Brain alpha-synuclein accumulation in multiple system atrophy, Parkinson's disease and progressive supranuclear palsy: a comparative investigation

Alpha-synuclein is a major component of Lewy bodies and glial cytoplasmic inclusions, pathological hallmarks of idiopathic Parkinson's disease and multiple system atrophy, and it is assumed to be aetiologically involved in these conditions. However, the quantitative status of brain alpha-synuclein in different Parkinsonian disorders is still unresolved and it is uncertain whether alpha-synuclein accumulation is restricted to regions of pathology. We compared membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein, both the full-length 17 kDa and high molecular weight species, by western blotting in autopsied brain of patients with Parkinson's disease (brainstem-predominant Lewy body disease: n = 9), multiple system atrophy (n = 11), progressive supranuclear palsy (n = 16), and of normal controls (n = 13). Brain of a patient with familial Parkinsonism-dementia due to alpha-synuclein locus triplication (as positive control) showed increased membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein levels with abundant high molecular weight immunoreactivity. In multiple system atrophy, a massive increase in 17 kDa membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein was observed in highly pathologically affected regions, including putamen (+1760%, range +625-2900%), substantia nigra [+1000% (+356-1850%)], and white matter of internal capsule [+2210% (+430-6830%)] together with numerous high molecular weight species. Levels of 17 kDa membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein were only modestly increased in less affected areas (cerebellar cortex, +95%; caudate, +30%; with both also showing numerous high molecular weight species) and were generally normal in cerebral cortices. In both Parkinson's disease and progressive supranuclear palsy, membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein levels were normal in putamen and frontal cortex whereas a trend was observed for variably increased 17 kDa membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein concentrations [+184% (-60% to +618%)] with additional high molecular weight species in Parkinson's disease substantia nigra. No obvious correlation was observed between nigral membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein accumulation and Lewy body density in Parkinson's disease. Two progressive supranuclear palsy cases had membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein accumulation in substantia nigra similar to multiple system atrophy. Several Parkinson's disease patients had very modest high molecular weight membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein accumulation in putamen. Levels of 17-kDa membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein were generally positively correlated with those of high molecular weight membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein and there was a trend for a positive correlation between striatal dopamine loss and 17-kDa membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein concentrations in multiple system atrophy. Brain membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein accumulations in Parkinson's disease and multiple system atrophy are regionally specific, suggesting that these sporadic alpha-synucleinopathies, unlike familial Parkinsonism-dementia, are not associated with a simple global over-expression of the protein. Despite a similar extent of dopamine depletion, the magnitude of brain membrane-associated, sodium dodecyl sulfate-soluble alpha-synuclein changes is disease specific, with multiple system atrophy clearly having the most severe accumulation. Literature discrepancies on alpha-synuclein status in 'Parkinson's disease' might be explained by inclusion of cases not having classic brainstem-predominant Lewy body disease and by variable alpha-synuclein accumulation within this diagnostic classification.

Course in Parkinson disease subtypes: A 39-year clinicopathologic study

BACKGROUND

Individual variations in the course of Lewy body Parkinson disease (PD) are well known. Patients have been classified into different clinical subtypes to identify differences in the course among the subgroups. Several studies indicate that the outcome is more favorable in tremor dominant (TD) cases but others report no difference. A majority of progression studies are based on cross-sectional single point data or short-term clinical observations. The lack of longitudinally followed autopsy-confirmed PD cohort remains a major weakness in the literature. Biochemical studies of brain indicate most pronounced abnormalities in akinetic/rigid (AR) and the least in TD cases. We postulate that PD course in these subtypes is concordant with the biochemical findings.

OBJECTIVE

To compare the course in TD, mixed (MX), and AR subtypes of PD.

METHODS

Longitudinal clinical follow-up and autopsy studies were performed on 166 patients with PD over 39 years (1968-2006). Patients were classified into TD, AR, and MX based on the entire clinical course. Only the pathologically confirmed PD cases were included.

RESULTS

Sixty-six percent of cases had MX, 26% AR, and 8% TD profile. The age at onset was younger (p < 0.001) and progression to Hoehn & Yahr stage 4 was slower (p = 0.016) in the TD cases. Dementia was most common in AR (p = 0.039) and the least common in TD. In general, the course was most favorable in TD, followed by MX and AR subgroups.

CONCLUSION

The three subtypes of Parkinson disease have different courses which are concordant with the differences in brain biochemical abnormalities.

FGF20 and Parkinson's disease: no evidence of association or pathogenicity via alpha-synuclein expression

Genetic variation in fibroblast growth factor 20 (FGF20) has been associated with risk of Parkinson's disease (PD). Functional evidence suggested the T allele of one SNP, rs12720208 C/T, altered PD risk by increasing FGF20 and alpha-synuclein protein levels. Herein we report our association study of FGF20 and PD risk in four patient-control series (total: 1,262 patients and 1,881 controls), and measurements of FGF20 and alpha-synuclein protein levels in brain samples (nine patients). We found no evidence of association between FGF20 variability and PD risk, and no relationship between the rs12720208 genotype, FGF20 and alpha-synuclein protein levels.

GCH1 expression in human cerebellum from healthy individuals is not gender dependent

Dopa-responsive dystonia (DRD) is a familial childhood-onset disease characterized by fluctuating dystonia, associated with tremor and parkinsonism in some patients. In most families the disease displays autosomal dominant inheritance due to mutations in the GTP cyclohydrolase 1 gene (GCH1). Penetrance and symptom severity display strong female predominance for which gender-specific GCH1 expression has been hypothesized. In this study, GCH1 mRNA expression was measured in cerebellar tissue from 66 healthy human subjects (30 women), and in cerebellar and nigral tissue from eight individuals. No significant difference was found between men and women with small effect sizes observed. Although the correlation between cerebellar and nigral GCH1 expression remains to be further examined, this exploratory study does not support gender-specific GCH1 expression being the basis for the skewed gender distribution observed in DRD patients.

Alpha-synuclein and tyrosine hydroxylase expression in acute rotenone toxicity

Chronic low-dose (2-3 mg/kg/day) rotenone infusion produces clinical features and biological markers of Parkinson's disease (PD) in some rats. A significant proportion of rats, however, die of acute rotenone toxicity. Most studies have focused on chronic rotenone-infused rats. It has not been established if the animals that die of acute low-dose rotenone toxicity manifest clinical or pathological evidence of PD. In the present study, six rats that received continuous 3 mg/kg/day subcutaneous rotenone infusion, became moribund and were euthanized after five days were compared with ten vehicle infused animals sacrificed 14, 28 or 56 days after placebo infusion. All rotenone-infused rats had significant motor function decline beginning one day after the infusion and progressive worsening in the physical condition until they became severely akinetic, at which point they were euthanized. In the substantia nigra of rotenone-treated rats, four of six had reduced numbers of tyrosine hydroxylase-positive neurons and all six had increased nigral alpha-synuclein expression. Our observations show that even a short duration of low-dose subcutaneous rotenone infusion can induce clinical and pathological markers of PD in some rats. The pathophysiology of the enhanced susceptibility to PD in some animals remains to be established.

Postmortem brain fatty acid profile of levodopa-treated Parkinson disease patients and parkinsonian monkeys

Fatty acids play a critical role in brain function but their specific role in the pathophysiology of Parkinson disease (PD) and levodopa-induced motor complications is still unknown. From a therapeutic standpoint, it is important to determine the relation between brain fatty acids and PD because the brain fatty acid content depends on nutritional intake, a readily manipulable environmental factor. Here, we report a postmortem analysis of fatty acid profile by gas chromatography in the brain cortex of human patients (12 PD patients and nine Controls) as well as in the brain cortex of monkeys (four controls, five drug-naive MPTP monkeys and seven levodopa-treated MPTP monkeys). Brain fatty acid profile of cerebral cortex tissue was similar between PD patients and Controls and was not correlated with age of death, delay to autopsy or brain pH. Levodopa administration in MPTP monkeys increased arachidonic acid content (+7%; P < 0 .05) but decreased docosahexaenoic acid concentration (-15%; P < 0.05) and total n-3:n-6 polyunsaturated fatty acids ratio (-27%; P < 0.01) compared to drug-naive MPTP animals. Interestingly, PD patients who experienced motor complications to levodopa had higher arachidonic acid concentrations in the cortex compared to Controls (+13.6%; P < 0.05) and to levodopa-treated PD patients devoid of motor complications (+14.4%; P < 0.05). Furthermore, PD patients who took an above-median cumulative dose of levodopa had a higher relative amount of saturated fatty acids but lower monounsaturated fatty acids in their brain cortex (P < 0.01). These results suggest that changes in brain fatty acid relative concentrations are associated with levodopa treatment in PD patients and in a non-human primate model of parkinsonism.

Parkinson's disease, stroke, and related epidemiology

We investigated the prevalence of cerebrovascular disease and other comorbidities in Parkinson's disease (PD) patients compared to the general population. Five hundred PD patients were chosen randomly from one author's (A.H.R.) database. Age- and sex-matched controls were derived from 270 patients with essential tremor from the same database and from 490 patients in a general practitioner's database. Age, hypertensive status, smoking status, coronary artery disease, orthostatic hypotension, diabetes mellitus, and symptomatic cerebrovascular disease (stroke or transient ischemic attack) were assessed. Statistical analysis was performed using Pearson chi(2) testing and binary logistic regression analysis. The prevalence of coronary artery disease, hypertension, diabetes mellitus, and orthostatic hypotension was similar among groups. The PD group had more patients who never smoked and less current smokers than the other groups. While there were similar frequencies of symptomatic cerebrovascular disease among groups, the prevalence of stroke was lower in PD patients. This difference disappeared upon stratification into groups based on smoking status and in the addition of smoking as a covariate in the multivariate analysis. Diminished smoking in PD patients likely plays a role in our finding of decreased stroke in patients with PD. Increased access to appropriate neurological care and subsequent prevention of stroke after a warning transient ischemic attack may also play a role, as may diminished levels of excitotoxic neurotransmitters in PD patients.

Levodopa in the treatment of Parkinson's disease: Current controversies

Levodopa is the most effective symptomatic agent in the treatment of Parkinson's disease (PD) and the "gold standard" against which new agents must be compared. However, there remain two areas of controversy: (1) whether levodopa is toxic, and (2) whether levodopa directly causes motor complications. Levodopa is toxic to cultured dopamine neurons, and this may be a problem in PD where there is evidence of oxidative stress in the nigra. However, there is little firm evidence to suggest that levodopa is toxic in vivo or in PD. Clinical trials have not clarified this situation. Levodopa is also associated with motor complications. Increasing evidence suggests that they are related, at least in part, to the short half-life of the drug (and its potential to induce pulsatile stimulation of dopamine receptors) rather than to specific properties of the molecule. Treatment strategies that provide more continuous stimulation of dopamine receptors provide reduced motor complications in MPTP monkeys and PD patients. These studies raise the possibility that more continuous and physiological delivery of levodopa might reduce the risk of motor complications. Clinical trials to test this hypothesis are underway. We review current evidence relating to these areas of controversy.

Anomalies of asymmetry of clinical signs in parkinsonism

Parkinson's disease (PD) is characterized by a minimum of two of three features: tremor, rigidity, and bradykinesia. Asymmetry of these features is often considered to support a diagnosis of PD in contrast to other parkinsonian syndromes. All major manifestations of PD are often more pronounced on the side first manifesting features of PD. Significant dissociation of features on the contralateral side, along with other variants of presentation involving the contralateral side, are rarely observed. To determine the frequency and significance of unusual asymmetry in parkinsonism, we retrospectively examined 613 patients clinically diagnosed as idiopathic PD for presence of unusual asymmetries of clinical features. Three groups of patients with unusual asymmetrical clinical findings were identified. Group 1 comprised 10 patients followed for an average of 6 years presenting with rest tremor most prominent in one lower limb and contralateral upper limb. Group 2 comprised 24 patients followed for an average of 5.5 years with action tremor most prominent on the side contralateral to the side of most prominent rest tremor. Group 3 comprised 33 patients followed for an average of 10 years who had parkinsonian signs of greatest severity on one side but subsequently, over an average of 5.4 years, became gradually more prominent on the opposite side. In Group 3, 15 of 33 patients (45%) demonstrated evolution to a rigid form of parkinsonism with disappearance of rest tremor over an average of 7.1 years after presentation. A small percentage (11%) of Parkinson's patients in our clinic demonstrated anomalous asymmetrical clinical findings, which indicates that (1) the disease process may begin in different topographic sites on each side; (2) rest tremor and action tremor may have different anatomical bases; (3) the disease process may progress at different rates on different sides; and (4) tremor becomes less pronounced with progression of disease in some patients with Parkinsonism.

Essential tremor course and disability: A clinicopathologic study of 20 cases

OBJECTIVE

To correlate autopsy findings with the clinical course and disability profile in clinically diagnosed longitudinally followed autopsied essential tremor (ET) patients.

METHODS

All ET patients followed by one neurologist between 1970 and 2001 who came to autopsy were included. Clinical features and disability were recorded prospectively. Autopsy studies were performed by a qualified neuropathologist.

RESULTS

Twenty cases (10 men and 10 women) had ET onset between childhood and age 68 (median 46.5 years). Six cases had additional features of Parkinson syndrome (PS), with presence of bradykinesia, rigidity, and rest tremor (RT). These included progressive supranuclear palsy (PSP; n = 2), drug-induced parkinsonism (n = 2), idiopathic Parkinson disease (PD; n = 1), and basal ganglia status cribrosus (n = 1). Of the remaining 14 ET cases, 6 had additional RT but no bradykinesia or rigidity. Ten of these 14 (71%) reported physical disability. Eleven of the 14 (79%) had only upper limb (UL) tremor at onset, and 8 of these 11 (73%) had subsequent cranial extension of tremor. Two patients clinically had mild cerebellar ataxia but no cerebellar histologic abnormality. There was no consistent brain pathology in the ET or ET + RT cases.

CONCLUSIONS

UL tremor was the most common onset, which often progressed to the cranial musculature. Functional disability and psychological distress were common in these patients. Functional disability was related to the UL tremor. Six of 20 (30%) had additional features of PS. Six of the remaining 14 (43%) had ET and RT; there was no identifiable pathology in these cases. The risk of PD in ET cases was comparable with that in the general population. PSP in two cases was incidental comorbidity.

Human brain dopamine metabolism in levodopa-induced dyskinesia and wearing-off

The objective of this study was to identify dopamine (DA) metabolism pattern in Lewy body Parkinson's disease (PD) patients with dyskinesia (Dysk) only, with wearing-off (WO) only, or no motor complications (NMC) induced by levodopa (LD). DA, homovanillic acid (HVA), 3,4-dihydroxyphenylacetic acid (DOPAC), and 3-methoxytyramine (3-MT) were measured individual basal ganglia nuclei of nine PD patients who received LD for 6-18 years. Three patients had only Dysk, three only WO, and three had neither Dysk nor WO. Biochemical measurements in PD brains were compared with four non-neurological control brains from individuals matched for age and post-mortem retrieval time. DA levels in the PD were reduced in the caudate by 87% and putamen by 99%. In the caudates, the HVA/DA molar ratio as an index of DA metabolism was similar in the WO and the Dysk patients. However, in the putamen, the ratio of HVA/DA was significantly higher in the WO compared with the Dysk (p = 0.03)and the NMC (p = 0.04) groups of patients. In the putamen, the DOPAC levels were higher in the WO cases while in the Dysk cases, 3-MT levels were higher. The results suggest that in the WO only cases, the putaminal DA was in large measure metabolized intraneuronally while the DA metabolism in our Dysk only patients was mainly extraneuronal. We conclude that the magnitude and the site (intra vs. extraneuronal) of the synaptic DA metabolism in the putamen plays a significant role in LD-induced Dysk and WO.

Increased adenosine A2A receptors in the brain of Parkinson's disease patients with dyskinesias

Brain adenosine A2A receptors have recently attracted considerable attention because of their interaction with the dopaminergic system and as potential targets for Parkinson's disease pharmacotherapy. Post mortem adenosine A2A receptor mRNA and [3H]SCH 58261- specific binding to adenosine A2A receptor were studied in the brain of Parkinson's disease patients using in situ hybridization and receptor binding autoradiography, respectively. Fourteen levodopa-treated Parkinson's disease patients, of which seven developed dyskinesias and seven did not, were compared with nine controls. Nigrostriatal denervation was similar between dyskinetic and non-dyskinetic Parkinson's disease patients, as assessed with catecholamine concentrations and [125I]RTI-121-specific binding to dopamine transporters. A2A receptor mRNA levels (+129%; P < 0.01) and [3H]SCH 58261-specific binding (+32%, P < 0.01) were increased in the putamen (lateral and medial) of dyskinetic patients compared with controls. The increase of adenosine A2A receptor mRNA in dyskinetic Parkinson's disease patients was also significant compared with non-dyskinetic Parkinson's disease patients (+60%; P < 0.05) in the lateral putamen. Moreover, [3H]SCH 58261-specific binding to adenosine A2A receptors was increased in the external globus pallidus (+24%; P < 0.001) of Parkinson's disease patients compared with controls, regardless of the dyskinesigenic response to levodopa. No change of adenosine A2A receptors was observed in the caudate nucleus, whereas adenosine A2A receptor protein and mRNA levels in the internal globus pallidus were not different from background. These findings suggest that increased synthesis of adenosine A2A receptors in striatopallidal pathway neurons is associated with the development of dyskinesias following long-term levodopa therapy in Parkinson's disease.

Nigral glutathione deficiency is not specific for idiopathic Parkinson's disease

The consistent findings of decreased levels of the major antioxidant glutathione in substantia nigra of patients with idiopathic Parkinson's disease (PD) has provided most of the basis for the oxidative stress hypothesis of the etiology of PD. To establish whether a nigral glutathione deficiency is unique to PD, as is generally assumed, or is present in other Parkinsonian conditions associated with nigral damage, we compared levels of reduced glutathione (GSH) in postmortem brain of patients with PD to those with progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). As compared with the controls, nigral GSH levels were decreased in the PD and PSP patient groups (P < 0.05 for PD [-30%], PSP [-21%]), whereas a similar decrease in the MSA patient group did not reach statistical significance (P = 0.078, MSA [-20%]). GSH levels were normal in all examined normal and degenerating extra-nigral brain areas in PSP and MSA. A trend for decreased levels of uric acid (antioxidant and product of purine catabolism) also was observed in nigra of all patient groups (-19 to -30%). These data suggest that glutathione depletion, possibly consequent to overutilisation in oxidative stress reactions, could play a causal role in nigral degeneration in all nigrostriatal dopamine deficiency disorders, and that antioxidant therapeutic approaches should not be restricted to PD.

Levodopa-induced motor complications are associated with alterations of glutamate receptors in Parkinson's disease

Glutamate receptors were studied in the brains of controls and Parkinson's disease (PD) patients, of which 10 of 14 developed motor complications (dyskinesias and/or wearing-off) following levodopa therapy. (125)I-RTI binding to the dopamine transporter and dopamine concentrations show comparable nigrostriatal denervation between the subgroups of PD patients. (3)H-Ro 25-6981 binding to the NR1/NR2B NMDA receptor was increased in the putamen of PD patients experiencing motor complications compared to those who did not (+53%) and compared to controls (+18%) whereas binding remained unchanged in the caudate nucleus. (3)H-AMPA binding was increased in the lateral putamen (+23%) of PD patients with motor complications compared to those without whereas it was decreased in the caudate nucleus of the PD patients (-16%) compared to controls. Caudate and putamen (3)H-CGP39653 binding to NR1/NR2A NMDA receptor and NR1 subunit mRNA levels measured by in situ hybridization were unchanged in subgroups of PD patients compared to controls. These findings suggest that glutamate receptor supersensitivity in the putamen plays a role in the development of motor complications (both wearing-Off and dyskinesias) following long-term levodopa therapy in PD.

Changes of GABA receptors and dopamine turnover in the postmortem brains of parkinsonians with levodopa-induced motor complications

Brain samples from 14 Parkinson's disease patients, 10 of whom developed motor complications (dyskinesias and/or wearing-off) on dopaminomimetic therapy, and 11 controls were analyzed. Striatal 3beta-(4-(125)I-iodophenyl)tropane-2beta-carboxylic acid isopropyl ester ([(125)I]RTI-121) -specific binding to dopamine transporter and concentration of dopamine were markedly decreased, but no association between level of denervation and development of motor complications was observed. The homovanillic acid/dopamine ratio of concentrations was higher in putamen of patients with wearing-off compared to those without. Striatal (35)S-labeled t-butylbicyclophosphorothionate ([(35)S]TBPS) and [(3)H]flunitrazepam binding to GABA(A) receptors were unchanged in patients with Parkinson's disease, whereas [(125)I]CGP 64213 -specific binding to GABA(B) receptors was decreased in the putamen and external segment of the globus pallidus of parkinsonian patients compared with controls. [(3)H]Flunitrazepam binding was increased in the putamen of patients with wearing-off compared to those without. [(35)S]TBPS-specific binding was increased in the ventral internal globus pallidus of dyskinetic subjects. These data suggest altered dopamine metabolism and increased GABA(A) receptors in the putamen related to the pathophysiology of wearing-off. The present results also suggest that an up-regulation of GABA(A) receptors in the internal globus pallidus is linked to the pathogenesis of levodopa-induced dyskinesias.

Progressive supranuclear palsy diagnosis and confounding features: report on 16 autopsied cases

We evaluated 16 (15 men, 1 woman) autopsy-verified progressive supranuclear palsy (PSP) cases during 31 years (1969-2000) for clinical diagnosis and the course of the disease. The onset was gait difficulty or postural instability in 9 (56.3%), general motor slowing in 3 (18.8%), and tremor in 2. One case had onset with cognitive decline and 1 as hemidystonia. Four cases had supranuclear ophthalmoplegia (SNO) at the first assessment and were diagnosed as PSP. By last assessment, PSP diagnosis was made in 4 additional cases, but in 8 (50%) who never manifested ophthalmoplegia (mean 9.8 years after onset), PSP diagnosis was not made. Other manifestations included bulbar symptoms in 13 (81.3%), and cognitive impairment in 10 (62.5%) during the course of illness. Fifteen cases received levodopa, amantadine, anticholinergics, dopamine agonists, and selegiline in different combinations with symptomatic benefit in 9 of 15 (60%). Five had some improvement on levodopa alone and 3 showed more improvement when a dopamine agonist was added to levodopa. In general, the benefit was minimal and occurred only early in the course of illness. The mean age at onset was 63.7 (range, 53-85) years. Mean duration at PSP diagnosis was 4.8 (range, 2-11) years. Mean survival was 8.6 (range, 3-24) years and mean age at death was 72.3 (range, 60-89) years. When the different diagnostic criteria recommended in the literature were used, the accuracy of clinical diagnosis did not improve substantially.

Brain aconitase activity is not decreased in progressive supranuclear palsy

The novel finding of decreased activity of aconitase, a key Krebs cycle enzyme highly sensitive to oxidative damage, in cybrid cell lines using mitochondrial DNA from patients with progressive supranuclear palsy (PSP) implies an enzyme abnormality in brain. However, the authors found that postmortem brain aconitase activity is normal in PSP. This suggests that patients with PSP do not have systemic aconitase deficiency and that data derived from cybrid cell models of neurodegenerative disorders might not always predict similar changes in human brain.

Brain proteasomal function in sporadic Parkinson's disease and related disorders

Because genetic defects relating to the ubiquitin-proteasome system were reported in familial parkinsonism, we evaluated proteasomal function in autopsied brains with sporadic Parkinson's disease. We found that proteasome peptidase activities in a fraction specific to the proteasome were preserved in five brain areas (including the striatum) of Parkinson's disease where neuronal loss is not observed. Striatal protein levels of two proteasome subunits were normal in Parkinson's disease but reduced mildly in disease controls (multiple system atrophy). Our brain data suggest that a systemic, global disturbance in the catalytic activity and degradation ability of the proteasome itself is unlikely to explain the cause of Parkinson's disease.

Progressive supranuclear palsy: clinical features, pathophysiology and management

Progressive supranuclear palsy (PSP) is a degenerative condition of unknown aetiology that produces an akinetic-rigid form of parkinsonism characterised by early falls and abnormalities of extraocular movements. Mean age of onset is approximately 63 years, and mean survival from symptom onset is 9 years. Men are much more frequently affected than women. The classic clinical finding is supranuclear ophthalmoplegia, which may not present until late in the illness, if at all. The clinical diagnosis of PSP can be difficult to make, as the sites of pathology are heterogeneous. Structural and functional neuroimaging studies, although not specific for PSP, may be of some assistance in making the diagnosis. The definitive diagnosis of PSP requires the presence of both clinical and neuropathological evidence. Multiple anatomical sites are affected in PSP. The most consistently involved are the subthalamic nucleus, globus pallidus interna and externa, pontine nuclei, periaqueductal grey matter and the substantia nigra. The location of the pathology accounts for the clinical features. The histological hallmark of PSP is the presence of globose neurofibrillary tangles in the affected subcortical nuclei. Neurofibrillary tangles are composed of abnormally phosphorylated tau, a microtubule-associated protein that is involved in maintenance of the cytoskeleton. Abnormalities near or in the gene coding for tau are implicated in the pathogenesis of PSP. The multiple neurotransmitter abnormalities, including those affecting dopamine, acetylcholine, gamma-aminobutyric acid and norepinephrine (noradrenaline) systems and pathways, as well as both pre- and post-synaptic pathology, make pharmacological therapy of PSP a challenge. Although an individual patient may respond to a drug, in general patients with PSP have a minimal response and a short duration of sustained benefit.

The protective role of levodopa in the human substantia nigra

Laboratory studies and studies of animal models of parkinsonism have produced contradictory evidence, but there is no evidence that LD is toxic to normal substantia nigra in animals. We have studied human subjects longitudinally to address that issue. A cumulative LD dose up to 24 kg was not toxic in one autopsied essential tremor (ET) case. Two other ET patients did not develop parkinsonism on 8.5 kg and 21 kg cumulative LD dose, respectively. One DOPA-responsive dystonia (DRD) case has no evidence of parkinsonism after 29 years and more than 17 kg of LD. A DRD patient who received 3 kg over 11 years had normal SN neuronal complement at autopsy. One patient who has clinical and laboratory evidence of nigral pathology as the basis of parkinsonism when untreated for 18 years had progressive disability. While on LD he has excellent symptomatic benefit and virtual cessation of progression of the disease. Epidemiologic studies indicate that those prescribed LD at an early stage of illness and hence given larger cumulative lifetime doses have longer survival than those in whom LD is started late and who receive smaller total doses. Our observations and the available literature support that levodopa is not toxic to normal or diseased substantia nigra in human beings. Evidence presented here indicates that levodopa has a protective effect on the human substantia nigra neurons.

Increase of preproenkephalin mRNA levels in the putamen of Parkinson disease patients with levodopa-induced dyskinesias

The expression of preproenkephalin messenger RNA was studied in the brain of Parkinson disease (PD) patients using in situ hybridization. All these patients were treated with levodopa (LD) and the development of motor complications was recorded. Eleven normal controls and 14 PD patients were used, of which 4 developed dyskinesias, 3 developed wearing-off, 3 developed both dyskinesias and wearing-off, and 4 developed no adverse effect following dopaminomimetic therapy. Nigrostriatal denervation was similar between the subgroups of PD patients as assessed using 125I-RTI-specific binding to the dopamine transporter and measures of catecholamine concentrations by HPLC. A significant increase of preproenkephalin messenger RNA levels was observed in the lateral putamen of dyskinetic patients in comparison to controls (+210%; p < 0.01) and in comparison to nondyskinetic patients (+112%; p < 0.05). No change was observed in medial parts of the putamen or in the caudate nucleus. No relationship between preproenkephalin messenger RNA levels and other clinical variables such as development of wearing-off, age of death, duration of disease, or duration of LD therapy was found. These findings suggest that increase synthesis of preproenkephalin in the medium spiny output neurons of the striatopallidal pathway play a role in the development of dyskinesias following long-term LD therapy in Parkinson disease.

Elevated levels of DeltaFosB and RGS9 in striatum in Parkinson's disease

INTRODUCTION

In the present study, we determined whether certain proteins known to mediate dopamine signaling in striatum show abnormal levels in Parkinson's disease.

METHODS

Protein levels were assayed by western blotting in samples of caudate nucleus and putamen obtained at autopsy from patients with Parkinson's disease and from control subjects. Levels of several markers of dopaminergic function were also assayed.

RESULTS

Levels of the transcription factor DeltaFosB and of the G protein modulatory protein RGS9 were both increased in caudate and putamen from patients with Parkinson's disease. Levels of several other proteins were not affected. Interestingly, levels of both DeltaFosB and RGS9 correlated inversely with putamen levels of dopamine, dopamine metabolites, and the dopamine transporter.

CONCLUSIONS

These findings are consistent with observations in laboratory animals, which have demonstrated elevated levels of DeltaFosB in striatum after denervation of the midbrain dopamine system, and confirm that similar adaptations in DeltaFosB and RGS9 occur in humans with Parkinson's disease. Knowledge of these adaptations can help us understand the changes in striatal function associated with Parkinson's disease and assist in the development of novel treatments.

Levodopa prolongs life expectancy and is non-toxic to substantia nigra

The primary objective of the study was to determine the effect of levodopa (LD) on human substantia nigra. The study included patients seen at the Movement Disorder Clinic, Saskatoon over a 32 year period. The evidence provided is based on epidemiological observations of 934 consecutive Parkinson syndrome (PS) patients assessed during 22 years and detailed studies of six patients including two autopsies. Life expectancy increased significantly with LD therapy. The prolonged survival was evident when the patients were treated during early stage of the illness. One parkinsonian patient with substantia nigra (SN) pathology who was extensively studied for 30 years, revealed significant slowing of the disease progression while on LD. Three essential tremor patients who received 24 kg (26 years), 22 kg (21.5 years), and 8.5 kg (12.5 years) LD respectively, had no evidence of PS and one autopsy revealed normal SN. Two dopa-responsive dystonia patients who received LD 3 kg (11 years) and 17 kg (29 years) each had no evidence of PS and one autopsy revealed normal number of SN neurons. These observations indicate that LD is not toxic to human SN and are consistent with salutary effect of the drug on the SN in Parkinson's disease.

A randomized, double masked, controlled trial of botulinum toxin type A in essential hand tremor

OBJECTIVE

To evaluate the safety and efficacy of botulinum toxin type A injection in essential tremor of the hand.

BACKGROUND

Botulinum toxin type A is an effective treatment for dystonia, spasticity, and other movement disorders and has been found to be useful in open-label studies and one double-masked study of essential hand tremor.

METHODS

One hundred thirty-three patients with essential tremor were randomized to low-dose (50 U) or high-dose (100 U) botulinum toxin type A (Botox) or vehicle placebo treatment. Injections were made into the wrist flexors and extensors. Patients were followed for 16 weeks. The effect of treatment was assessed by clinical rating scales, measures of motor tasks and functional disability, and global assessment of treatment. Hand strength was evaluated by clinical rating and by a dynamometer.

RESULTS

Both doses of botulinum toxin type A significantly reduced postural tremor on the clinical rating scales after 4 to 16 weeks. However, kinetic tremor was significantly reduced only at the 6-week examination. Measures of motor tasks and functional disability were not consistently improved with botulinum toxin type A treatment. Grip strength was reduced for the low- and high-dose botulinum toxin type A groups as compared with the placebo group. Adverse reactions consisted mainly of dose-dependent hand weakness.

CONCLUSION

Botulinum toxin type A injections for essential tremor of the hands resulted in significant improvement of postural, but not kinetic, hand tremors and resulted in limited functional efficacy. Hand weakness is a dose-dependent significant side effect of treatment at the doses used in this study.

Elevated activity of phospholipid biosynthetic enzymes in substantia nigra of patients with Parkinson's disease

We reported that the activities of phospholipase A2, phosphocholine cytidylyltransferase and phosphoethanolamine cytidylyltransferase, key phospholipid metabolic enzymes, are low in substantia nigra of normal human brain and that this might reduce the ability of nigral neurons to repair damage to cell membranes. To determine whether adaptive changes in nigral phospholipid metabolism can occur in idiopathic Parkinson's disease we compared activities of 11 catabolic and anabolic enzymes in autopsied brain of 10 patients with Parkinson's disease to those in control subjects. Nigral activity of the catabolic enzyme phospholipase A2 was normal in the Parkinson's disease group, whereas that of the biosynthetic enzymes phosphoethanolamine cytidylyltransferase, phosphocholine cytidylyltransferase, and phosphatidylserine synthase were elevated 193, 48 and 38%, respectively, possibly representing a compensatory response to repair membrane phospholipids. Enzyme activities were normal in all other brain areas with the exception of increased (+26%) activity of calcium-stimulated phospholipase A2 in putamen, a change which could be consequent to either decreased dopaminergic striatal input or to a dopamine nerve terminal degenerative process. Our data indicate that the normally low rate of membrane phospholipid synthesis in the substantia nigra, the primary area of neurodegeneration in Parkinson's disease, is increased during the course of the disorder. We suggest that pharmacotherapies which augment this compensatory response might have utility as a treatment for Parkinson's disease.

The evolution of diagnosis in early Parkinson disease. Parkinson Study Group

CONTEXT

Since there is no diagnostic biological marker for Parkinson disease (PD), the diagnosis is based on the results of clinical assessment. The accuracy of diagnosis improves with time and repeated assessments. Studies that require only inclusion of early cases of PD present a diagnostic challenge. Previous studies concluded that initial diagnoses of PD made by general neurologists were incorrect in 24% to 35% of the cases when patients were examined at autopsy. Experts in movement disorders are expected to have greater accuracy of initial diagnosis of PD.

OBJECTIVE

To determine the evolution of clinical diagnosis in patients with early PD made initially by experts in PD.

DESIGN

Eight hundred patients with mild parkinsonian symptoms (Hoehn and Yahr stage 1 or 2) who received a diagnosis of PD less than 5 years before the beginning of the study were included in the original Deprenyl and Tocopherol Antioxidative Therapy for Parkinson's Disease study. These patients were followed up prospectively with repeated clinical assessments. The following clinical criteria were used to reassess the initial diagnosis: investigator's confidence in the diagnosis of PD, presence of atypical clinical features, findings of imaging studies, response to levodopa, and results of autopsy examinations.

RESULTS

The mean +/- SD duration of illness in the 800 cases at enrollment was 2.2+/-1.3 years, and the mean +/- SD Hoehn and Yahr stage was 1.6+/-0.5. The mean +/- SD follow-up was 6.0+/-1.4 years (range, 0.2-7.6 years). In 5 cases, PD was not confirmed at autopsy, and in 15 patients, the results of imaging studies indicated the presence of other pathological conditions. Of the 550 cases treated with levodopa, 49 (8.9%) had little or no improvement; 6 of these cases overlap with either autopsy or imaging study exclusion criteria. Two other cases had at least 4 of the 6 atypical clinical features arguing against the diagnosis of PD. Thus, of the 800 patients, 65 (8.1%) did not have PD according to the study criteria. Compared with those patients with the final diagnosis of PD, in the diagnoses of 60 patients without autopsy, the duration of symptoms (mean +/- SD, 7.2+/-2.0 years vs. 8.3+/-1.9 years; P<.001) and the duration of follow-up (5.3+/-1.6 years vs. 6.1+/-1.3 years; P<.001) were shorter.

CONCLUSIONS

We found that 65 (8.1%) of patients initially diagnosed as having PD were later found to have an alternate diagnosis based on multifactorial clinical diagnostic criteria. This alternate diagnosis indicated that experts in PD changed their diagnoses infrequently during the 7.6-year follow-up.

Striatal biopterin and tyrosine hydroxylase protein reduction in dopa-responsive dystonia

OBJECTIVE

To determine the mechanism leading to striatal dopamine (DA) loss in dopa-responsive dystonia (DRD).

BACKGROUND

Although mutations in the gene GCH1, coding for the tetrahydrobiopterin (BH4) biosynthetic enzyme guanosine triphosphate-cyclohydrolase I, have been identified in some patients with DRD, the actual status of brain BH4 (the cofactor for tyrosine hydroxylase [TH]) is unknown.

METHODS

The authors sequenced GCH1 and measured levels of total biopterin (BP) and total neopterin (NP), TH, and dopa decarboxylase (DDC) proteins, and the DA and vesicular monoamine transporters (DAT, VMAT2) in autopsied brain of two patients with typical DRD.

RESULTS

Patient 1 had two GCH1 mutations but Patient 2 had no mutation in the coding region of this gene. Striatal BP levels were markedly reduced (<20% of control subjects) in both patients and were also low in two conditions characterized by degeneration of nigrostriatal DA neurons (PD and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treated primate), whereas brain NP concentrations were selectively decreased (<45%) in the DRD patients. In the putamen, both DRD patients had severely reduced (<3%) TH protein levels but had normal concentrations of DDC protein, DAT, and VMAT2.

CONCLUSIONS

The data suggest that 1) brain BH4 is decreased substantially in dopa-responsive dystonia, 2) dopa-responsive dystonia can be distinguished from degenerative nigrostriatal dopamine deficiency disorders by the presence of reduced brain neopterin, and 3) the striatal dopamine reduction in dopa-responsive dystonia is caused by decreased TH activity due to low cofactor concentration and to actual loss of TH protein. This reduction of TH protein, which might be explained by reduced enzyme stability/expression consequent to congenital BH4 deficiency, can be expected to limit the efficacy of acute BH4 administration on dopamine biosynthesis in dopa-responsive dystonia.

Tolcapone improves motor function in parkinsonian patients with the "wearing-off" phenomenon: a double-blind, placebo-controlled, multicenter trial

We studied the new catechol-O-methyltransferase inhibitor tolcapone, 100 and 200 mg, three times daily (tid) in a randomized, double-blind, parallel-group trial involving 202 parkinsonian patients who were experiencing the "wearing-off" phenomenon on levodopa therapy. After 3 months, patients receiving tolcapone had a significant decrease in mean daily levodopa dose requirement compared with placebo-treated patients (p < 0.01). In patients treated with tolcapone 200 mg tid, daily "off" time, measured using patient diaries, was reduced from baseline by 3.25 hours; this reduction was significantly different from that seen in the placebo group (p < 0.01). Moreover, the number of daily levodopa intakes was reduced significantly in each tolcapone group compared with placebo (p < 0.01). We found significant improvements in motor function and overall efficacy in the tolcapone groups (p < 0.01). The most frequent adverse events were associated with levodopa treatment. Dyskinesia developed or worsened in 18% of patients receiving placebo, in 51% receiving tolcapone 100 mg tid, and in 64% receiving 200 mg tid, with most cases occurring within the first 30 days of the study. Diarrhea was the most frequent nondopaminergic event, occurring in 14% on placebo, 13% on tolcapone 100 mg tid, and 19% on 200 mg tid. Overall 18% of patients withdrew because of adverse events: 15% on placebo, 17% on tolcapone 100 mg tid, and 22% on 200 mg tid. We conclude that tolcapone as an adjunct offers promise for the relief of the "wearing-off " phenomenon in levodopa-treated parkinsonian patients.

Distal hereditary upper limb muscular atrophy

OBJECTIVES

To identify the clinical, electrophysiological, and genetic characteristics of a family with an unusual form of hereditary motor neuron disease.

METHODS

Surviving members of a pedigree in which affected members presented with weakness and atrophy of distal musculature in the upper limbs were examined clinically and electrophysiologically, and had genetic testing.

RESULTS

The disease was autosomal dominantly inherited and manifested as weakness and atrophy of distal musculature in the upper limbs, with minimal involvement of lower limbs, brisk reflexes, minimal sensory findings, and considerable variability in severity among the affected persons. Nerve conduction studies disclosed near normal motor conduction velocity, reduced motor compound action potential amplitude, prolonged distal motor latency, prolonged sensory latency, and normal sensory compound action potential amplitude. Needle electrode examination showed reduced number and increased size of motor unit potentials, but no fibrillations or fasciculations.

CONCLUSION

Distal upper limb muscular atrophy is a distinct clinical entity.

Tolcapone improves motor function in parkinsonian patients with the "wearing-off" phenomenon: a double-blind, placebo-controlled, multicenter trial

We studied the new catechol-O-methyltransferase inhibitor tolcapone, 100 and 200 mg, three times daily (tid) in a randomized, double-blind, parallel-group trial involving 202 parkinsonian patients who were experiencing the "wearing-off" phenomenon on levodopa therapy. After 3 months, patients receiving tolcapone had a significant decrease in mean daily levodopa dose requirement compared with placebo-treated patients (p < 0.01). In patients treated with tolcapone 200 mg tid, daily "off" time, measured using patient diaries, was reduced from baseline by 3.25 hours; this reduction was significantly different from that seen in the placebo group (p < 0.01). Moreover, the number of daily levodopa intakes was reduced significantly in each tolcapone group compared with placebo (p < 0.01). We found significant improvements in motor function and overall efficacy in the tolcapone groups (p < 0.01). The most frequent adverse events were associated with levodopa treatment. Dyskinesia developed or worsened in 18% of patients receiving placebo, in 51% receiving tolcapone 100 mg tid, and in 64% receiving 200 mg tid, with most cases occurring within the first 30 days of the study. Diarrhea was the most frequent nondopaminergic event, occurring in 14% on placebo, 13% on tolcapone 100 mg tid, and 19% on 200 mg tid. Overall 18% of patients withdrew because of adverse events: 15% on placebo, 17% on tolcapone 100 mg tid, and 22% on 200 mg tid. We conclude that tolcapone as an adjunct offers promise for the relief of the "wearing-off" phenomenon in levodopa-treated parkinsonian patients.

Concordance of common movement disorders among familial cases

Multicase families are frequently utilized in studies of movement disorders (MDs). We report families with two or more MD cases seen at the Movement Disorder Clinic, Saskatoon (MDCS). In 30% of the MD probands, there was either a history or documentation of at least one secondary MD case in the family. Only those MD cases that were seen at the MDCS were considered in this study. A total of 56 probands and 77 secondary MD cases were seen at the MDCS between 1968 and 1996. In 24 (31.2%) of the secondary cases, the diagnosis was different from that in the proband. In 46 families (82%), only one secondary case was seen, and the diagnosis was concordant with the proband in 71.7%. In the remaining 10 families with two or more secondary cases, the diagnosis was concordant in 64.5% of cases. The largest subgroup was Parkinson's disease (PD)--40 probands and 53 secondary cases. of these secondary cases, 73.6% had PD. The concordance rate was 91% in essential tremor, but only 12.5% if the proband had essential tremor + parkinsonism. Considering that a large proportion of secondary cases have a diagnosis discordant with the proband, we recommend that, whenever possible, MD diagnosis in secondary cases be based on clinical assessment.

Is levodopa toxic to human substantia nigra?

Levodopa (LD) is the most effective drug for symptomatic control of Parkinson's disease, but has been suspected to be toxic to substantia nigra (SN) dopaminergic neurons. Tissue culture and animal studies of LD toxicity have produced contradictory evidence, and one study reported that a human subject exposed to a large cumulative dose (cd) of LD over 4 years had no evidence of SN damage. We report the cases of five patients, each of whom received a large cd of LD over a long period. Fluorodopa positron-emission tomography performed in one case indicated parkinsonism. Autopsies in two cases indicated a normal SN in one and a hypopigmented SN with normal cell complement in the other. Three patients had essential tremor, one had nonprogressive parkinsonism, and one had dopa-responsive dystonia. LD (without decarboxylase inhibitor) was administered over 21 years (cd = 21.99 kg), 9 years (cd = 6.6 kg), 26 years (cd = 18.7 kg), 11 years (cd = 3 kg), and 26 years (cd = 23.93 kg), respectively. None of the patients with essential tremor developed clinical features of parkinsonism that indicated significant SN damage, and one had a normal SN at autopsy. The parkinsonian patient displayed no detectable acceleration of disease process, and the patient with dopa-responsive dystonia had a normal complement of SN neurons at autopsy. We conclude that LD, administered at a dose commonly used for treating Parkinson's disease, was not toxic to SN neurons in these cases.

Amantadine: an antiparkinsonian agent inhibits bovine brain 60 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase isozyme

The effect of amantadine (an antiparkinsonian agent) on calmodulin-dependent cyclic nucleotide phosphodiesterase isozymes was investigated. Amantadine inhibited bovine brain 60 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase but not the bovine brain 63 kDa, heart and lung calmodulin-dependent cyclic nucleotide phosphodiesterase isozymes. The inhibition of bovine brain 60 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase was overcome by increasing the concentration of calmodulin. This suggests that amantadine may be an antagonist of calmodulin or act specifically and reversibly on the action of calmodulin. The bovine brain 60 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase isozyme is predominantly expressed in the brain and its inhibition may result in increased intracellular levels of cyclic AMP (cAMP). The increased intracellular levels of cAMP have a protective role for dopaminergic neurons. The present findings suggest that amantadine may be a valuable tool to investigate the physiological role of 60 kDa calmodulin-dependent cyclic nucleotide phosphodiesterase isozyme in the progression of Parkinson's disease and gives a new insight into the action of this drug.

Ophthalmoplegia and leg myorhythmia in Whipple's disease: report of a case

Whipple's disease (WD) is a rare disorder that is more common in males than in females. Progressive supranuclear ophthalmoplegia (SNO) in conjunction with oculomasticatory myorhythmia (OMM) or oculofacioskeletal myorhythmia are characteristic movement abnormalities when WD involves the nervous system. Limb myorhythmia without facial or ocular myorhythmia has not been reported in WD. We report such a case who had SNO and leg myorhythmia but no facial or ocular myorhythmia. She had onset of WD at age 28 and 16 years later developed SNO and leg myorhythmia. The neurological manifestations did not respond to antimicrobial agents or to the drugs used for parkinsonism or essential tremor. Valproate produced a remarkable improvement in leg myorhythmia, but the efficacy declined after 3 months. Because WD may infest as a neurological disorder without gastrointestinal symptoms, all SNO cases, with or without OMM, and those with skeletal myorhythmia should be suspected of WD. These patients should be treated vigorously and followed carefully since neurological involvement is the most disabling feature and it has a propensity to relapse.

Inhibition of bovine brain calmodulin-dependent cyclic nucleotide phosphodiesterase isozymes by deprenyl

Intracellular concentrations of cyclic nucleotides is regulated by cyclic nucleotide phosphodiesterases and calmodulin-dependent cyclic nucleotide phosphodiesterases (CaMPDE), one of the most intensively studied and best characterized phosphodiesterases. In the present study, the effect of an antiparkinsonian agent, deprenyl (selegeline hydrochloride) which is believed to be a selective inhibitor of monoamine oxidase-B, on bovine brain calmodulin-dependent cyclic nucleotide phosphodiesterase (CaMPDE) isozymes have been investigated. The findings indicated that deprenyl inhibited brain 60 kDa isozyme, however the inhibition for brain 63 kDa CaMPDE was observed to a lesser extent. The inhibition of brain 60 kDa CaMPDE was overcome by increasing the concentration of calmodulin suggesting that deprenyl may be calmodulin antagonist or act specifically and reversibly on the action of calmodulin. The 60 kDa CaMPDE isozyme is predominantly expressed in brain and its inhibition can result in increased intracellular levels of cAMP. The increased intracellular levels of cAMP have a protective role for dopaminergic neurons. Therefore, deprenyl may be a valuable tool to investigate the physiological roles of brain CaMPDE isozymes in progression of Parkinson's disease and gives a new insight into the action of this drug.

Amantadine treatment is an independent predictor of improved survival in Parkinson's disease

Amantadine has been used for more than 20 years in the symptomatic treatment of Parkinson's disease (PD). Several recent discoveries suggest that amantadine could also have a neuroprotective effect in PD. We studied survival in all parkinsonism (including PD and other parkinsonian syndromes) patients attending a single clinic, employing standard survival curves and a Cox regression model, to identify independent predictive variables for survival (while taking into account factors potentially associated with both outcome and treatment selection). Amantadine-treated patients (n = 250) were similar to the patients not treated with amantadine (n = 586) in terms of age, gender, type of parkinsonism, Hoehn and Yahr stage and dementia status at initial neurological visit. Amantadine use was an independent predictor of improved survival (p < 0.01). Improved survival was also associated with a higher 10-year expected survival (based on age, gender, and birth year), absence of dementia, type of parkinsonism = PD, and low Hoehn and Yahr stage (I or II) at initial neurologic visit (all p < 0.01); these additional factors occurred in statistically similar proportions in the groups that were and were not treated with amantadine. The association of improved survival with amantadine use may stem from symptomatic benefit or may reflect a "neuroprotective" effect, mediated through N-methyl-D-aspartate (NMDA) receptor antagonism, dopamine uptake blockade activity, or other mechanisms. Our preliminary findings suggest that a prospective, controlled, randomized trial of amantadine's effects on PD progression is warranted.

GTP-cyclohydrolase I gene mutations in hereditary progressive amd dopa-responsive dystonia

Recently, mutations of the GTP-cyclohydrolase I (GTP-CH I) gene, which catalyzes the first step in the tetrahydrobiopterin (BH4) biosynthesis, were discovered in Japanese patients with hereditary progressive dystonia/dopa-responsive dystonia (HPD/DRD). However, it has not been confirmed that non-Japanese patients also contain mutations in the same gene, or whether these mutations are specific to HPD/DRD. In this study, two novel nonsense mutations in exon I of the GTP-CH I gene and a new mutation at the splice acceptor site of intron I were identified in an autopsied case of English-Irish descent and 2 Japanese patients with HPD/DRD. In the latter, cerebrospinal fluid (CSF) neopterin levels (which may reflect the GTP-CH I activity in the brain) were reduced to 18% and 37% of controls. A therapeutic trial of oral BH4 was ineffective, however, in a genetically proven patient. In contrast, no mutations in any exons of the GTP-CH I gene were found in 2 patients with early-onset parkinsonism with dystonia (EOP-D) who developed dopa-responsive parkinsonism and dystonia at 6 and 8 years old, respectively. Neopterin levels in CSF were well preserved in 6 EOP-D patients. These data suggest that, among patients of different racial backgrounds, the pathogenesis of HPD/DRD, unlike EOP-D, involves partial reduction of the brain GTP-CH I activity consequent to mutations in the GTP-CH I gene. Measurement of CSF neopterin concentration may be useful for the differential diagnosis between HPD/DRD and EOP-D.

Prevalence of movement disorders in institutionalized elderly

The proportion of the population over age 65 years is steadily increasing in Canada and the elderly who are unable to live independently are frequently institutionalized in chronic care facilities. We report our observations on movement disorders (MD) in an institutionalized elderly population of Saskatchewan. A representative sample of 67 subjects aged > or = 65 years had a detailed neurological evaluation on three separate occasions. MD were detected in 13 (19%) cases. The majority, 11 (16%), were females. Seven (10%) had essential tremor, 4 (6%) Parkinson's disease and 2 (3%) had drug-induced parkinsonism.