The aim of this study was to review systematically and critically previous studies of the prevalence of PDD using PubMed to search the literature. Studies focusing on PD and PDD, as well as those examining on the epidemiology of dementia subtypes, were included. Predefined inclusion and exclusion criteria were used and the quality of the studies included was rated. Articles were included if: (1) the proportion of PDD among patients with either PD or dementia was reported in an original study; (2) patients had been subjected to prospective clinical examination; and (3) strategies to include all subjects with either PD or dementia within the community or hospital clinics within a geographical area were employed. Twelve studies of the prevalence of PD or PDD (1,767 patients included) and 24 prevalence studies of dementia subtypes (4,711 patients included) met the inclusion criteria. In the PD/PDD studies, the proportion (mean and 95% confidence interval) with PDD in PD was 24.5% (17.4-31.5). There were significant methodological variations between studies and in the four studies that matched the quality criteria most closely, the rate of PDD was 31.1% (20.1-42.1). The prevalence of PDD was estimated as 0.5% in subjects 65 years or older. The percentage of PDD among those with dementia was 3.6% (3.1-4.1), with an estimated prevalence of PDD of 0.2% in subjects aged 65 years or older. Despite methodological variation, this systematic review suggests that 24 to 31% of PD patients have dementia, and that 3 to 4% of the dementia in the population would be due to PDD. The estimated prevalence of PDD in the general population aged 65 years and over is 0.2 to 0.5%.