Increased cortico-cortical functional connectivity in early-stage Parkinson's disease: an MEG study

We set out to determine whether changes in resting-state cortico-cortical functional connectivity are a feature of early-stage Parkinson's disease (PD), explore how functional coupling might evolve over the course of the disease and establish its relationship with clinical deficits. Whole-head magnetoencephalography was performed in an eyes-closed resting-state condition in 70 PD patients with varying disease duration (including 18 recently diagnosed, drug-naive patients) in an "OFF" medication state and 21 controls. Neuropsychological testing was performed in all subjects. Data analysis involved calculation of three synchronization likelihood (SL, a general measure of linear and non-linear temporal correlations between time series) measures which reflect functional connectivity within (local) and between (intrahemispheric and interhemispheric) ten major cortical regions in five frequency bands. Recently diagnosed, drug-naive patients showed an overall increase in alpha1 SL relative to controls. Cross-sectional analysis in all patients revealed that disease duration was positively associated with alpha2 and beta SL measures, while severity of parkinsonism was positively associated with theta and beta SL measures. Moderately advanced patients had increases in theta, alpha1, alpha2 and beta SL, particularly with regard to local SL. In recently diagnosed patients, cognitive perseveration was associated with increased interhemispheric alpha1 SL. Increased resting-state cortico-cortical functional connectivity in the 8-10 Hz alpha range is a feature of PD from the earliest clinical stages onward. With disease progression, neighboring frequency bands become increasingly involved. These findings suggest that changes in functional coupling over the course of PD may be linked to the topographical progression of pathology over the brain.

First case of ataxia with isolated vitamin E deficiency in the Netherlands

We present a 36-year-old Dutch woman who suffered from a progressive form of cerebellar ataxia since school age. In her childhood she was diagnosed with Friedreich's ataxia. Genetic analysis of the frataxin gene at 34 years of age, however, had revealed no abnormal GAA triplet expansion. We identified two point mutations in the alpha-tocopherol transport protein (alpha-TTP) gene on chromosome 8q13, and the diagnosis ataxia with isolated vitamin E deficiency (AVED) was made. This report illustrates the diagnosis AVED and its relation to vitamin E metabolism. It is important to evaluate previously made diagnoses when newly developed tests can be performed for confirmation.

Slowing of oscillatory brain activity is a stable characteristic of Parkinson's disease without dementia

Extensive changes in resting-state oscillatory brain activity have recently been demonstrated using magnetoencephalography (MEG) in moderately advanced, non-demented Parkinson's disease patients relative to age-matched controls. The aim of the present study was to determine the onset and evolution of these changes over the disease course and their relationship with clinical parameters. In addition, we evaluated the effects of dopaminomimetics on resting-state oscillatory brain activity in levodopa-treated patients. MEG background oscillatory activity was studied in a group of 70 Parkinson's disease patients with varying disease duration and severity (including 18 de novo patients) as well as in 21 controls that were age-matched to the de novo patients. Whole head 151-channel MEG recordings were obtained in an eyes-closed resting-state condition. Levodopa-treated patients (N = 37) were examined both in a practically defined 'OFF' as well as in the 'ON' state. Relative spectral power was calculated for delta, theta, low alpha, high alpha, beta and gamma frequency bands and averaged for 10 cortical regions of interest (ROIs). Additionally, extensive clinical and neuropsychological testing was performed in all subjects. De novo Parkinson's disease patients showed widespread slowing of background MEG activity relative to controls. Changes included a widespread increase in theta and low alpha power, as well as a loss of beta power over all but the frontal ROIs and a loss of gamma power over all but the right occipital ROI. Neuropsychological assessment revealed abnormal perseveration in de novo patients, which was associated with increased low alpha power in centroparietal ROIs. In the whole group of Parkinson's disease patients, longer disease duration was associated with reduced low alpha power in the right temporal and right occipital ROI, but not with any other spectral power measure. No association was found between spectral power and disease stage, disease severity or dose of dopaminomimetics. In patients on levodopa therapy, a change from the 'OFF' to the 'ON' state was associated with decreases in right frontal theta, left occipital beta and left temporal gamma power and an increase in right parietal gamma power. Widespread slowing of oscillatory brain activity is a characteristic of non-demented Parkinson's disease patients from the earliest clinical stages onwards that is (largely) independent of disease duration, stage and severity and hardly influenced by dopaminomimetic treatment. Some early cognitive deficits in Parkinson's disease appear to be associated with increased low alpha power. We postulate a role for hypofunctional non-dopaminergic ascending neurotransmitter systems in spectral power changes in non-demented Parkinson's disease patients.

Resting state oscillatory brain dynamics in Parkinson’s disease: An MEG study

OBJECTIVE

The pathophysiological mechanisms of cognitive dysfunction and dementia in Parkinson's disease (PD) are still poorly understood. Altered resting state oscillatory brain activity may reflect underlying neuropathological changes. The present study using magneto encephalography (MEG) was set up to study differences in the pattern of resting state oscillatory brain activity in groups of demented and non-demented PD patients and healthy, elderly controls.

METHODS

The pattern of MEG background oscillatory activity was studied in 13 demented PD patients, 13 non-demented PD patients and 13 healthy controls. Whole head MEG recordings were obtained in the morning in an eyes closed and an eyes open, resting state condition. Relative spectral power was calculated using Fast Fourier Transformation in delta, theta, alpha, beta and gamma frequency bands.

RESULTS

In the non-demented PD patients, relative theta power was diffusely increased and beta power concomitantly decreased relative to controls. gamma Power was decreased in central and parietal channels. In the demented PD patients, a diffuse increase in relative delta and to lesser extent theta power and a decrease in relative alpha, beta and to lesser extent gamma power were found in comparison to the non-demented PD group. In addition, reactivity to eye opening was much reduced in the demented PD group.

CONCLUSIONS

Parkinson's disease is characterized by a slowing of resting state brain activity involving theta, beta and gamma frequency bands. Dementia in PD is associated with a further slowing of resting state brain activity, additionally involving delta and alpha bands, as well as a reduction in reactivity to eye-opening.

SIGNIFICANCE

The differential patterns of slowing of resting state brain activity in demented and non-demented PD patients suggests that, in conjunction with a progression of the pathological changes already present in non-demented patients, additional mechanisms are involved in the development of dementia in PD.

Parkinson's disease: premotor clinico-pathological correlations

Parkinsonism is a clinical syndrome characterized by bradykinesia, hypo-/ akinesia, muscular rigidity, and resting tremor, mainly caused by Parkinson's disease (PD). Progressive loss of nigral neurons with Lewy bodies is considered an essential neuropathological feature. Recent studies, however, indicate that nigral degeneration is only a part of this synucleinopathy, and clinical symptoms go far beyond motor parkinsonism. Olfactory disturbances, autonomic dysfunction, pain, sleep fragmentation, depression, and dementia with or without psychosis are frequently seen. The variability in the expression of these signs and symptoms suggests multiple causes and/or pathogeneses within the present diagnostic disease entity. In this article, a recently proposed staging of PD-related brain pathology will be correlated with the various clinical expressions. It will be argued that the specific topographical sequence of the pathology, depending on the extent and progression of the degenerative process at defined sites, may explain the individually variable expression of this disease.

PD-related psychosis: pathophysiology with therapeutical strategies

Parkinson's disease (PD) is a chronic, neurodegenerative disease with degeneration of the central dopaminergic neurons in the substantia nigra, leading to a depletion of dopamine (DA) in the striatum. This depletion causes the clinical hallmarks of this disease: bradykinesia, hypokinesia, rigidity, tremor and postural instability. Besides these well known motor symptoms, non-motor symptoms may develop, such as hyposmia, sleep disorders, autonomic disturbances, depression, cognitive impairment and psychosis. Pathophysiological mechanisms underlying these symptoms not only comprise Lewy body pathology in the central dopaminergic system, but also in the noradrenergic, serotinergic and cholinergic transmittersystems. Indeed, in Parkinson's disease, about 30-40% of the patients suffers fluctuating psychotic symptoms, mainly paranoid delusions and/or visual or acoustic hallucinations, symptoms considered to represent major contributors to patient and caregiver distress and nursing home placement. Endogenous (related to the disease process itself) as well as exogenous (related to therapeutical interventions) psychotogenic factors may contribute to the development of psychotic symptoms in PD. Therapeutical strategies, therefore, are aimed to reduce both endogenous and exogenous factors. To reduce endogenous psychotogenic factors, cholinesterase inhibitors, suggested to reduce cognitive deterioration, now seem to be the drugs of choice. In exogenously induced psychotic symptoms, atypical antipsychotics are considered the most effective. However, as psychotic symptoms in PD are often influenced by both endogenous and exogenous factors, a combination of both strategies may be preferred.

Disease-related and drug-induced changes in dopamine transporter expression might undermine the reliability of imaging studies of disease progression in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Standard therapeutic interventions are aimed at replenishment of empty dopamine stores with levodopa or substitution with dopamine receptor agonists. However, in the long term this symptomatic therapy fails. Currently, various neuroprotective agents are being developed, with the intention to slow down the degeneration of dopaminergic neurons. In this context, the early identification of persons at risk to develop the disease as well as the assessment of the effectiveness of putative neuroprotective agents, are critical issues. Dopamine transporter (DAT) scintigraphy with single photon emission computed tomography (SPECT) has been used to assess the dopaminergic function in PD. Initial studies with several radioligands show significant loss of DAT binding in PD patients as compared to controls. In this paper we review the evidence on the utility of DAT imaging with SPECT in early PD detection as well as in monitoring neurprotection.

Clinical and genetic evaluation of 8 Polish families with levodopa-responsive parkinsonism

We studied 8 large Polish families with parkinsonism, 6 of which were newly identified. Thirty-six family members had well-documented levodopa-responsive parkinsonism. The phenotype of affected individuals was indistinguishable from that of persons with idiopathic Parkinson disease (PD). The pattern of inheritance in 5 families was consistent with autosomal dominant transmission; in 3 families the mode of inheritance was uncertain. Single photon emission computed tomography (SPECT) studies with the dopamine transporter radioligand [(123)I]FP-CIT were performed in 1 family. The SPECT study showed striatal presynaptic dopaminergic degeneration consistent with sporadic PD in 1 affected family member and no signs of nigrostriatal dopaminergic dysfunction in 5 at-risk individuals. Sequence analysis in all 8 families excluded known genes associated with familial parkinsonism. Genome-wide 2-point linkage studies in the largest 2 families did not identify significant linkage (z > 3.0), although positive scores were obtained for 5q23 (D5S1462 and D5S2501), a locus previously implicated in disease susceptibility.

Cognitive dysfunction and dementia in Parkinson?s disease

Parkinson's disease (PD) is a slowly progressive neurodegenerative disorder mainly characterized by degeneration of dopaminergic neurons in the substantia nigra and the ventral tegmental area, in combination with a varying loss of central noradrenergic (locus coeruleus), cholinergic (nucleus basalis of Meynert) and serotonergic (dorsal raphe nuclei) integrity, leading to a multitude of motor and non-motor behavioral disturbances. Apart from the clinical motor hallmarks, in the early stages of disease, subtle cognitive dysfunction might be seen comprising mainly executive dysfunction, with secondary visuospatial and mnemonic disturbances. In about 20-40% of patients, these problems may eventually proceed to dementia, which constitutes an important risk factor for caregiver distress, decreased quality of life and nursing home placement. Dementia in PD is typically characterized by a progressive dysexecutive syndrome with attentional deficits and fluctuating cognition, often accompanied by psychotic symptoms. It is thought to be the result of a combination of both subcortical and cortical changes. PD-related dopaminergic deficiency in the nucleus caudatus and mesocortical areas (due to degeneration of projections from the substantia nigra and ventral tegmental area) and cholinergic deficiency in the cortex (due to degeneration of ascending projections from the nucleus basalis of Meynert), combined with additional Alzheimer-pathology and cortical Lewy bodies, may greatly contribute to dementia. Current treatment of dementia in PD is based on compensation of the profound cholinergic deficiency. Recent studies with the cholinesterase inhibitors galantamine, donepezil and rivastigmine show promising results in improving cognition and ameliorating psychotic symptoms, which must further be confirmed in randomized controlled trials.

Psychotic symptoms in Parkinson's disease: pathophysiology and management

Parkinson's disease (PD) is a chronic neurodegenerative disease, in which mainly dopaminergic neurons in the substantia nigra in the brain degenerate, leading to a depletion of dopamine (DA) in the striatum. The most important motor disturbances of the disease are bradykinesia (slowing down of movement), hypokinesia (poverty of movement), rigidity (muscle stiffness), tremor and postural instability. Besides these well-known motor symptoms, non-motor symptoms may develop, such as depression, cognitive impairment and psychosis. Psychotic symptoms constitute a relatively common but nevertheless serious complication, with visual hallucinations and paranoid delusions often being most prominent. These symptoms are important contributors to patient and caregiver distress and are often important risk factors for nursing home placement. Exogenous (related to therapeutic interventions) factors are of major importance but endogenous (related to the disease process itself) factors might also contribute to the development of psychotic symptoms in PD. Therapeutic strategies comprise reduction of antiparkinsonian treatment, cholinesterase inhibitors and atypical antipsychotics. As psychotic symptoms in PD are often influenced by both endogenous and exogenous factors, a combination of strategies may be chosen.

Deficits on Corsi's block-tapping task in early stage Parkinson's disease

Cognitive deficits in Parkinson's disease (PD) include disturbances in working memory. We examined sequential visuo-spatial memory span by means of an adaptation of the Corsi Block-Tapping Task in groups of medicated (n=14) and non-medicated (n=15) patients with early stage PD, and in control subjects (n=22). A deficit in memory span was found in medicated patients with early stage PD relative to controls. There were no differences between non-medicated patients relative to either controls or medicated patients. A decrease in sequential visuo-spatial memory span appears to be a relatively early feature of PD and most likely reflects executive rather than mnemonic dysfunction.

The role of acetylcholine and dopamine in dementia and psychosis in Parkinson's disease

Parkinson's disease (PD) is a progressive neurological disorder in which there is abnormal degeneration of dopaminergic neurons in the substantia nigra and the ventral tegmental area combined with a varying degree of deterioration of the cholinergic, serotonergic and noradrenergic system, leading to a variety of motor and non-motor abnormalities. Dopamine (DA) depletion in nigrostriatal projections manifests with abnormal spontaneous motor behavior and (subtle) cognitive deficits, whereas more overt cognitive impairment may develop with concomitant DA-deficiency related mesocorticolimbic denervation. In combination with a progressive dysfunction of the ascending neocortical cholinergic (and serotonergic and noradrenergic) projections, mainly due to a loss of cholinergic neurons in the nucleus basalis of Meynert (NbM), these cognitive deficits may proceed into dementia sometimes in combination with psychotic behavior, which might also be associated with dopaminomimetic and/or anticholinergic treatment as well as with cholinergic deficit or dopaminomimetic induced REM sleep disturbances. As these psychiatric symptoms have a substantial negative effect on the patient's quality of life, contribute to caregiver distress and are predictive of nursing home placement, identification and adequate treatment is of great importance. Recent evidence supports a possible role for cholinomimetic therapy in alleviating cognitive dysfunction and psychotic symptoms in PD.

[(123)I]beta-CIT SPECT is a useful method for monitoring dopaminergic degeneration in early stage Parkinson's disease

OBJECTIVES

To examine the validity of [(123)I]beta-CIT SPECT for monitoring the progression of dopaminergic degeneration in Parkinson's disease; to investigate the influence of short term treatment with D(2)receptor agonists on striatal [(123)I]beta-CIT binding; and to determine the sample size and frequency of SPECT imaging required to demonstrate a significant effect of a putative neuroprotective agent.

METHODS

A group of 50 early stage Parkinson's disease patients was examined. Two SPECT imaging series were obtained, 12 months apart. The mean annual change in the ratio of specific to non-specific [(123)I]beta-CIT binding to the striatum, putamen, and caudate nucleus was used as the outcome measure.

RESULTS

A decrease in [(123)I]beta-CIT binding ratios between the two images was found in all regions of interest. The average decrease in [(123)I]beta-CIT binding ratios was about 8% in the whole striatum, 8% in the putaminal region, and 4% in the caudate region. Comparison of scans done in nine patients under two different conditions-in the off state and while on drug treatment-showed no significant alterations in the expression of striatal dopamine transporters as measured using [(123)I]beta-CIT SPECT. Power analysis indicated that to detect a significant (p < 0.05) effect of a neuroprotective agent with 0.80 power and 30% of predicted protection within two years, 216 patients are required in each group when the effects are measured in the whole putamen.

CONCLUSIONS

[(123)I]beta-CIT SPECT seems to be a useful tool to investigate the progression of dopaminergic degeneration in Parkinson's disease and may provide an objective method of measuring the effectiveness of neuroprotective treatments. Short term treatment with a D(2)agonist does not have a significant influence on [(123)I]beta-CIT binding to dopamine transporters. If the latter finding is replicated in larger groups of patients, it supports the suitability of [(123)I]beta-CIT SPECT for examining the progression of neurodegeneration in patients being treated with D(2)receptor agonists.

The influence of computer experience on visuo-motor control: implications for visuo-motor testing in Parkinson's disease

Abnormalities in visuo-motor control have repeatedly been reported in Parkinson's disease (PD) patients. In the more recent studies, tasks measuring visuo-motor performance are usually computerised tasks requiring the use of a mouse-like manipulandum. In healthy subjects, previous computer mouse experience can influence performance in computerised visuo-motor tasks. We, therefore, investigated the potential confounding effect of mouse experience in a visuo-motor task used in PD patients, the visuo-motor testing (VMT) system, and its concurrent usefulness in the diagnosis of PD. Our study population included 49 early PD patients and 31 controls. The VMT system involves moving a pointer over a sinusoidal path displayed on a computer screen by moving an unseen digitiser mouse over a tablet. In both PD patients and controls, subjects with low mouse experience scored worse than subjects with high mouse experience on variables measuring movement accuracy, direction and speed. After correction for mouse experience the aforementioned deficits were still present in PD patients with low mouse experience. However, PD patients with high mouse experience only showed deficits in movement accuracy. It would seem that previous mouse experience can at least partly compensate for deficits in directional control and speed in PD patients, implying a possible role for training in the treatment of functional motor impairments in PD. Future studies using computerised psychomotor tasks should take sufficient precautions to avoid potential confounding effects of mouse experience. The present data further suggest that only accuracy of visuo-motor control might be a useful parameter in the (early) diagnosis of PD.

[123I]FP-CIT SPECT is a useful method to monitor the rate of dopaminergic degeneration in early-stage Parkinson's disease

We investigated the applicability [123I]FP-CIT SPECT for the assessment of the rate of dopaminergic degeneration in PD. Twenty early-stage PD patients (age range 43-73 yr; mean age 55.4) were examined twice, a mean of 12 months apart. The mean annual change in the ratio of specific to nonspecific [123I]FP-CIT binding to the striatum was used as the outcome measure. The mean annual decrease in striatal [123I]FP-CIT binding ratios was found to be about 8% (of the baseline mean). In order to demonstrate a significant effect (p < 0.05) of putative neuroprotective agent with 0.80 power and 50% of predicted protection within 2 years, 36 patients are required in each group, when the effects are measured by means of changes in [123I]FP-CIT binding ratios in whole striatum. Our findings indicate that [123I]FP-CIT SPECT seems to be a useful tool to investigate the progression of dopaminergic degeneration in PD and may provide an objective method of measuring the effectiveness of neuroprotective therapies.

[Presymptomatic detection of Parkinson's disease]

Parkinson's disease (PD) is characterized by a progressive degeneration of mesencephalic dopaminergic neurons. More than half of these neurons are lost in a presymptomatic phase of an estimated 4-6 years duration. It is obvious that any type of treatment aimed at slowing down the disease process should preferably be applied in this presymptomatic phase. Presymptomatic detection of PD has therefore become an important goal. In a recent study in a population of 361 asymptomatic first degree relatives of PD patients, we were able to demonstrate that presymptomatic detection is possible by means of a combination of three olfactory processing tasks and [123l] beta-CIT single photon emission computed tomography (SPECT) scanning of the nigrostriatal dopaminergic system. These results are a first step towards the development of a screening strategy that may be applied in the general population. Impairments of olfactory function, however, are not specific to PD but are also associated with other neurodegenerative disorders (e.g. Alzheimer's disease) and certain lifestyle characteristics (e.g. smoking). In the next few years our research efforts will focus on two different approaches to develop a more specific screening strategy. First, olfactory processing tasks will be combined with tasks aimed at detecting subtle (visuo)motor disturbances and early cognitive impairments. In parallel, an effort will be made to define disease-specific patterns of olfactory dysfunction in neurodegenerative disorders.

Motor perseveration is an early sign of Parkinson's disease

Perseveration in the generation of random motor behavior was examined by means of the Vienna perseverance task in groups of de novo (n = 18) and treated (n = 18) patients with early PD, and in control subjects (n = 18). In comparison with control subjects, both the de novo and treated patients with PD were relatively unable to generate random motor sequences, indicating a decreased ability to switch cortical behavioral programs in PD. An impairment of random motor generation appears to be a very early feature of PD.

Rigidity decreases resting tremor intensity in Parkinson's disease: A [(123)I]beta-CIT SPECT study in early, nonmedicated patients

Tremor is one of the clinical hallmarks of Parkinson's disease (PD). Although it is accepted that other classic symptoms of PD such as rigidity and bradykinesia result from a degeneration of the nigrostriatal system and subsequent reduction in striatal dopamine, the pathophysiology of resting tremor remains unclear. The majority of recent single photon emission computed tomography (SPECT) and positron emission tomography (PET) studies, using various radioligands, demonstrated significant correlation between striatal radioligand bindings and the degree of parkinsonian symptoms such as rigidity and bradykinesia, but not tremor. We investigate the relationship between the degeneration of the nigrostriatal pathway and the appearance of resting tremor, taking into account the possible interference of rigidity with the resting tremor. Thirty early and drug-naïve PD patients were examined. Tremor and rigidity of the arms were assessed using UPDRS, and the power of tremor was estimated using spectral analysis of tremor peaks. [(123)I]beta-CIT SPECT was used to assess degeneration of the dopaminergic system in PD patients. A comparison between asymmetry indices showed that in terms of both tremor and rigidity, the most affected arm corresponded significantly with the contralateral striatum, having the largest reduction in radioligand binding. Furthermore, tremor power accounted for a significant part of variance in the contralateral striatum, suggesting a relationship between this PD symptom and the degeneration of the dopaminergic system. Further, the degree of tremor was reduced with increasing rigidity. However, correcting for the influence of rigidity, the significant contribution of tremor in the variance in the contralateral striatal [(123)I]beta-CIT binding disappeared. When the confounding influence of rigidity is taken into account, no significant direct relationship between dopaminergic degeneration and the degree of tremor could be found. Other pathophysiological mechanisms should be similarly investigated in order to further our understanding of the origin of resting tremor in PD.

Intrinsic and extrinsic psychosis in Parkinson's disease

Direct and indirect signs and symptoms of Parkinson's disease are a major cause of disability in the elderly. Intrinsic symptoms comprise not only the well-known clinical hallmarks of this disease with motor behavioral abnormalities, such as bradykinesia, hypokinesia, rigidity and tremor, but also autonomic failure with orthostatic hypotension, urinal incontinence and impotence as well as non-motor behavioral abnormalities: mental dysfunction characterized by mood disorders, cognitive dysfunction and, sporadically, delusions and hallucinations. These symptoms are caused by a progressive abnormal degeneration of the dopamine (DA) producing cells in the substantia nigra (SN) and ventral tegmentum area (VTA) in combination with an interindividual fluctuating degree of decay in the noradrenergic (locus coeruleus), cholinergic forebrain (nucleus basalis of Meynert) and serotoninergic (dorsal raphe nuclei) systems. Extrinsic symptoms, induced by pharmacotherapy, mainly manifest with (un)predictable motor response fluctuations and dopaminomimetic psychosis. Psychological and psychiatric symptoms in Parkinson's disease (PD) are important predictors of the patient's quality of life. As these symptoms are potentially treatable, identification is of major clinical importance both for the patients and their caregivers and may enable to maintain Parkinson's disease patients at home for a longer period.

Management of psychosis in Parkinson's disease

Psychosis is quite common in Parkinson's disease (approximately 25% of patients) and therefore constitutes a serious public health problem. All patients suffering from idiopathic Parkinson's disease, and especially elderly and demented patients, are at risk of developing delusions or hallucinations. The most prominent psychotogenic factors are dopaminomimetic agents, which may induce dopamine hypersensitivity in the frontal and limbic dopamine projection regions, and consequently, either directly or indirectly, elicit psychotic signs and symptoms. A Parkinson's disease-related cholinergic deficit in combination with an age-related further loss of cholinergic integrity also plays a prominent role. Psychosis in Parkinson's disease patients appears to be a more important contributor to caregiver distress than motor parkinsonism. Psychosis therefore probably represents the single greatest risk factor for nursing home placement. Typical antipsychotic drugs, because of their selective dopamine receptor antagonistic effects, can reduce psychotic signs but at the cost of an increase in parkinsonism. As a consequence of a non-selective antagonism at both serotonergic and dopaminergic receptors, atypical antipsychotic drugs are associated with fewer extrapyramidal side-effects. On the other hand, hypersensitivity to these agents may induce delirium or a malignant neuroleptic syndrome. Atypical antipsychotic agents such as clozapine, quetiapine and olanzapine should therefore be started at very low doses that are increased gradually. Cholinomimetic therapy may prove to be helpful in the prevention and treatment of psychotic manifestations in Parkinson's disease patients, given the effects observed in patients suffering from dementia with Lewy bodies.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17): PPND family. A longitudinal videotape demonstration

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), characterized by an autosomal dominant inheritance pattern, has recently been recognized as a distinct entity that can display a confusingly broad clinical phenotype. The pallido-ponto-nigral degeneration (PPND) variant is the prototypical example of the parkinsonism-predominant pattern of FTDP-17. A longitudinal videotape demonstration of the clinical progression of this entity in a single individual, along with brief videotape segments from three additional affected individuals, is presented in order to facilitate recognition of this disorder.

Subclinical dopaminergic dysfunction in asymptomatic Parkinson's disease patients' relatives with a decreased sense of smell

By the time a clinical diagnosis of Parkinson's disease (PD) is made, a significant loss of dopaminergic neurons has already occurred. Identifying patients in the period between the presumed onset of dopaminergic cell loss and the appearance of clinical parkinsonism may be of major importance in the development of effective neuroprotective treatment strategies. In an effort to develop a feasible strategy to detect preclinical PD, a combination of olfactory processing tasks, including odor detection, odor identification, and odor discrimination was used to select groups of hyposmic and normosmic individuals from a total of 250 relatives (parents, siblings, or children) of subjects with PD. Single photon emission computed tomography (SPECT) with [123I]beta-CIT as a dopamine transporter ligand was used to assess nigrostriatal dopaminergic function in 25 hyposmic and 23 normosmic relatives of PD patients. An abnormal reduction in striatal dopamine transporter binding was found in 4 out of 25 hyposmic relatives of PD patients, two of whom subsequently developed clinical parkinsonism, and in none of the 23 normosmic relatives. These observations demonstrate that subclinical reductions in dopamine transporter binding can be detected in asymptomatic relatives of sporadic PD patients by means of [123I]beta-CIT and SPECT. The results further indicate that olfactory deficits may precede clinical motor signs in PD.

The clinical benefit of imaging striatal dopamine transporters with [123I]FP-CIT SPET in differentiating patients with presynaptic parkinsonism from those with other forms of parkinsonism

[123I]FP-CIT (N-omega-fluoropropyl-2 beta-carbomethoxy-3 beta-(4-iodophenyl)nortropane) has been developed successfully as a radioligand for single-photon emission tomography (SPET) imaging of dopamine transporters, which are situated in the membrane of dopaminergic neurons. Imaging of these transporters has shown promise as a clinical tool to detect degeneration of the dopaminergic nigrostriatal pathway. Several "presynaptic parkinsonian" syndromes, such as Parkinson's disease or multiple system atrophy, are characterised by degeneration of the nigrostriatal pathway. [123I]FP-CIT SPET imaging studies have shown the ability to detect loss of striatal dopamine transporters in such syndromes. However, in clinical practice it is sometimes difficult, but important, to discriminate patients with "presynaptic parkinsonism" from those with other forms of parkinsonism not characterised by loss of presynaptic dopaminergic cells (e.g. psychogenic parkinsonism or drug-induced postsynaptic parkinsonism). In these inconclusive cases, it may be of value to confirm or exclude the existence of degeneration of nigrostriatal dopaminergic cells by using imaging techniques such as [123I]FP-CIT SPET. Using [123I]FP-CIT SPET, we have imaged the striatal dopamine transporters in a group of patients with inconclusive forms of parkinsonism, and, moreover, have been able to perform clinical follow-up of these patients 2-4 years after imaging. In 33 inconclusive cases, ratios of specific to non-specific binding were calculated for the caudate nucleus and putamen following [123I]FP-CIT SPET imaging and compared with ratios obtained in healthy controls. In nine of the patients, degeneration of the nigrostriatal pathway was found scintigraphically and in all these cases, presynaptic parkinsonism was confirmed by clinical follow-up. In the other 24 subjects no degeneration was found scintigraphically. Forms of parkinsonism other than the presynaptic were confirmed at follow-up in 19 cases, and in three cases no conclusive diagnosis was established, but presynaptic parkinsonism was excluded clinically. A clinical diagnosis of presynaptic parkinsonism was established in two cases: one case of multiple system atrophy (in this patient loss of dopamine D2 receptors was found with [123I]iodobenzamide SPET performed 2 weeks after [123I]FP-CIT imaging) and one case of Parkinson's disease. Our data suggest that the positive predictive value of [123I]FP-CIT imaging is very high, and although the negative predictive value is lower, dopamine transporter imaging offers the prospect of a quick, objective method to confirm or exclude presynaptic parkinsonism in inconclusive cases.

Imaging of dopamine transporters with [123I]FP-CIT SPECT does not suggest a significant effect of age on the symptomatic threshold of disease in Parkinson's disease

Parkinson's disease (PD) is characterized neuropathologically by degeneration of the nigrostriatal dopaminergic pathway. With natural aging there is loss of dopaminergic cells in the substantia nigra and, consequently, loss of dopamine transporters in the striatum. It has been suggested that PD is caused by an accelerated rate of cell death. Conceptually, symptoms in idiopathic PD become apparent after a critical level of cell loss, the "symptom threshold." It has been suggested that this symptom threshold is independent of age. In this study, [123I]FP-CIT SPECT was used to assess the effect of aging on the density of striatal dopamine transporters in vivo in controls (n = 36) and early, drug-naive, patients with PD (n = 32). We found a significant age-associated decline of [123I]FP-CIT binding to striatal dopamine transporters in controls, but not in parkinsonian patients. This finding might give further support for the existence of an age-independent threshold in PD. In a subgroup of patients with hemi-PD, we found a significant loss of dopamine transporters bilaterally in the caudate nucleus and putamen. This loss was more pronounced in the putamen than in the caudate nucleus and the contralateral binding was significantly lower than the ipsilateral binding. By using age-corrected data, we estimated that in our particular patient group motor signs started when the loss of [123I]FP-CIT binding ratios in the putamen was 46-64%.

Loss of olfaction in de novo and treated Parkinson's disease: possible implications for early diagnosis

Olfactory dysfunction is a common finding in patients with Parkinson's disease (PD). As most studies reported on odor identification in more advanced and treated PD, we administered an odor detection, discrimination, and identification test to a heterogeneous, partly de novo, group of patients. Forty-one non-demented PD patients, 24 of whom had untreated early PD, and 18 healthy controls, were examined. Odor identification and discrimination data were corrected for odor detection scores. PD patients scored significantly lower on all olfactory tests. Interestingly, the subgroup of de novo patients with early PD also showed significant olfactory disturbances compared with healthy subjects. Within the PD group, using multiple regression analysis, we found a significant, negative correlation between odor discrimination measures and disease The present study is the first to describe decreased performance of PD patients on odor discrimination, in addition to the already well-established deficits in odor detection and identification. Furthermore, odor discrimination measures were related to disease severity, possibly indicating that at least some aspects of olfactory dysfunction in PD may be secondary to ongoing degenerative processes in PD. As significant olfactory impairments were found in early, de novo PD, olfactory tests may be useful in the early diagnosis of PD.

L-glutamate, L-arginine and L-citrulline levels in cerebrospinal fluid of Parkinson's disease, multiple system atrophy, and Alzheimer's disease patients

Alterations in neuronal nitric oxide (NO) production may play a role in the pathophysiology of Parkinson's disease (PD) Alzheimer's disease (AD), and multiple system atrophy (MSA). The biosynthesis of NO is dependent on the availability of L-arginine, the substrate for NO-synthase (NOS), and on L-glutamate, which stimulates NO synthesis via the NMDA receptor. In this process L-citrulline is formed. We measured the levels of these amino acids in cerebrospinal fluid (CSF) of 108 PD patients, 12 AD patients, 15 MSA patients and 21 healthy subjects. A slight but statistically significant elevation of CSF L-citrulline was found in MSA patients, while CSF L-glutamate was found to be significantly decreased in AD patients. We found no significant changes in L-arginine levels. Although the relation between the CSF levels of these amino acids and neuronal NO production is still unclear, our findings suggest that AD is associated with a decrease in NO synthesis.

Preclinical (premotor) Parkinson's disease

Parkinson's disease (PD) is an idiopathic disease caused by necrosis and apoptosis of dopaminergic cells in the brainstem, which are probably induced by oxidative stress. Current therapeutic strategies comprise symptomatic and restorative treatment. Neuroprotective treatment, however, is close to becoming reality. As neuroprotective therapy may be of particular benefit to the preclinical and/or very early PD patients, identifying patients in the early stages of the disease is a priority. Both [18F]dopa positron emission tomography (PET) and [123I]beta-CIT single photon emission computed tomography (SPECT) imaging may be useful tools in diagnosing early (preclinical) PD. As screening the whole population for preclinical PD is not realistic, one has to select subjects with a high risk for this disease. Olfactory disturbances, subtle neurocognitive dysfunction, visuomotor control abnormalities and, to a lesser degree, mood and personality disorders, have lately been suggested to precede or accompany early clinical motor hallmarks of PD. In an epidemiological study, 500 first-degree relatives of PD patients were assessed for these signs and symptoms, and [123I]beta-CIT SPECT was performed on patients in the top 10% and the bottom 10% with regard to sense of smell. In this report, the study design and initial data from this ongoing study will be presented.

Psychiatric complications in Parkinson's disease

Parkinson's disease (PD) is caused by an abnormal degeneration of the dopamine (DA) producing cells in the substantia nigra (SN) and ventral tegmentum area (VTA) in combination with a varying decay of the noradrenergic (locus coeruleus), cholinergic forebrain (nucleus basalis of Meynert) and serotoninergic (dorsal raphe nuclei) systems, leading to a multitude of motor and non-motor behavioral disturbances, known as parkinsonism. Normally, main dopamine depletion is restricted to the SN region with manifest (non)motor behavioral abnormalities caused by the inability to spontaneously switch between intern-cued cortical behavioral programmes. Clinical symptoms comprise motoric abnormalities, though subtle cognitive disturbances as well as psychological dysfunction with loss of mental flexibility and reactive depressive symptoms might be seen. These symptoms might be compensated in part by externally-cued behavior.

Normal cerebrospinal fluid glutathione concentrations in Parkinson's disease, Alzheimer's disease and multiple system atrophy

We measured total glutathione concentrations in the cerebrospinal fluid (CSF) of non-demented Parkinson's disease patients (PD; n=71), demented PD patients (PDD; n=13), multiple system atrophy patients (MSA; n=10), Alzheimer's disease patients (AD; n=17) and age-matched controls (n=21). No statistically significant differences in the mean total CSF glutathione concentrations were found between groups and dopaminomimetic treatment was not found to have any effect on total CSF glutathione levels. Our main conclusion is that total glutathione is not useful as a CSF marker for assumed oxidative stress in patients with PD, MSA or AD.

Leads for the development of neuroprotective treatment in Parkinson's disease and brain imaging methods for estimating treatment efficacy

Patients suffering from Parkinson's disease display severe and progressive deficits in motor behavior, predominantly as a consequence of the degeneration of dopaminergic neurons, located in the mesencephalon and projecting to striatal regions. The cause of Parkinson's disease is still an enigma. Consequently, the pharmacotherapy of Parkinson's disease consists of symptomatic treatment, with in particular L-dihydroxyphenylalanine (L-DOPA) and/or dopamine receptor agonists. These induce a dramatic initial improvement. However, serious problems gradually develop during long-term treatment. Therefore, a more rational, c.q. causal treatment is needed which requires the introduction of compounds ameliorating the disease process itself. The development of such compounds necessitates (1) more information on the etiopathogenesis, i.e., the cascade of events that ultimately leads to degeneration of the dopaminergic neurons, and (2) brain imaging methods, to estimate the extent of the degeneration of the dopaminergic neurons in the living patient. This is not only important for the early diagnosis, but will also allow to monitor the effectiveness of alleged neuroprotective compounds on a longitudinal base. In this paper, etiopathogenic mechanisms are highlighted along the line of the oxidative stress hypothesis and within this framework, attention is mainly focused on the putative role of glutathione, dopamine auto-oxidation and phase II biotransformation enzymes. Especially, drugs able to increase the activity of phase II biotransformation enzymes seem to elicit a broad-spectrum (neuro)protective response and look very promising leads for the development of neuroprotective treatment strategies in Parkinson's disease. New developments in brain imaging methods (single photon emission computed tomography (SPECT) and positron emission tomography (PET)) to visualize the integrity of the striatal dopaminergic neurons in humans are highlighted as well. Especially, the introduction of radioligands that bind selectively to the dopamine transporter seems to be a significant step forward for the early diagnosis of Parkinson's disease. Performing these brain imaging studies with fixed time intervals does not only create the possibility to follow the degeneration rate of the dopaminergic neurons in Parkinson's disease but also provides the opportunity to estimate therapeutic effects of putative neuroprotective agents in the individual patient.

Dopaminomimetic psychosis in Parkinson's disease patients: diagnosis and treatment

Dopaminomimetic agents, which were rationally designed to reverse dopamine deficits in the substantia nigra and ventral tegmental area of the parkinsonian midbrain, effectively attenuate deficits in motor and non-motor behavior thought to be elicited by dopamine deficiencies in the striatal and frontal limbic regions, respectively. On the other hand, dopaminomimetic medications may also induce perturbations in postsynaptic peptides, causing dopaminergic hypersensitivity. Drug-induced chronic dopaminomimetic psychosis afflicts about one-fifth of PD patients on dopaminergic regimens. Although the long-held mechanism for psychosis in PD is excessive stimulation of mesocorticolimbic dopamine receptors, interactions between dopamine and serotonin, as well as participation of serotonin-modulated GABAergic neurons may also contribute to the pathophysiology. Reduction or withdrawal of anticholinergic agents, amantadine, and dopamine precursors or agonists constitutes a first approach to the problem but is often insufficient. Unfortunately, typical antipsychotic agents such as haloperidol, which selectively antagonizes dopamine D-2 receptors, can induce extrapyramidal syndromes such as tardive parkinsonism. On the other hand, emerging atypical neuroleptics such as clozapine, quetiapine, and olanzapine, which antagonize 5HT-2A receptors (among others), inhibit D-2 receptors to a lesser degree and exhibit selective binding to mesolimbic (vs. striatal) dopamine receptors. The limbic selectivity of these agents appears to be of greater magnitude than that typical of risperidone. In addition, the selective antiserotonergic agent ondansetron is a prospective therapeutic option. The pharmacologic properties of these agents are explored.

Identification of axial rigidity during locomotion in Parkinson disease

OBJECTIVES

To identify coordination changes and stability in the movements of the trunk during locomotion in Parkinson disease (PD) as a function of walking velocity.

STUDY DESIGN

Comparison of treadmill locomotion with an opto-electronic tracking device.

PATIENTS

Newly diagnosed patients with PD (n = 27) and a group of healthy control subjects (n = 11).

RESULTS

Coordination between transversal pelvic and thoracic rotations showed significantly smaller changes in mean relative phase (p < .0001) and lower variability in relative phase (p < .0001) in the PD group. No significant differences were found in stride duration and variability in stride duration.

CONCLUSIONS

The relative phase data contradict traditional notions of increased variability in motor control in PD and pinpoint the importance of the trunk in identifying axial rigidity. This discrepancy may be due to lack of control for walking velocity in earlier studies. It is concluded that systematic manipulation of walking velocity can identify coordination deficits and rigidity in trunk movement. This coordination of trunk movement can also be a sensitive measure for (early) diagnosis and the assessment of movement and pharmacological therapy in PD.

Imaging of dopamine transporters with iodine-123-FP-CIT SPECT in healthy controls and patients with Parkinson's disease

Several SPECT studies reported decreased striatal 123I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodoph enyl)nortropane ([123I]FP-CIT) binding in patients with Parkinson's disease. For application in routine clinical studies, information on the reliability and reproducibility of the [123I]FP-CIT SPECT technique is critical. This study reports on the reliability and reproducibility of [I23I]FP-CIT SPECT in healthy control subjects and patients with Parkinson's disease using two different analysis protocols: the conventional region of interest (ROI) protocol and a newly developed, fully automatic, operator-independent volume of interest (VOI) protocol.

METHODS

We performed repeated [123I]FP-CIT SPECT scans in 6 healthy control subjects and 10 patients with Parkinson's disease to measure scan-to-scan variations. Scintigraphic data were analyzed 3 hr after injection of the radiotracer.

RESULTS

In controls, the mean test/retest for the ratio of the striatal-to-nonspecific [123I]FP-CIT uptake were (3.79 +/- 0.67/3.82 +/- 0.74) and (4.16 +/- 0.70/4.08 +/- 0.97) for the ROI and VOI technique, respectively. No significant differences were measured between test/retest studies. The mean test/retest variability for the ROI technique was low (7.25%) with excellent reliability (rho = 0.99). In addition, the mean test/retest variability for the VOI technique was also low (7.47%) with very high reliability (rho = 0.95). In Parkinson's disease patients, we found mean test/retest for the striatal-to-nonspecific [123I]FP-CIT ratio of (1.78 +/- 0.23/1.79 +/- 0.25) and (1.83 +/- 0.31/1.85 +/- 0.35) using the ROI and VOI technique, respectively. Also in patients, these results did not differ significantly between test/retest studies. The mean test/retest variability for the ROI technique was low (7.90%) with excellent reliability (rho = 1.00). In addition, the mean test/retest variability for the VOI technique was also low (7.36%) with high reliability (rho = 0.96).

CONCLUSION

Reliable and reproducible results were obtained with the ROI, as well as the VOI technique, for the analysis of striatal dopamine transporters with [123I]FP-CIT SPECT in healthy controls and Parkinson's disease patients. The use of an operator-independent method will be a great advantage in routine clinical studies.

Depression in Parkinson's disease. The impact of symptom overlap on prevalence

The reported prevalence of depression concomitant with Parkinson's disease varies greatly in the literature, which may partly be explained by symptom overlap. To determine the impact of symptom overlap on the prevalence, the authors tested 100 Parkinson's disease patients for major depression (DSM-III-R) with both a standard, inclusive method and a diagnostic-etiologic, exclusive method. The authors found that the prevalence detected with the inclusive method (23%) decreased when the exclusive method was used (13%), which was mainly caused by lower scores on the item "loss of interest." The study's findings give empirical support for the relevance of the new category in DSM-IV "mood disorder due to a general medical condition."

Iodine-123-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iod ophenyl)tropane SPECT in healthy controls and early-stage, drug-naive Parkinson's disease

The aims of this study were to investigate whether the loss of striatal dopamine transporters in early and drug-naive patients with Parkinson's disease could be demonstrated by means of 123I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodoph enyl)tropane (123I-FP-CIT) SPECT in a 1-day protocol and whether the SPECT measures were correlated with disease severity.

METHODS

Twenty-one early-stage and drug-naive Parkinson's disease patients (age range 42-73 yr; mean age 55.5 yr) and 14 healthy controls (age range 28-83 yr; mean age 53.6 yr) were examined. SPECT image acquisition was always performed at 3 hr postinjection. The ratio of specific to nonspecific striatal 123I-FP-CIT binding was used as the outcome measure.

RESULTS

All striatal 123I-FP-CIT ratios were significantly lower in the Parkinson's disease group compared to those in the control group. The mean reduction in the putamen was 57% of the control mean, and that in the caudate nucleus was 29% of the control mean. Patients with unilateral Parkinson's disease showed a bilateral loss of striatal 123I-FP-CIT binding. Discriminant function analysis, using the 123I-FP-CIT SPECT data of the ipsilateral and contralateral putamen, predicted group membership in all cases; the contralateral putamen accounted for the greatest difference between the Parkinson's disease patients and the controls. In the control group, a clear decline in 123I-FP-CIT binding was found with aging, amounting to 9.6%/decade. Unexpectedly, in the Parkinson's disease group, regression analysis revealed that neither severity of disease nor age accounted for a significant part of the variance in striatal SPECT measures.

CONCLUSION

Our findings indicate that 123I-FP-CIT SPECT is a reliable method to discriminate between early, drug-naive Parkinson's disease patients and healthy controls and to identify patients in the preclinical phase of Parkinson's disease. Possibly due to the relatively homogeneous group of Parkinson's disease patients and the use of a suboptimal outcome measure, no significant correlations were found between striatal 123I-FP-CIT binding ratios and disease severity, such as were established earlier with 123I-beta-CIT. Further research is necessary to interpret these findings.

Drug-naive patients with Parkinson's disease in Hoehn and Yahr stages I and II show a bilateral decrease in striatal dopamine transporters as revealed by [123I]beta-CIT SPECT

Ten healthy subjects and 16 patients with early Parkinson's disease (PD) were examined with single photon emission computed tomography (SPECT) and [123I]beta-CIT, a ligand for the dopamine (DA) transporter. Only drug-naive patients were examined since the expression of and binding to DA transporters may be influenced by dopaminergic medication. The main finding was a significant reduction in [123I]beta-CIT binding in the ipsi- and contralateral striatal regions, especially in the putamen, which showed a mean reduction of 65% of the control mean. Discriminant function analysis of the putaminal [123I]beta-CIT binding measures classified 100% of the cases in the correct group. Disease severity correlated negatively and highly significantly with the binding measures. Tremor ratings did not correlate with the SPECT measures, whereas rigidity, and to a lesser extent bradykinesia, did. Patients with unilateral PD showed a bilateral loss of striatal DA transporters. Our findings indicate that with [123I]beta-CIT SPECT it is possible to diagnose PD in subjects with very mild symptoms and signs. Moreover, finding a bilateral loss of striatal DA transporters in patients with unilateral PD also suggests that it may be possible to identify subjects in the preclinical phase of the disease.

[123I]beta-CIT single-photon emission tomography in Parkinson's disease reveals a smaller decline in dopamine transporters with age than in controls

In vivo studies using single-photon emission tomography (SPET) and positron emission tomography have shown an age-related decline in the number of striatal dopamine transporters in healthy subjects. We examined ten healthy subjects and 33 de novo patients with Parkinson's disease (PD) using [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I]beta-CIT) SPET. A clear age-related loss of dopamine transporters was found in the healthy subjects. In the PD group, controlling for the contribution of disease severity, we found a small (compared with controls) but significant decrease with aging, though only in the ipsilateral regions. This aging effect was especially pronounced in younger patients. We conclude that the use of age-correct SPET data in PD, based on studies with healthy subjects, may lead to an under- or an overestimation of the striatal binding measures.

[123I]FP-CIT SPECT shows a pronounced decline of striatal dopamine transporter labelling in early and advanced Parkinson's disease

OBJECTIVES

The main neuropathological feature in Parkinson's disease is a severe degeneration of the dopaminergic neurons in the substantia nigra resulting in a loss of dopamine (DA) transporters in the striatum. [123I]beta-CIT single photon emission computed tomography (SPECT) studies have demonstrated this loss of striatal DA transporter content in Parkinson's disease in vivo. However, studies with this radioligand also showed that an adequate imaging of the striatal DA transporter content could only be performed on the day after the injection of radioligand, which is not convenient for outpatient evaluations. Recently, a new radioligand [123I]FP-CIT, with faster kinetics than beta-CIT, became available for imaging of the DA transporter with SPECT, and the applicability of this ligand was tested in patients with early and advanced Parkinson's disease, using a one day protocol.

METHODS

[123I]FP-CIT SPECT was performed in six patients with early and 12 patients with advanced Parkinson's disease, and in six age matched healthy volunteers.

RESULTS

Compared with an age matched control group striatal [123I]FP-CIT uptake in patients with Parkinson's disease was decreased, and this result was measurable three hours after injection of the radioligand. In the Parkinson's disease group the uptake in the putamen was reduced more than in the caudate nucleus. The contralateral striatal uptake of [123I]FP-CIT was significantly lower than the ipsilateral striatal uptake in the Parkinson's disease group. Specific to non-specific striatal uptake ratios correlated with the Hoehn and Yahr stage. A subgroup of patients with early Parkinson's disease also showed significantly lower uptake in the putamen and lower putamen:caudate ratios than controls.

CONCLUSION

[123I]FP-CIT SPECT allows a significant discrimination between patients with Parkinson's disease and age matched controls with a one day protocol, which will be to great advantage in outpatient evaluations.

rCBF SPECT in Parkinson's disease patients with mental dysfunction

Functional imaging of the brain using SPECT provides information correlative to the alterations of regional blood flow. In this paper we review the literature pertaining to SPECT in Parkinson's disease with and without dementia and depression. Parkinson's disease itself is not associated with a consistent pattern of cerebral blood flow alterations in the basal ganglia, but reduced parietal blood flow is more often reported. The heterogeneity of blood flow changes possibly reflects the multifactorial pathophysiology of the disease. In demented Parkinson's disease patients frontal hypoperfusion is often found or bilateral temporoparietal deficits, probably indicative of concomitant Alzheimer's disease. The SPECT studies undertaken in depressed patients with and without Parkinson's disease show highly conflicting and inconsistent results, probably due to methodological and diagnostic flaws (especially the inclusion of demented Parkinson patients). Several lines of reasoning point to a prefrontal dysfunction and future SPECT studies are planned to study this region in non-demented Parkinson's disease patients with and without major depression.

IBZM- and CIT-SPECT of the dopaminergic system in parkinsonism

Parkinsonism is most of the time caused by idiopathic Parkinson's disease (IPD). Considering the differences in therapeutic response and prognosis, in vivo discrimination between IPD and "parkinsonism-plus" syndromes is important. Recently, ligands have become available for imaging the pre- and postsynaptic dopaminergic system by Single Photon Emission Computed Tomography (SPECT). Visualization of postsynaptic D2 dopamine receptors using 123I-iodobenzamide (123I-IBZM) may contribute to the differential diagnosis between IPD and "parkinsonism-plus" syndromes as IPD is a pure presynaptic disease. Imaging of the presynaptic dopamine transporters using [123I] beta-CIT (2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane) may be used as a diagnostic technique. Early disease detection in subjects suspected to be at risk for developing IPD has become possible using [123I] beta-CIT or other ligands for the dopamine transporter. Furthermore, with SPECT one is probably able to monitor in an objective way the efficacy of new pharmacological therapies.

Practical benefit of [123I]FP-CIT SPET in the demonstration of the dopaminergic deficit in Parkinson's disease

Loss of striatal dopamine (DA) transporters in Parkinson's disease (PD) has been accurately assessed in vivo by single-photon emission tomography (SPET) studies using [123I]beta-CIT. However, these studies have also shown that adequate imaging of the striatal DA transporter content can be performed only 20-30 h following the injection of [123I]beta-CIT, which is not convenient for routine out-patient evaluations. Recently, a new ligand, N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl) tropane (FP-CIT), became available for in vivo imaging of the DA transporter. The faster kinetics of [123I]FP-CIT have been shown to allow adequate acquisition as early as 3 h following injection. In the present study, loss of striatal DA transporters in five non-medicated PD patients was assessed on two consecutive SPET scans, one with [123I]beta-CIT (24 h following injection) and one with [123I]FP-CIT (3 h following injection). The ratios of specific to non-specific [123I]FP-CIT uptake in the caudate nucleus and putamen were consistently 2.5-fold lower than those of [123I]beta-CIT. However, when the uptake ratio of both ligands in these brain regions of patients was expressed as a percentage of the uptake ratio found in healthy controls, both the decrease and the variation of the data were similar. It is concluded on the basis of these findings that [123I]FP-CIT seems as good as [123I]beta-CIT for the assessment of the dopaminergic deficit in PD. The faster kinetics of [123I]FP-CIT are a clear advantage.

Olanzapine in the treatment of dopaminomimetic psychosis in patients with Parkinson's disease

We studied the effect of olanzapine (1 to 15 mg/d) in 15 nondemented parkinsonian patients with drug-induced psychosis. Psychotic symptoms decreased significantly during treatment, and there was no worsening of extrapyramidal symptoms. These results suggest that olanzapine is a well-tolerated and effective treatment for drug-induced psychosis in nondemented patients with Parkinson's disease.

International (NL-UK) double-blind study of Sinemet CR and standard Sinemet (25/100) in 170 patients with fluctuating Parkinson's disease

One hundred and seventy patients with fluctuating Parkinson's disease participated in an international clinical trial to compare the effects of controlled-released Sinemet 50/200 (mg carbidopa/mg levodopa; Sinemet CR) with standard Sinemet 25/100 (Sinemet STD). The study design involved an 8-week open-label titration (dose-finding) phase (STD and CR preparations given individually during weeks 1-4 and 5-8 respectively) followed by a 24-week double-blind, double-dummy (placebo) treatment period. Drug efficacy was assessed using: (a) data from patients' diaries (i.e. "on-off" periods) (b) the functional disability profile (Northwestern University Disability Scale), (c) the neurological signs and symptoms (New York University Parkinson's Disease Scale, NYUPDS), (d) global evaluations made by the patient and treating physician and (e) the patient's evaluation of sleep. The results indicate that the number of "off" periods and the total NYUPDS score decreased significantly in the patients treated with Sinemet CR compared with those treated with Sinemet STD. Furthermore, the patient's global evaluation was significantly better in the Sinemet CR group. The number of drug-related adverse experiences was similar in the two groups, and only one serious event of this nature was reported.

Localization of the gene for rapidly progressive autosomal dominant parkinsonism and dementia with pallido-ponto-nigral degeneration to chromosome 17q21

Rapidly progressive autosomal dominant parkinsonism and dementia with pallido-ponto-nigral degeneration (PPND) is a neurodegenerative disorder which begins later in life (> 30 years of age) and is characterized by rapidly progressive parkinsonism, dystonia, dementia, perservative vocalizations and pyramidal tract dysfunction. The disease is observed in a large American family that includes almost 300 members in nine generations with 34 affected individuals. In this kindred evidence for linkage to chromosome 17q21 was obtained with a maximum lod score of 9.08 for the D17S958 locus. Multilocus analysis positions the disease gene in an approximately 10 cM region between D17S250 and D17S943. Notably, the disease locus for a clinically distinct familial neurodegenerative disease named 'disinhibition-dementia-parkinsonism-amyotrophy complex' (DDPAC) was recently mapped to the same region of chromosome 17, suggesting that PPND and DDPAC may possibly originate from mutations in the same gene.

Evaluation of [123I] beta-CIT binding with SPECT in controls, early and late Parkinson's disease

The main neuropathological feature in Parkinson's disease (PD) is a severe degeneration of the dopaminergic neurons in the substantia nigra resulting in a loss of dopamine in the striatum. Recently, a new radioligand (beta-CIT) for single photon emission computed tomography (SPECT) became available for in vivo imaging of the dopamine transporter on nerve endings of dopaminergic neurons in the striatum. The present results demonstrate that [123I]-beta-CIT SPECT allows a discrimination between early and late PD patients. In our opinion, these preliminary data suggest that [123I]-beta-CIT SPECT should be used from now on in longitudinal studies (such as the DATATOP study) in which the effects of (putative) neuroprotective interventions in PD are monitored.

Effects of unilateral 6-hydroxydopamine lesions on neuropeptide immunoreactivity in the basal ganglia of the common marmoset, Callithrix jacchus, a quantitative immunohistochemical analysis

Previous immunocytochemical studies in rats have indicated that striatal dopamine depletion leads to an increase in enkephalin-immunoreactivity and a decrease in substance P-immunoreactivity in the striatum. Similar studies in primates have lead to contradictory results. In the present study changes in tyrosine hydroxylase-, met-enkephalin- and substance P-immunoreactivity were determined in the basal ganglia of 6 common marmosets Callithrix jacchus following dopamine depletion by unilateral intracerebral 6-hydroxydopamine (6-OHDA) injections using three different survival times. The non-lesioned side served as an intra-individual control. Tyrosine hydroxylase immunoreactivity was strongly reduced in the entire ipsilateral striatum. Enkephalin-immunoreactivity was increased throughout the striatum. Substance P-immunoreactivity was significantly increased in only one case in the caudate nucleus and in two cases in the putamen, while in other cases either a non-significant increase or decrease was found. Therefore, the results of the present study indicate that in marmosets dopamine has a inhibiting effect on the levels of striatal enkephalin, while its effect on substance P (SP) appears to be absent.

Histopathologic correlates of white matter changes on MRI in Alzheimer's disease and normal aging

We investigated the histopathologic correlates of white matter changes in Alzheimer's disease (AD) patients (n = 6) and controls (n = 9) using postmortem MRI. White matter changes were rated on a 0 to 3 scale in 51 regions. Histopathologically, we subjectively rated the loss of myelinated axons in the deep and periventricular white matter, denudation of the ventricular ependyma, gliosis, width of the perivascular spaces, and leptomeningeal congophilic angiopathy; we measured structural changes in the walls of the blood vessels in the white matter in micrometers. The AD brains displayed significantly more white matter hyperintensities on MRI than controls. Histopathologically, the denudation of the ventricular ependyma and the gliosis were significantly more severe in AD than in controls, and there was a trend toward more loss of myelinated axons in the deep white matter in the AD brains (p = 0.07). The MRI abnormalities correlated with the loss of myelinated axons in the deep white matter (r' = 0.37; p < 0.01) and with the denudation of the ventricular lining (r' = 0.54; p < 0.01). We could not find any evidence for arteriolosclerosis, but the mean thickness of the adventitia of the arteries of the deep white matter in AD almost doubled the value in control brains (p = 0.0009). We conclude that white matter abnormalities in AD patients and controls consist of loss of myelinated axons, probably caused by arterial changes and breakdown of the ventricular lining. Since imaging/histopathologic correlation was similar in AD patients and controls, these changes probably represent some form of accelerated aging.