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

Brain volumetrics to investigate aging and the principal forms of degenerative cognitive decline: a brief review

The volume of the brain and of some of its structures can provide insight into the pathological process of several diseases. For this reason, in the recent years we saw a tremendous progress in the development of automated techniques for gaining information about global and regional atrophy. This paper reviews the main methods of analysis to quantify brain volume, and their application to the study of normal aging and the principal forms of degenerative dementias.

Morphometry of the human substantia nigra in ageing and Parkinson's disease

To investigate the relation between the loss of substantia nigra (SN) neurons in normal ageing and Parkinson's disease (PD), we measured the total number and the cell body volume of pigmented (neuromelanin) neurons in the SN. We examined young (n = 7, mean age: 19.9), middle-aged (n = 9, mean age: 50.1), and older controls from the Baltimore Longitudinal Study of Aging (n = 7, mean age: 87.6), as well as PD cases (n = 8, mean age: 74.8). On random-systematically selected paraffin Nissl-stained sections, we used the Optical Fractionator to estimate the total number of neurons on one side of the SN. Using the Nucleator probe, we measured the volume of these neurons. In young and older controls, we also estimated the total number and volume of tyrosine hydroxylase (TH) positive (+) nigral neurons. We observed a significant loss of pigmented (-28.3%, P < 0.01) and TH (+) (-36.2%, P < 0.001) neurons in older controls compared with younger subjects. Analysis of the size distribution of pigmented and TH (+) neurons showed a significant hypertrophy in older controls compared to young controls (P < 0.01). In contrast, in PD we observed a significant atrophy of pigmented neurons compared to all control groups (P < 0.01). These data suggest that neuronal hypertrophy represents a compensatory mechanism within individual SN neurons that allows for normal motor function despite the loss of neurons in normal ageing. Presumably, this compensatory mechanism breaks down or is overwhelmed by the pathological events of PD leading to the onset of the characteristic motor disturbances.

Neuropsychological characteristics of dementia with Lewy bodies and Parkinson's disease with dementia: differentiation, early detection, and implications for "mild cognitive impairment" and biomarkers

Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) are neurodegenerative conditions sharing a disorder of alpha-synuclein metabolism. Temporal differences in the emergence of symptoms and clinical features warrant the continued clinical distinction between DLB and PDD. While DLB and PDD groups' neuropsychological profiles often differ from those in Alzheimer's disease (AD), the diagnostic sensitivity, specificity, and predictive values of these profiles remain largely unknown. PDD and DLB neuropsychological profiles share sufficient similarity to resist accurate and reliable differentiation. Although heterogeneous cognitive changes (predominantly in memory and executive function) may manifest earlier and more frequently than previously appreciated in Parkinson's disease (PD), and executive deficits may be harbingers of dementia, the enthusiasm to uncritically extend the concept of mild cognitive impairment (MCI) to PD should be tempered. Instead, future research might strive to identify the precise neuropsychological characteristics of the prodromal stages of PD, PDD, and DLB which, in conjunction with other potential biomarkers, facilitate early and accurate diagnosis, and the definition of neuroprotective, neurorestorative, and symptomatic treatment endpoints.

Management of non-motor symptoms in advanced Parkinson disease

Progress in pharmacology has markedly improved the treatment of early Parkinson's disease. The management of advanced Parkinson's symptoms, however, remains a challenge. These symptoms are divided into motor and non-motor symptoms. Non-motor symptoms may appear early or late in the disease and sometimes even before the onset of the first motor symptoms confirming the diagnosis. The spectrum of non-motor symptoms encompasses autonomic dysfunctions, sleep disorders, mood disorders, impulse control disorders, cognitive dysfunction, dementia, paranoia and hallucinations. They are often less appreciated than motor symptoms but are important sources of disability for many PD patients. This review describes these non-motor symptoms and their managements.

Clinical diagnostic criteria for dementia associated with Parkinson's disease

Dementia has been increasingly more recognized to be a common feature in patients with Parkinson's disease (PD), especially in old age. Specific criteria for the clinical diagnosis of dementia associated with PD (PD-D), however, have been lacking. A Task Force, organized by the Movement Disorder Study, was charged with the development of clinical diagnostic criteria for PD-D. The Task Force members were assigned to sub-committees and performed a systematic review of the literature, based on pre-defined selection criteria, in order to identify the epidemiological, clinical, auxillary, and pathological features of PD-D. Clinical diagnostic criteria were then developed based on these findings and group consensus. The incidence of dementia in PD is increased up to six times, point-prevelance is close to 30%, older age and akinetic-rigid form are associated with higher risk. PD-D is characterized by impairment in attention, memory, executive and visuo-spatial functions, behavioral symptoms such as affective changes, hallucinations, and apathy are frequent. There are no specific ancillary investigations for the diagnosis; the main pathological correlate is Lewy body-type degeneration in cerebral cortex and limbic structures. Based on the characteristic features associated with this condition, clinical diagnostic criteria for probable and possible PD-D are proposed.

Distinguishing Lewy body dementias from Alzheimer's disease

Lewy body dementia (LBD) is the second most common dementia after Alzheimer's disease (AD). LBD is characterized clinically by visual hallucinations, extrapyramidal symptoms, cognitive fluctuations and neuroleptic sensitivity. LBD and AD share many common features in pathology, genetics and biochemical alterations; however, correct clinical distinction between these disorders has prognostic and therapeutic implications. There are currently no definitive radiological or biological markers for LBD, but studies suggest that premorbid differences in cognitive domains and personality traits, differences in clinical presentation, and alterations in autonomic function and sleep may improve diagnosis. Cholinergic dysfunction plays a major role in both AD and LBD; however, dysfunction is greater in LBD. This may account for the more prominent hallucinations, and offers the possibility of a greater response to cholinesterase inhibitors in LBD. The treatment of LBD is symptomatic and is based on a limited number of clinical trials and extension of results from trials in AD. Current research is focused on the role of synuclein aggregation with possible roles for synuclein-derived peptides as aggregation inhibitors. Other approaches target amyloid, neuroinflammation, oxidative injury, proteolysis, lipid peroxidation and immunotherapies with variable results. Improved understanding of disease mechanisms may open new therapeutic avenues for LBD in the future.

Cognitive decline tracks motor progression and not disease duration in Parkinson patients

We performed an analysis of prospectively-acquired cross sectional data on 106 Parkinson disease (PD) patients who underwent comprehensive neuropsychological testing and the Unified Parkinson Disease Rating Scale (UPDRS) motor scale. A significant correlation between the UPDRS motor and neuropsychological tests in all cognitive domains except for general intelligence and visuo-spatial function was seen. In this study, cognitive decline within this PD cohort correlated with motor impairment but not disease duration. Our findings suggest that overall cognitive impairment (except visuospatial dysfunction) may track motor progression in PD more than duration of disease. Longitudinal studies are needed to confirm our results.

Cognitive impairment in Parkinson's disease

BACKGROUND

Cognitive impairment plays a role in Parkinson's disease (PD) and has important consequences for patient management. However, many aspects of cognitive impairment in PD remain unclear because of the use of different and often invalid measurement instruments. In this study, a reliable and valid instrument, the SCales for Outcomes in PArkinson's disease-COGnition (SCOPA-COG), was used.

AIM

To evaluate cognitive functioning in a large cohort of patients with Parkinson's disease and to assess the relations with demographic, disease related and clinical variables.

METHODS

A cohort of 400 patients with PD was evaluated for cognition, motor and non-motor domains, as well as for demographic and disease related characteristics. Results were compared with 150 controls matched for overall age, sex and education distribution.

RESULTS

Patients with PD scored significantly lower on all cognitive subdomains compared with controls, with the largest differences for executive functioning and memory. After correction for age and years of education, 22% of patients had impaired cognition, as measured by the total SCOPA-COG score, compared with controls. Across all patients, more severe cognitive impairment was associated with significantly more impairment in motor, autonomic, depressive and psychotic domains. Patients with the postural instability gait difficulty (PIGD) dominant phenotype showed more cognitive impairment compared with patients with the tremor dominant phenotype. Contrary to tremor scores, PIGD scores significantly worsened with increasing disease severity.

CONCLUSIONS

Cognition is an important domain of the clinical spectrum of PD and poorer cognitive performance is associated with greater impairment in motor and non-motor domains in PD. The difference in cognitive scores between PIGD dominant patients and tremor dominant patients likely reflects more advanced disease.

Cognitive dysfunctions in mild Parkinson's disease dementia: comparison with patients having mild Alzheimer's disease and normal controls

OBJECTIVE

Although the neuropsychological differences between Alzheimer's disease (AD) and Parkinson's disease dementia (PDD) have been scrutinized in several studies, no study to date has directly compared the cognitive impairment profiles of patients with mild PDD and those with mild AD. In this study, we investigated the cognitive changes of mild PDD patients as compared with age- and education-matched normal controls and matched mild AD patients.

METHODS

Thirty-one patients with PDD, 24 patients with probable AD (pAD), and 50 controls were recruited prospectively. All the subjects were evaluated with a battery of detailed neuropsychological tests for the assessment of attention, memory, language, and the visuospatial and frontal executive functions.

RESULTS

The PDD and pAD groups demonstrated significant impairments in all cognitive domains compared with the control group. These cognitive declines attributable to dementia were similar in the PDD and pAD patients, but they were not identical. In the subdomain analysis, the pAD group demonstrated more marked changes in delayed memory performance than did the PDD group.

CONCLUSIONS

Our result showed that the cognitive changes in mild PDD patients did not differ from those in the mild pAD patients, except for delayed memory items. We concluded that it is difficult to sharply distinguish between mild PDD and mild AD.

Behandlung der Demenz bei Parkinson-Syndromen

In parkinsonian syndromes dementia frequently occurs in the disease progress. The cholinergic system has been proposed as playing a key role in cognitive disturbances. Therefore the application of cholinesterase inhibitors (ChEI) is also hotly argued for dementia associated with parkinsonian syndromes. This review focuses on the specific symptoms of dementia in Parkinson's disease (PDD), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). The effect of cholinergic treatment on cognition and behaviour is reported and critically discussed. There is evidence that medication with some ChEIs reduces cognitive disturbances and to a lesser extent improves activities of daily living in PDD. Behavioural symptoms also seem to be positively influenced by treatment with ChEIs in both PDD and DLB. The effect of treatment with cholinesterase inhibitors in PSP and CBD warrants more carefully designed studies including sufficient numbers of patients.

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.

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.

Diagnostic criteria of dementia

In the past two decades there has been a tremendous effort among clinicians and searchers to improve the diagnostic criteria of the dementias on the basis of the differential neurological and neuropsychological profiles. This was an obligatory requirement for clinical trials and the development of treatments. Over the years it became rapidly evident that the cohorts of patients in studies had some degree of heterogeneity, making it difficult to interpret the results of some studies, particularly in the vascular dementias and the mild cognitive impairment (MCI) group. For example, many sub-types of the vascular group were included in clinical trials, such as the cortical strokes, the lacunar states and the diffuse white matter disease cases, and some of the patients might have had also mixed pathology. In addition, the standard DSM IV criteria for dementia no longer represent our present knowledge of the clinical profile of some of the dementias such as vascular dementia (VaD) and fronto-temporal dementia where the memory impairment is not necessarily the first requirement. To improve the validity of clinical trials and eventually help developing more appropriate treatments, we revised the present diagnostic criteria and made recommendations for some changes in the context of the 2nd Canadian Conference on the Development of Antidementia Therapies, held in 2004 and reviewed in the light of the recent literature as of early 2006. It is expected that in the near future, these dementia criteria for clinical trials will have to be revised again in order to include specific subtypes of the dementias as well as biomarkers, structural and functional imaging.

FMR1 alleles in Parkinson's disease: relation to cognitive decline and hallucinations, a longitudinal study

Carriers of expanded alleles of the fragile X mental retardation (FMR1) gene may display parkinsonism, cognitive decline, and behavioral changes. The authors screened 2 male groups of patients affected with Parkinson's disease (PD) (n = 137). One group (n = 56) was followed longitudinally for up to 12 years. Length of CGG repeats in PD patients was compared with healthy controls (n = 310). In addition, the association of the number of CGG repeats with cognitive decline or hallucinations was studied in the longitudinally followed PD group. The authors found no repeats in the premutation range (55-200 CGG repeats) and no significant difference in the proportion of intermediate-size (41-54 CGG repeats) carriers between the PD and the control groups. Using linear regression, the number of CGG repeats was not related to motor or cognitive progression. However, the marked cognitive decline in 2 patients carrying intermediate-size alleles points to a possible association. More studies with larger PD samples are warranted.

Evolution of cognitive dysfunction in an incident Parkinson's disease cohort

We have previously performed detailed clinical and neuropsychological assessments in a community-based cohort of patients with newly diagnosed parkinsonism, and through analysis of a subcohort with idiopathic Parkinson's disease (PD), we have demonstrated that cognitive dysfunction occurs even at the time of PD diagnosis and is heterogeneous. Longitudinal follow-up of the cohort has now been performed to examine the evolution of cognitive dysfunction within the early years of the disease. One hundred and eighty (79%) eligible patients from the original cohort with parkinsonism were available for re-assessment at between 3 and 5 years from their initial baseline assessments. PD diagnoses were re-validated with repeated application of the UKPDS Brain Bank criteria in order to maximize sensitivity and specificity, following which a diagnosis of idiopathic PD was confirmed in 126 patients. Thirteen out of 126 (10%) had developed dementia at a mean (SD) of 3.5 (0.7) years from diagnosis, corresponding to an annual dementia incidence of 30.0 (16.4-52.9) per 1000 person-years. A further 57% of PD patients showed evidence of cognitive impairment, with frontostriatal deficits being most common amongst the non-demented group. However, the most important clinical predictors of global cognitive decline following correction for age were neuropsychological tasks with a more posterior cortical basis, including semantic fluency and ability to copy an intersecting pentagons figure, as well as a non-tremor dominant motor phenotype at the baseline assessment. This work clarifies the profile of cognitive dysfunction in early PD and demonstrates that the dementing process in this illness is heralded by both postural and gait dysfunction and cognitive deficits with a posterior cortical basis, reflecting probable non-dopaminergic cortical Lewy body pathology. Furthermore, given that these predictors of dementia are readily measurable within just a few minutes in a clinical setting, our work may ultimately have practical implications in terms of guiding prognosis in individual patients.

Heterogeneity of cognitive dysfunction in Parkinson's disease: a cohort study

AIMS

The aim of this study was to examine the heterogeneity of cognitive dysfunction in Parkinson's disease (PD) and to evaluate the contribution of cognitive criteria to the diagnosis of dementia in PD.

METHODS

In a sample of 100 consecutive PD patients with motor fluctuations, an extensive neuropsychological test battery was administered. Each PD patient's cognitive profile was then compared with current cognitive criteria for dementia in PD.

RESULTS

Principal component analysis of the major test variables resulted in three components: one concerned with memory/attention, one with visuospatial, and one with executive/motor functions. Eighteen percent of our cohort showed no significant impairment on either domain. Fifty-one percent showed impairment in one cognitive domain, most frequently in the executive/motor component (88%). Twenty-four percent performed below normal on two cognitive components, most often executive/motor and memory/attention deficits (96%), and only 7% of our cohort had significant impairment on each derived cognitive component. Depending on the used criteria, 10-30% percent of our cohort could be categorized as PD patients with dementia.

CONCLUSIONS

Future guidelines for a uniform diagnosis of dementia in PD are needed for clinical use and therapeutic management.

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.

Long-term cognitive profile and incidence of dementia after STN-DBS in Parkinson's disease

An effect of subthalamic nucleus deep brain stimulation (STN-DBS) on cognition has been suspected but long-term observations are lacking. The aim of this study was to evaluate the long-term cognitive profile and the incidence of dementia in a cohort of Parkinson's disease (PD) patients treated by STN-DBS. 57 consecutive patients were prospectively assessed by the mean of a neuropsychological battery over 3 years after surgery. Dementia (DSM-IV) and UPDRS I to IV were recorded. 24.5% of patients converted to dementia over 3 years (incidence of 89 of 1,000 per year). This group of patients cognitively continuously worsened over 3 years up to fulfilling dementia criteria (PDD). The rest of the cohort remained cognitively stable (PD) over the whole follow-up. Preoperative differences between PDD and PD included older age (69.2 +/- 5.8 years; 62.6 +/- 8 years), presence of hallucinations and poorer executive score (10.1 +/- 5.9; 5.5 +/- 4.4). The incidence of dementia over 3 years after STN-DBS is similar to the one reported in medically treated patients. The PDD presented preoperative risk factors of developing dementia similar to those described in medically treated patients. These observations suggest dementia being secondary to the natural evolution of PD rather than a direct effect of STN-DBS.

Dementia syndromes: evaluation and treatment

As our population ages, diseases affecting memory and daily functioning will affect an increasing number of individuals, their families and the healthcare system. The social, financial and economic impacts will be profound. This article provides an overview of current dementia syndromes to assist clinicians in evaluating, educating and treating these patients.

A magnetic resonance imaging study of patients with Parkinson's disease with mild cognitive impairment and dementia using voxel-based morphometry

BACKGROUND

Dementia is common in Parkinson's disease, but the underlying brain pathology is not yet fully understood.

AIM

To examine the changes in the brain of patients with Parkinson's disease with mild cognitive impairment (MCI) and dementia, using structural magnetic resonance imaging.

METHODS

Using voxel-based morphometry, the grey matter atrophy on brain images of patients with Parkinson's disease and dementia (PDD; n = 16) and Parkinson's disease without dementia (PDND; n = 20), and healthy elderly subjects (n = 20) was studied. In the PDND group, 12 subjects had normal cognitive status and 8 had MCI. Standardised rating scales for motor, cognitive and psychiatric symptoms were used.

RESULTS

Widespread areas of cortical atrophy were found in patients with PDD compared with normal controls (in both temporal and frontal lobes and in the left parietal lobe). Grey matter reductions were found in frontal, parietal, limbic and temporal lobes in patients with PDD compared with those with PDND. In patients with PDND with MCI, areas of reduced grey matter in the left frontal and both temporal lobes were found.

CONCLUSION

These findings show that dementia in Parkinson's disease is associated with structural neocortical changes in the brain, and that cognitive impairment in patients with PDND may be associated with structural changes in the brain. Further studies with larger groups of patients are needed to confirm these findings.

Functional and Anatomical Magnetic Resonance Imaging in Parkinson’s Disease

For the past 15 years, measurements of cerebral blood flow as an indicator of neuronal activity have been used to gain a better understanding of the neural basis of motor and cognitive deficits in Parkinson's disease. The initial studies, using positron emission tomography, yielded results in keeping with the hypothesis that symptoms result from excessive cortical inhibition from cortico-striatal loops. However, subsequent studies with functional magnetic resonance imaging (fMRI) have shown that specific aspects of the paradigms used, such as the need to pay attention to one's movements, have a significant impact on activation patterns, which may complicate the interpretation of results. Functional neuroimaging has also been used to investigate the causes of cognitive impairment in Parkinson's disease. While some studies implicate dopamine loss in striatum, more recent investigations using anatomical MRI to measure cortical atrophy suggest that some cognitive deficits are attributable to direct cortical involvement by the disease.

The effect of age of onset of PD on risk of dementia

BACKGROUND

Dementia occurs in the majority of patients with Parkinson's disease (PD). Late onset of PD has been reported to be associated with a higher risk for dementia. However, age at onset (AAO) and age at baseline assessment are often correlated. The aim of this study was to explore whether AAO of PD symptoms is a risk factor for dementia independent of the general effect of age.

METHODS

Two community-based studies of PD in New York (n=281) and Rogaland county, Norway (n=227) and two population-based groups of healthy elderly from New York (n=180) and Odense, Denmark (n=2414) were followed prospectively for 3-4 years and assessed for dementia according to DSM-IIIR. All PD and control cases underwent neurological examination and were followed with neurological and neuropsychological assessments. We used Cox proportional hazards regression based on three different time scales to explore the effect of AAO of PD on risk of dementia, adjusting for age at baseline and other demographic and clinical variables.

FINDINGS

In both PD groups and in the pooled analyses, there was a significant effect of age at baseline assessment on the time to develop dementia, but there was no effect of AAO independent of age itself. Consistent with these results, there was no increased relative effect of age on the time to develop dementia in PD cases compared with controls.

INTERPRETATION

This study shows that it is the general effect of age, rather than AAO that is associated with incident dementia in subjects with PD.

Cognitive change in Parkinson disease

Parkinson disease (PD) is the most common neurodegenerative movement disorder, affecting 1 in 100 individuals over the age of 60. Dementia in the setting of PD (PDD) may be among the most debilitating symptoms associated with disease progression. Estimates of cognitive decline and dementia in PD suggest that up to 14% per year of patients over age 65 with PD will develop some cognitive impairment. Unfortunately, PDD is not well characterized and the relationship of PDD to Alzheimer disease remains unclear. PDD has been proposed as part of a spectrum with dementia with Lewy bodies, and PDD and dementia with Lewy bodies frequently coexist with Alzheimer disease. It is uncertain, however, whether there is a meaningful distinction between the different disorders. It has also been difficult to gain understanding of the interaction of motor and non-motor symptoms that affect quality of life in PD and confound cognitive and psychomotor performance. This review will examine the clinical, cognitive, neuropsychiatric features of cognitive deficits associated with PD, discuss their pathologic basis and propose avenues for future research.

Subtypes of mild cognitive impairment in Parkinson's disease: progression to dementia

The aim of this study was to establish the rate of progression from mild cognitive impairment (MCI) to dementia in patients with Parkinson's disease (PD). PD patients without dementia were recruited in 1997 from an ongoing prospective epidemiological study. The assessment included neurological and psychiatric examinations, a clinical interview based on the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R) criteria for dementia, and a battery of neuropsychological tests. PD was diagnosed according to established criteria, dementia was diagnosed according to the DSM-III-R criteria, and subtypes of MCI were classified according to modified Petersen's criteria. Seventy-two nondemented PD patients were included. A total of 34 were cognitively intact, whereas 38 were diagnosed with MCI (amnestic, n = 6; single nonmemory domain, n = 17; multiple domains slightly impaired, n = 15). Fifty-nine patients (82%) completed follow-up examination 4 years later, and 18 (62%) of the patients with MCI and 6 (20%) of the cognitively intact PD patients were demented (P = 0.001). Single domain nonmemory MCI and multiple domains slightly impaired MCI were associated with later development of dementia (P = 0.003; P = 0.04), whereas amnestic MCI subtype was not (P = 0.76). We conclude that patients with PD and MCI had a higher risk of developing dementia than cognitively intact PD patients, suggesting that MCI in PD is an early manifestation of dementia. However, these findings should be interpreted with caution due to the relatively small number of subjects included in this study.

Changes in motor subtype and risk for incident dementia in Parkinson's disease

The objective of this study was to assess the temporal relationship between changes in predominant motor symptoms and incident dementia in Parkinson's disease (PD). A community-based sample of 171 nondemented patients with PD was followed prospectively and examined at baseline and after 4 and 8 years. The motor subtype of Parkinsonism was classified into tremor-dominant (TD), indeterminate, or postural instability gait difficulty (PIGD) subtype at each visit, based on defined items in the Unified Parkinson's Disease Rating Scale, subscales II and III. Dementia was diagnosed according to DSM-III-R criteria, based on clinical interview, cognitive rating scales, and neuropsychological examination. Logistic regression was used to analyze the relationship between subtype of Parkinsonism and dementia. Transition from TD to PIGD subtype was associated with a more than threefold increase in the rate of Mini-Mental State Examination decline. Compared to patients with persistent TD or indeterminate subtype, the odds ratio for dementia was 56.7 (95% CI: 4.0-808.4; P = 0.003) for patients changing from TD or indeterminate subtype to PIGD subtype, and 80.0 (95% CI: 4.6-1400.1; P = 0.003) for patients with persistent PIGD subtype. Patients with TD subtype at baseline did not become demented until they developed PIGD subtype, and dementia did not occur among patients with persistent TD subtype of Parkinsonism. In a substantial proportion of PD patients who develop postural instability and gait disorder during the course of the disease, this transition is associated with accelerated cognitive decline and highly increased risk for subsequent dementia. These findings raise the question whether PIGD and dementia share common or parallel neuropathology.

Defining mild cognitive impairment in Parkinson's disease

Our purpose was to characterize a state of mild cognitive impairment (MCI) in Parkinson's disease (PD) (PD-MCI) that would be analogous to the MCI that is posited as a precursor of Alzheimer's disease (AD). We categorized 86 PD subjects in a brain bank population as either cognitively normal (PD-CogNL), PD-MCI using criteria that included a 1.5 standard deviation or greater deficit upon neuropsychological testing consistently across at least one cognitive domain without dementia, and PD dementia (PD-D) using DSM-IV criteria. Twenty-one percent of our PD sample met criteria for PD-MCI, 62% were PD-CogNL, and 17% had PD-D. The mean duration of PD and MMSE scores of the PD-MCI group were intermediate and significantly different from both PD-CogNL and PD-D. The cognitive domain most frequently abnormal in PD-MCI was frontal/executive dysfunction followed by amnestic deficit. Single domain PD-MCI was more common than PD-MCI involving multiple domains. We conclude that a stage of clinical cognitive impairment in PD exists between PD-CogNL and PD-D, and it may be defined by applying criteria similar to the MCI that is posited as a precursor of AD. Defining PD-MCI offers an opportunity for further study of cognitive impairment in PD and targets for earlier therapeutic intervention.

Smoking and cognitive function in Parkinson's disease

The risk of dementia among Parkinson's disease (PD) patients is greatly elevated compared to controls, yet little is known about determinants of cognitive function among PD patients. We assessed the relation between cigarette smoking prior to disease onset and later cognitive function among PD patients (n = 286) and age- and sex-matched controls (n = 1144) participating in the Nurses' Health Study and Health Professionals Follow-up Study. Both groups completed telephone-administered assessments of cognitive function. We used linear regression to calculate mean differences in cognitive test scores across smoking categories, adjusted for age, education, sex, age at onset of PD, and years since diagnosis. PD patients scored significantly worse on all tests than their matched controls. In analyses only among PD cases, but not among controls, current smokers at PD onset scored worse than never smokers on the Telephone Interview for Cognitive Status (difference = -0.82, 95% CI: -1.33, -0.30, P = 0.002) as well as on a global score combining results of all tests (difference = -0.36, 95% CI: -0.72, 0.01, P = 0.06). This difference was equivalent to the difference in global score observed among controls approximately 10 years apart in age. Analyses of pack-years of smoking prior to disease onset gave similar results. These findings, nested in prospective cohort studies, suggest that cigarette smoking prior to disease onset is associated with worse cognitive function in PD.

Regional cerebral blood flow in Parkinson??s disease as an indicator of cognitive impairment

OBJECTIVE

To investigate the pattern of regional cerebral blood flow (rCBF) deficits in Parkinson's disease patients in relation to cognitive decline and to assess the clinical usefulness of single photon emission tomography (SPET) scanning in differentiation between Parkinson's disease patients with dementia and those without cognitive deficits.

METHODS

We performed Tc-ECD SPET in 60 patients with idiopathic Parkinson's disease (F: 25, M: 35), with average age of 68.4 years (SD+/-7.3, range 51-81 years). All patients were examined neurologically with the assessment of stage and severity of Parkinson's disease (Hoehn-Yahr scale, UPDRS, Schwab-England scale). Detailed neuropsychological examination was performed in each Parkinson's disease patient. On the basis of DSM-IV criteria of dementia and the results obtained in psychological examination, the whole group was divided into three subgroups: I, with no cognitive changes (n = 17); II, with mild cognitive impairment (n = 25); and III, with dementia (n = 18).

RESULTS

There was noticeable significant decrease of perfusion in all areas in Parkinson's disease patients when compared to the age-matched control group of healthy volunteers (n = 20). In group III, perfusion was significantly decreased (when compared to groups I and II), particularly in parietal and temporal areas with the predominance of the left side. Regression analysis revealed two independent factors related to dementia: decrease of perfusion within left temporal lobe and its increase within left thalamus.

CONCLUSION

Parkinson's disease patients with dementia showed left temporo-parietal hypoperfusion as compared to a group of patients without dementia, which resembles perfusion deficits described in Alzheimer's disease. The hypoperfusion of the left temporal lobe with increase of rCBF within the left thalamus might be clinically useful in discrimination of Parkinson's disease patients with dementia against those without cognitive impairment.

Effect of levodopa on cognitive function in Parkinson's disease with and without dementia and dementia with Lewy bodies

BACKGROUND

Levodopa (L-dopa) is the gold standard treatment for Parkinson's disease, but a lack of clear efficacy combined with a perceived liability to neuropsychiatric side effects has limited L-dopa use in patients with parkinsonism and dementia. Therefore, the effect of L-dopa on the cognitive profile of dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD) is unclear.

AIM

To ascertain the acute and long-term effects of L-dopa on aspects of attention and cognition in patients with DLB and PDD, and to compare these with the effects in Parkinson's disease.

METHOD

Baseline cognitive and motor function was assessed off L-dopa in patients with Parkinson's disease (n = 22), PDD (n = 27) and DLB (n = 11) using standard "bedside" measures and a computerised programme detecting reaction times and accuracy. All patients then underwent an acute L-dopa challenge with subsequent subjective and objective analysis of alertness, verbal recall, reaction times and accuracy. The same parameters were measured after 3 months on L-dopa to assess the prolonged effect.

RESULTS

Acute L-dopa challenge considerably improved motor function and subjective alertness in all patients without compromising either reaction times or accuracy, but increased fluctuations were noted in both groups with dementia. Neuropsychiatric scores improved in patients with Parkinson's disease both with and without dementia on L-dopa at 3 months. Although patients with Parkinson's disease also had better mean global cognitive function at this time, mean verbal attention and memory deteriorated, and patients with PDD had slower reaction times in some tests. No patient had a marked deterioration over this time. Patients with DLB did not experience any adverse cognitive or neuropsychiatric effects after 3 months of L-dopa treatment.

CONCLUSION

The use of L-dopa in patients with parkinsonism with dementia does not adversely affect cognitive function.

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.

Beta-amlyoid 1-42 and tau-protein in cerebrospinal fluid of patients with Parkinson's disease dementia

Measurement of tau-protein and beta-amyloid(1-42 )(Abeta42) in cerebrospinal fluid (CSF) has gained increasing acceptance in the differential diagnosis of Alzheimer's disease. We investigated CSF tau-protein and Abeta42 concentrations in 73 patients with advanced idiopathic Parkinson's disease with dementia (PDD) and 23 patients with idiopathic Parkinson's disease without dementia (PD) and in a comparison group of 41 non-demented neurological patients (CG) using commercially available enzyme-linked-immunoabsorbant-assay (ELISA). tau-Protein levels were statistically significantly higher and Abeta42 lower in the PDD patients compared to PD patients and the CG. This observation was most marked (p < 0.05) in a subgroup of patients with PDD carrying the apolipoprotein genotype epsilon3/epsilon3. The distribution of the apolipoprotein genotypes in PDD and PD patients was similar to that of the CG. Although a significant difference in tau-protein values was observed between PDD and CG, no diagnostic cut-off value was established. These findings suggest that such protein CSF changes may help to support the clinical diagnosis of cognitive decline in PD and that there may be apolipoprotein-E-isoform-specific differences in CSF protein regulation in advanced PDD.

Provisional diagnostic criteria for depression in Parkinson's disease: report of an NINDS/NIMH Work Group

Mood disorders are the most common psychiatric problem associated with Parkinson's disease (PD), and have a negative impact on disability and quality of life. Accurate diagnosis of depressive disturbances in PD is critical and will facilitate the testing and use of new interventions; however, there are no clear diagnostic criteria for depressive disorders in PD. In their current form, strict Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria are difficult to use in PD and require attribution of specific symptoms to PD itself or the depressive syndrome. Additionally, DSM criteria for major depression and dysthymia exclude perhaps half of PD patients with comorbid clinically significant depression. This review summarizes an NIH-sponsored workshop and describes recommended changes to DSM diagnostic criteria for depression for use in PD. Participants also recommended: (1) an inclusive approach to symptom assessment to enhance reliability of ratings in PD and avoid the need to attribute symptoms to a particular cause; (2) the inclusion of subsyndromal depression in clinical research studies of depression of PD; (3) the specification of timing of assessments for PD patients with motor fluctuations; and (4) the use of informants for cognitively impaired patients. The proposed diagnostic criteria are provisional and intended to be defined further and validated but provide a common starting point for clinical research in PD-associated depression.

Visual rating of white matter hyperintensities in Parkinson's disease

Dementia is a common complication of Parkinson's disease (PD), but the cause is incompletely understood. In previous studies, dementia has been associated with an increase in hyperintense lesions in the cerebral white matter. The aim of this study was to explore whether white matter hyperintensities (WMH) on cerebral magnetic resonance imaging (MRI) are associated with dementia in PD. For this study, 35 patients with PD, 16 with dementia (PDD) and 19 without (PDND), and 20 control subjects were recruited. MRI scans of patients and controls were rated for WMH, blind to diagnosis, using the Scheltens visual rating scale. Both bivariate and multivariate statistical analyses were carried out. Cerebrovascular risk factors, education, gender, or age were similar across groups. Compared with the PDND group, the PDD group had significantly higher level of WMH in the deep white matter and in the periventricular areas. WMH in the deep white matter was the only variable that was associated significantly with Mini-Mental State Examination score and explained 38% of the variance in the multivariate linear regression analysis. Our findings suggest that WMH in the deep white matter may contribute to dementia in PD.

In vivo SPECT imaging of muscarinic acetylcholine receptors using (R,R) 123I-QNB in dementia with Lewy bodies and Parkinson's disease dementia

INTRODUCTION

Alterations in cholinergic function have been reported to be associated with dementia. The aim of this study was to investigate differences in the distribution of muscarinic acetylcholine receptors (mAChRs) using (R,R) 123I-iodo-quinuclidinyl-benzilate (QNB) and single photon emission computed tomography (SPECT) in dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD) and age-matched controls. 123I-QNB binding was also compared to the corresponding cerebral perfusion changes in the same subjects.

METHODS

63 subjects (24 controls, 14 DLB, 25 PDD) underwent 123I-QNB and perfusion 99mTc-exametazine SPECT scanning. Image analysis, using statistical parametric mapping (SPM99), involved spatial normalisation of each image to a customised template, followed by smoothing and intensity normalisation of each image to its corresponding mean whole brain uptake. Group effects and correlations were assessed using two sample t tests and linear regression respectively.

RESULTS

Relative to controls, significant elevation of 123I-QNB binding was apparent in the right occipital lobe in DLB and right and left occipital lobes in PDD (height threshold p<or=0.001 uncorrected). PDD also showed significant loss in uptake in frontal regions and temporal lobes bilaterally that was not present in DLB. These patterns appeared to be independent of any corresponding rCBF changes.

CONCLUSION

Significant elevation of mAChRs in the occipital lobe was associated with DLB and PDD. This may relate to the visual disturbances that are prevalent in these disorders. Further studies are required in order to establish the role of mAChRs in visual function.

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.

Interface between tauopathies and synucleinopathies: a tale of two proteins

Neurodegenerative diseases are often classified based on the abnormal accumulation of synuclein or tau. Traditionally, these disorders have been viewed as distinct clinical and pathological entities. However, advances in molecular genetics and protein biochemistry have shown intriguing overlaps. The most common synucleinopathy, Parkinson's disease, is characterized by extrapyramidal motor dysfunction, whereas the most common tauopathy, Alzheimer's disease, is defined by dementia. Yet there is overlap of clinical features; Parkinson's disease patients frequently have dementia, and Alzheimer's disease patients often manifest parkinsonism. Dementia with Lewy bodies exemplifies the existence of a continuum among these diseases. This overlap extends to the neuropathological findings; the pathognomonic hallmark for one set of disorders, Lewy bodies or neurofibrillary tangles, is present more often than expected in the other set. Moreover, mutations in LRRK2 known to cause parkinsonism are associated not only with dopaminergic neuronal degeneration, but also with the accumulation of synuclein, tau, neither, or both proteins. Other shared genetic features between tauopathies and synucleinopathies also exist. Finally, the known protein interactions between tau and synuclein further highlight the interface. Evidence for the intersection of tauopathies and synucleinopathies indicates the need for an updated disease classification scheme and may have important implications for therapeutic development.

Cholinesterase inhibitors for Parkinson's disease dementia

BACKGROUND

The loss of cholinergic, dopaminergic and noradrenergic innervations seen in Parkinson's Disease Dementia (PDD) suggest a potential role for cholinesterase inhibitors. Concerns have been expressed about a theoretical worsening of Parkinson's disease related symptoms particularly movement symptoms.

OBJECTIVES

To assess the efficacy, safety, tolerability and health economic data relating to the use of cholinesterase inhibitors in PDD.

SEARCH STRATEGY

The trials were identified from the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 19 April 2005 using the search term parkinson*This register contains records from major health care databases and many ongoing trial databases and is updated regularly.Comprehensive searches of abstracts from major scientific meetings were performed. Pharmaceutical companies were approached for information regarding additional and ongoing studies.

SELECTION CRITERIA

Randomized, double-blind, placebo-controlled studies assessing the effectiveness of cholinesterase inhibitors in PDD. Inclusion and exclusion criteria were stated to limit bias.

DATA COLLECTION AND ANALYSIS

Two reviewers (IM, CF) independently reviewed the quality of the studies utilising criteria from the Cochrane Collaboration Handbook. Medications were examined separately and as a group. The outcome measures assessed were in the following domains: neuropsychiatric features, cognition, global impression, daily living activities, quality of life, burden on caregiver, Parkinsonian related symptoms, treatment acceptability as determined by withdrawal from trials, safety as determined by the frequency of adverse events, institutionalisation, death and health economic factors.

MAIN RESULTS

A detailed and systematic search of relevant databases identified one published randomized, double-blind, placebo-controlled study (Emre 2004) involving 541 patients that compared rivastigmine with placebo. Rivastigmine produced statistically significant improvements in several outcome measures. On the primary cognitive measure, the ADAS-Cog, rivastigmine was associated with a 2.80 point ADAS-Cog improvement [WMD -2.80, 95% Cl -4.26 to -1.34, P = 0.0002] and a 2.50 point ADCS-ADL improvement [95% Cl 0.43 to 4.57, P = 0.02] relative to placebo. Clinically meaningful (moderate or marked) improvement occurred in 5.3% more patients on rivastigmine, and meaningful worsening occurred in 10.1% more patients on placebo. Tolerability appeared to be a significant issue. Significantly more patients on rivastigmine dropped out of the study due to adverse events [62/362 versus 14/179, OR 2.44, 95% Cl 1.32 to 4.48, P = 0.004]. Nausea [20/179 versus 105/362, OR 3.25, 95% Cl 1.94 to 5.45, P < 0.00001], tremor [7/179 versus 37/362, OR 2.80, 95% Cl 1.22 to 6.41, P = 0.01] and in particular vomiting [3/179 versus 60/362, OR 11.66, 95% Cl 3.60 to 37.72, P < 0.0001] were significantly more common with rivastigmine. However, significantly fewer patients died on rivastigmine than placebo [4/362 versus 7/179, OR 0.27, 95% CI 0.08 to 0.95, P = 0.04]

AUTHORS' CONCLUSIONS

Rivastigmine appears to improve cognition and activities of daily living in patients with PDD. This results in clinically meaningful benefit in about 15% of cases. There is a need for more studies utilising pragmatic measures such as time to residential care facility and both patient and carer quality of life assessments. Future trials should involve other cholinesterase inhibitors, utilise tools to analyse the data that limit any bias and measure health economic factors. It is unlikely that relying solely on the last observation carried forward (LOCF) is sufficient. Publication of the observed case data in the largest trial would assist (Emre 2004). Adverse events were associated with the cholinergic activity of rivastigmine, but may limit patient acceptability as evidenced by the high drop out rate in the active arm.

The diagnosis of Parkinson's disease

The correct diagnosis of Parkinson's disease is important for prognostic and therapeutic reasons and is essential for clinical research. Investigations of the diagnostic accuracy for the disease and other forms of parkinsonism in community-based samples of patients taking antiparkinsonian medication confirmed a diagnosis of parkinsonism in only 74% of patients and clinically probable Parkinson's disease in 53% of patients. Clinicopathological studies based on brain bank material from the UK and Canada have shown that clinicians diagnose the disease incorrectly in about 25% of patients. In these studies, the most common reasons for misdiagnosis were presence of essential tremor, vascular parkinsonism, and atypical parkinsonian syndromes. Infrequent diagnostic errors included Alzheimer's disease, dementia with Lewy bodies, and drug-induced parkinsonism. Increasing knowledge of the heterogeneous clinical presentation of the various parkinsonisms has resulted in improved diagnostic accuracy of the various parkinsonian syndromes in specialised movement-disorder units. Also genetic testing and various other ancillary tests, such as olfactory testing, MRI, and dopamine-transporter single-photon-emission computed-tomography imaging, help with clinical diagnostic decisions.