Parkinsonism and neurofibrillary tangle pathology in pigmented nuclei

Amyotrophic Lateral Sclerosis, Parkinson’s Disease and Alzheimer’s Disease: Phylogenetic Disorders of the Human Neocortex Sharing Many Characteristics

Features common to amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD) and Alzheimer’s disease (AD) are reviewed. Shared epidemiological aspects include an increasing frequency which is proportional for each disease. We draw attention to geographic non-uniform distribution which, for ALS and PD, correlates positively with latitude. Clinical and pathological overlap occurs in the same patients, and in members of the same family. A high early morning plasma cysteine/sulphate ratio possibly related to the development of proteinacious inclusions, as well as ubiquinated neuronal inclusions, characterize ALS, PD and AD. HLA-DR (the human group II major histocompatibility class) staining is marked in ALS, PD and AD and may represent autoimmunity-incited by-products of neuronal degeneration. Based upon demonstrated glutaminergic connections between the neocortex and anterior horn cells, the entorhinal cortex and the basal ganglia we hypothesize that ALS, AD and PD are phylogenetic disturbances of the neocortical cell. The postsynaptic neuron may degenerate secondarily to anterograde effects of deranged glutamate metabolism. Future therapeutic strategies should be directed to agents that decrease transmission induced by excitatory amino-acids.

Amyotrophic lateral sclerosis with dementia showing clinical parkinsonism and severe degeneration of the substantia nigra: Report of an autopsy case

An autopsy case of amyotrophic lateral sclerosis with dementia (ALS-D) showing clinically overt parkinsonism and severe degeneration of the substantia nigra is reported. The patient was a 78-year-old man who died after a 2-year clinical course characterized by parkinsonism that was responsive to Levodopa (L-DOPA) treatment. Motor neuron symptoms and dementia were not apparent ante-mortem. The autopsy demonstrated the severe degeneration of the substantia nigra without alpha-synucleinopathy-related changes. Finely granular mineralization of necrotic neurons was a unique finding in the substantia nigra. The mild loss of spinal anterior horn cells, the appearance of several Bunina bodies and the degeneration of the hippocampal subiculum and temporal cortex were also noted. A small number of ubiquitinated intra-cytoplasmic inclusions were found in neurons of the dentate fascia of the hippocampus and the temporal and frontal cortices. Although the degeneration of the substantia nigra is a common finding in ALS-D, patients seldom develop clinically overt parkinsonism. This case indicates that patients with ALS-D rarely present with predominantly parkinsonian clinical features and these symptoms and signs can be improved by L-DOPA treatment.

Autosomal dominant parkinsonism associated with variable synuclein and tau pathology

Since the original 1995 report of a parkinsonian kindred, four individuals have been affected (mean age at onset, 65 years). All four had cardinal signs of Parkinson disease (PD) and good response to levodopa. Four autopsies showed neuronal loss and gliosis in the substantia nigra. Lewy bodies (LB) limited to brainstem nuclei were detected in one case, diffuse LB in the second, neurofibrillary tangles (NFT) without LB in the third, and neither NFT nor LB in the fourth. Genetic studies suggested linkage to the PARK8 locus on chromosome 12.

The neuromythology of Parkinson's Disease

Over the last century three central points have become the orthodox dogma accepted and taught by those who study Parkinson's Disease. These are: Parkinson's Disease is one disease. Lewy bodies in the substantia nigra are an acceptable hallmark of Parkinson's Disease. Lewy bodies are responsible for the death of nigral neurons in Parkinson's Disease. Each of these tenets now present difficulties, and we are beginning to enter an era in which we must look critically at the current evidence to decide whether each dictum can be sustained.

Genetics of parkin-linked disease

Research into Parkinson's disease (PD), once considered the archetypical non-genetic neurodegenerative disorder, has been revolutionized by the identification of a number of genes, mutations of which underlie various familial forms of the disease. Whereas such mutations appear to exist in a relatively small number of individuals from a few families, the study of the function of these genes promises to reveal the fundamental disease pathogenesis, not only of familial forms of the disease, but also of the much more common sporadic PD. The observation that mutations in the second identified PD locus (parkin) are common in juvenile- and early-onset PD and increasing evidence supporting a direct role for parkin in late-onset disease make this gene a particularly compelling candidate for intensified investigation. The determination of the frequency and effect of parkin mutations in various subsets of PD will be crucial for understanding the way in which parkin is related to neurodegenerative mechanisms, and whether these subsets might be effectively identified and treated. In addition, many aspects of parkin-linked disease, originally thought to be well defined, have now been obscured both by genetic studies that preclude a simple model of disease transmission and by clinical and pathological studies that demonstrate broad variability in cases with parkin mutations. Future studies that address the issues in question should have a far-reaching impact in downstream biochemical studies and our understanding of parkin's role in PD.

Parkinson's syndrome associated with neurofibrillary degeneration and tau pathologic findings

Several distinct clinical syndromes presenting with parkinsonism have been associated with subcortical neurofibrillary degeneration and the abnormal accumulation of hyperphosphorylated tau protein in the brain. Mutations of tau have been linked with a small number of autosomal dominantly inherited families who present with frontolimbic cognitive deficits, behavioural disorders, and Parkinson's syndrome. Some of the sporadic disorders (progressive supranuclear palsy [PSP] and corticobasal degeneration) have been referred to by molecular pathologists as primary tauopathies, implicating abnormalities of tau in their pathogenesis. We have identified a sporadic parkinsonian syndrome characterised by bradykinesia, a variable response to levodopa, and a mean duration of disease of 9 years, which resembles bodig (Parkinson's-dementia of Guam), and histologically has close similarities with both PSP and postencephalitic parkinsonism. Further characterisation of these cases frequently confused with Parkinson's disease may broaden the clinical spectrum of parkinsonian disorders linked with neurofibrillary tangle formation.

Pathological, clinical and genetic heterogeneity in progressive supranuclear palsy

We have identified two groups of patients with clinically typical and atypical, pathologically diagnosed progressive supranuclear palsy (PSP), and investigated their genetic and molecular pathological characteristics. Those with clinically typical PSP are more likely to have the PSP susceptibility genotype and to have the deposition of PSP-type hyperphosphorylated tau protein. The clinically atypical PSP group contains a number of different clinical syndromes, including an L-dopa unresponsive bradykinetic syndrome and a clinical syndrome closely resembling idiopathic Parkinson's disease. The clinically atypical PSP group are less likely to have the PSP susceptibility genotype and often have the deposition of Alzheimer's disease paired helical filament type hyperphosphorylated tau. This study suggests that the tau PSP susceptibility genotype is most strongly associated with clinically typical PSP. Neurofibrillary tangle parkinsonian disorders, which pathologically resemble PSP but involve the deposition of Alzheimer's disease-type tau often without involvement of the tau susceptibility genotype, need to be distinguished for diagnostic and research purposes.

Clinical-pathological study of levodopa complications

We sought to determine the continued benefit and the pattern of motor complications of long-term levodopa treatment in Parkinson's disease. Patients were evaluated between 1968 and 1996. Only those who had an adequate levodopa trial and in whom autopsy revealed Lewy body Parkinson's disease were included. Total levodopa and mean daily dose were calculated in each case. Dyskinesia, wearing-off and on-off were collectively classified as motor adverse effects and reported as cumulative incidence. Forty-two patients (male, 30; female, 12) with mean 15.9 years of illness and 9.1 years follow-up received on average 500-mg levodopa daily over 9.8 years. Seventeen of 21 patients assessed during the last 18 months of life reported some motor benefit. Adverse effects were seen in 71.4% of patients. The most common was dyskinesia, in 61.9%; wearing-off in 35.7%; and on-off in 16.7% of patients. The earliest adverse effect was dyskinesia and the last to emerge was on-off. Isolated dyskinesia was seen in 35.7% and wearing-off in 7.1% of patients; 15.5% of patients developed dyskinesia after 2.6 years and 31% after 6.4 years on levodopa. We concluded that levodopa benefit declined and adverse effects increased with time. Dyskinesia was the earliest and the most common isolated adverse effect.

Genetics of Parkinson's disease

Here we review familial Parkinson's disease from clinical, as well as molecular genetic aspects. To date, two genes responsible for familial Parkinson's disease have been identified: one is the alpha-synuclein gene located in the long arm of chromosome 4, and the other is the parkin gene located in the long arm of chromosome 6. The mode of inheritance of the former is autosomal dominant and clinical features consist of levodopa-responsive parkinsonism; the age of onset is younger than that of the sporadic cases (in their 40s), and the progression is faster (average disease duration approximately nine years). The latter form is transmitted as an autosomal recessive, and clinical features consist of early onset (in their 20s), levodopa-responsive parkinsonism, and a slow progression of the disease. In addition, the tau gene has been shown to be the disease gene for familial frontotemporal dementia and parkinsonism linked to chromosome 17. There are many other clinical phenotypes of familial Parkinson's disease among which three forms have been mapped to certain chromosome loci: one is in the short arm of chromosome 2, the two other forms are in the different loci of the short arm of chromosome 4. All of them are transmitted as autosomal dominant traits manifesting levodopa responsive parkinsonism. There still exists however, other clinical phenotypes of chromosome loci which are not known. Molecular cloning of these familial Parkinson's disease genes and the elucidation of the functions of the proteins encoded will certainly contribute greatly to the investigation of the etiology and pathogenesis of more common sporadic form of Parkinson's disease.

Amine accumulation: a possible precursor of Lewy body formation in Parkinson's disease

It is now well recognized that the hypothalamus is an important site of neuropathology in Parkinson's disease (PD). Lewy bodies, a marker of nerve cell degeneration and a pathological hallmark of PD, have been observed frequently in the hypothalamus of PD patients by Lewy (1923) and other investigators and confirmed by more recent systematic studies by Langston & Forno (1978). Both Lewy and Langston & Forno found a predilection of Lewy body formation in specific hypothalamic nuclei with the tuberomammillary, lateral, and posterior areas containing by far the highest average counts per nucleus. Selective vulnerability of the tuberomammillary, lateral, and posterior hypothalamic cell groups to degeneration has been observed also in aging, postencephalitic Parkinsonism, Alzheimer's disease, and schizophrenia. The susceptibility of these particular nuclei to degenerative changes including Lewy body formation is not presently understood nor are the mechanisms by which Lewy bodies are formed in PD and other CNS disorders. Accumulation of amines, a pathological process which follows degeneration of catecholamine-containing neurons in experimental animals, also occurs most frequently in the lateral and posterior hypothalamic areas. In the present communication we propose that in PD, amine accumulation may be a precursor to Lewy body formation and that the susceptibility of certain hypothalamic areas to Lewy body formation may be related to their propensity to accumulate amines. Furthermore, the frequent co-existence of Lewy bodies and Alzheimer's neurofibrillary tangles in the lateral and posterior hypothalamic nuclei suggest that they may share a common pathogenetic etiology. If confirmed, this hypothesis may provide an experimental model by which the formation of Lewy bodies and neurofibrillary tangles may be investigated.

Accuracy of clinical diagnosis in parkinsonism--a prospective study

Clinical diagnosis of Parkinson's syndrome (PS) is reasonably easy in most cases but the distinction between different variants of PS may be difficult in early cases. The correct diagnosis is not only important for counselling and management of patients but also in conducting pharmacological and epidemiological studies. There is very little critical literature on the pathological verification of the clinical diagnosis in PS. We report our 22 years experience to address that issue. Between 1968 and 1990, 65 PS patients came to autopsy. Complete data are available in 59 (M-50, F-19) cases. The initial diagnosis made by a qualified neurologist was idiopathic Parkinson's disease (IPD) in 43 cases. Of those 28 (65%) had Lewy body pathology. After a mean duration of 12 years the final diagnosis was IPD in 41 cases which was confirmed in 31 (76%). The IPD could not be clinically distinguished from cases with severe substantia nigra neuronal loss without inclusions or from those with neurofibrillary tangle inclusions and neuronal loss at the anatomical sites typically involved in IPD. All progressive supra-nuclear palsy, olivopontocerebellar atrophy, Jakob-Creutzfeldt's disease and the majority of the multiple system atrophy cases were diagnosed correctly during life. The correct clinical diagnosis in most non-IPD variants of PS was possible within 5 years of onset (range: 2 months to 18 years). We recommend that studies aimed at including only the IPD cases restrict the enrollment to those cases that have had PS motor manifestations for five years or longer duration.

The relationship between Alzheimer's disease, Parkinson's disease and motor neuron disease

We argue against the dominant status assigned to conventional microscopy in the categorization of disorders such as Alzheimer's disease, Parkinson's disease and ALS. As an example we criticize the emphasis that has been placed on correlating the presence of Lewy bodies with the diagnosis of Parkinson's disease. In essence, we submit that Parkinson's disease can exist without Lewy bodies, and Lewy bodies can exist without Parkinson's disease. Nevertheless, we consider that the newer techniques available to histology have led to an important concept that constitutes a shared feature for Alzheimer's disease. Parkinson's disease and ALS; they are all characterized by the deposition of cytoskeletal debris in tissue, so they may perhaps be collectively termed the "Cytoskeletal Disorders".