Sick individuals and sick populations

A classic...

http://ije.oxfordjournals.org/content/14/1/32.long

Int J Epidemiol. 1985 Mar;14(1):32-8.

Rose G.

Abstract

Aetiology confronts two distinct issues: the determinants of individual cases, and the determinants of incidence rate. If exposure to a necessary agent is homogeneous within a population, then case/control and cohort methods will fail to detect it: they will only identify markers of susceptibility. The corresponding strategies in control are the 'high-risk' approach, which seeks to protect susceptible individuals, and the population approach, which seeks to control the causes of incidence. The two approaches are not usually in competition, but the prior concern should always be to discover and control the causes of incidence.

The clinical characteristics of dementia with Lewy bodies and a consideration of prodromal diagnosis

PREDICT-DLB???...

http://alzres.com/content/6/4/46

Alzheimers Res Ther. 2014 Jul 21;6(4):46. eCollection 2014.

Donaghy PC, McKeith IG.

Abstract

Dementia with Lewy bodies (DLB) is the second most common type of degenerative dementia following Alzheimer's disease (AD). DLB is clinically and pathologically related to Parkinson's disease (PD) and PD dementia, and the three disorders can be viewed as existing on a spectrum of Lewy body disease. In recent years there has been a concerted effort to establish the phenotypes of AD and PD in the prodromal phase (before the respective syndromes of cognitive and motor impairment are expressed). Evidence for the prodromal presentation of DLB is also emerging. This paper briefly reviews what is known about the clinical presentation of prodromal DLB before discussing the pathology of Lewy body disease and how this relates to potential biomarkers of prodromal DLB. The presenting features of DLB can be broadly placed in three categories: cognitive impairment (particularly nonamnestic cognitive impairments), behavioural/psychiatric phenomena (for example, hallucinations, rapid eye movement sleep behaviour disorder (RBD)) and physical symptoms (for example, parkinsonism, decreased sense of smell, autonomic dysfunction). Some noncognitive symptoms such as constipation, RBD, hyposmia and postural dizziness can predate the onset of memory impairment by several years in DLB. Pathological studies of Lewy body disease have found that the earliest sites of involvement are the olfactory bulb, the dorsal motor nucleus of the vagal nerve, the peripheral autonomic nervous system, including the enteric nervous system, and the brainstem. Some of the most promising early markers for DLB include the presence of RBD, autonomic dysfunction or hyposmia, 123I-metaiodobenzylguanidine cardiac scintigraphy, measures of substantia nigra pathology and skin biopsy for α-synuclein in peripheral autonomic nerves. In the absence of disease-modifying therapies, the diagnosis of prodromal DLB is of limited use in the clinic. That said, knowledge of the prodromal development of DLB could help clinicians identify cases of DLB where the diagnosis is uncertain. Prodromal diagnosis is of great importance in research, where identifying Lewy body disease at an earlier stage may allow researchers to investigate the initial phases of dementia pathophysiology, develop treatments designed to interrupt the development of the dementia syndrome and accurately identify the patients most likely to benefit from these treatments.

Dopamine transporter imaging as a diagnostic tool for parkinsonism and related disorders in clinical practice

Parkinsonism Relat Disord. 2014 Nov 20. pii: S1353-8020(14)00420-9. doi: 10.1016/j.parkreldis.2014.11.007. [Epub ahead of print]

Ba F, Martin WR.

BACKGROUND:

Accurate diagnosis of Parkinson disease (PD) and other degenerative parkinsonian syndromes is important for management and prognostic purposes. Diagnosis can be challenging in early disease and in atypical cases.

METHODS:

We reviewed the literature on the application of dopamine transporter single-photon emission computed tomography (DAT-SPECT) in degenerative parkinsonism and related disorders as a diagnostic tool.

RESULTS:

The use of DAT-SPECT shows some utility in the early diagnosis of PD and differentiation from other non-degenerative parkinsonian disorders (i.e. essential tremor, dystonic tremor, drug-induced and in most cases of psychogenic parkinsonism), since it can accurately detect the presynaptic dopaminergic deficit. The test has been shown to have high sensitivity/specificity by multiple studies. DAT imaging may also have some prognostic value for disease progression. However, it has limited value in differentiating among degenerative causes of parkinsonism. DAT imaging has some limitations. In most studies, true test accuracy is unknown since the gold standard is clinical diagnosis by a movement disorders neurologist. Therefore, the sensitivity of the test cannot exceed that of the clinical diagnosis. In addition, false negative scans occur and highlight the need for clinical follow-up.

CONCLUSION:

Clinical assessment remains the most important aspect in evaluating these patients. DAT-SPECT is a sensitive modality to detect nigrostriatal degeneration. In spite of increasing data using this technique, however, more long-term clinical studies are required to determine how DAT-SPECT scan can guide decision-making.

Four pioneers of L-dopa treatment: Arvid Carlsson, Oleh Hornykiewicz, George Cotzias, and Melvin Yahr

Great to learn more about the people behind what remains our best drug...

http://onlinelibrary.wiley.com/doi/10.1002/mds.26120/abstract;jsessionid=4835F40C74239C25864D71A093321415.f03t03

Mov Disord. 2014 Dec 8. doi: 10.1002/mds.26120. [Epub ahead of print]

Lees AJ, Tolosa E, Olanow CW.

Abstract

Four individuals stand out as pioneers of the early work that led to levodopa becoming a revolutionary new treatment for Parkinson's disease: Arvid Carlsson, Oleh Hornykiewicz, George C. Cotzias, and Melvin D. Yahr. All four were MDs. The first three had extra training in pharmacology, and in fact did their research in pharmacology. The fourth was a clinical neurologist, the only one in this group with those credentials. The story starts with Carlsson, who became interested in studying the mechanism of reserpine's sedative effect, now recognized as a drug-induced parkinsonian state. A key experiment in 1957 showed that levodopa (l-dopa) could alleviate the immobility induced by reserpine in animals. Carlsson then showed that reserpine depleted brain dopamine, and that l-dopa restored it. Carlsson developed a sensitive fluorescent technique to measure dopamine levels, and his laboratory also showed the distribution of dopamine in animal brain to be highest in the striatum. Within a year, Carlsson postulated that dopamine appears to play a role in motor function. His proposal that dopamine serves as a neurotransmitter in brain was met with much skepticism, but he persisted and continued to study brain dopamine, eventually leading to being awarded the Nobel Prize in Medicine in 2000. Hornykiewicz also went into pharmacology research after graduating from medical school. Fortuitously, his assigned first project was on the blood pressure effects of dopamine, recognized as a precursor of norepinephrine. When he completed his postdoctoral studies, Carlsson's work on the reserpinized animal and on the regional distribution of brain dopamine was published. This inspired Hornykiewicz to determine dopamine levels in patients with Parkinson's disease. He obtained postmortem material, and his 1960 paper showed a marked depletion of dopamine in the striatum in this disorder. He went on in subsequent papers to correlate severity of parkinsonian features with the amount of striatal dopamine depletion. In the meantime, after his discovery of low dopamine in brains of patients with Parkinson's disease, Hornykiewicz persuaded Walther Birkmayer to inject l-dopa into patients. They reported success and continued this treatment, usually combining it with the use of a monoamine oxidase inhibitor. However, the response was limited in duration, and subsequent trials by others were not achieving similar success, and many failed to find any benefit. The fulfilment of the l-dopa story stemmed from the hypothesis held by Cotzias that Parkinson's disease was caused by loss of brain neuromelanin in the substantia nigra. Although Cotzias's research had been in pharmacology, he also headed a clinical pharmacology research group at a federal laboratory on Long Island, New York, USA. He decided to try to restore this pigment in patients, not animals, and one of the three drugs he tried was d,l-dopa. As reported in his 1967 article, d,l-dopa proved to be dramatically successful in reversing the symptoms, but at extremely high dosages and with considerable hematologic adverse effects. Cotzias immediately tested l-dopa and found the same benefit with half the dosage and without the hematologic problems. Yahr was a clinical neurologist who had been treating patients with PD with available therapy and also headed a federally financed research group investigating the disorder. Always on the lookout for potential new treatments, he was initially skeptical about l-dopa when studies with low doses were being reported. Seeing videos of patients presented by Cotzias, however, he realized that the results needed confirmation through a double-blind controlled clinical trial. He proceeded to develop and execute such a trial with l-dopa, duplicating Cotzias's success. Both Cotzias and Yahr had encountered motor fluctuations and dyskinesias, but the amelioration of bradykinesia, rigidity, and tremor was so pronounced that these adverse effects did not prevent regulatory approval of l-dopa, and almost 50 years later l-dopa remains the most effective pharmacologic agent for treating Parkinson's disease. This article relates the personal stories of these four pioneers and how they achieved their success.

Identification of candidate genes for Parkinson's disease through blood transcriptome analysis in LRRK2-G2019S carriers, idiopathic cases, and controls

Neurobiol Aging. 2014 Nov 5. pii: S0197-4580(14)00705-2. doi: 10.1016/j.neurobiolaging.2014.10.039. [Epub ahead of print]

Infante J, Prieto C, Sierra M, Sánchez-Juan P, González-Aramburu I, Sánchez-Quintana C, Berciano J, Combarros O, Sainz J.

The commonest known cause of Parkinson's disease (PD) is the G2019S mutation of the LRRK2 gene, but this mutation is not sufficient for causing PD, and many carriers of the mutation never develop PD symptoms during life. Differences at the expression level of certain genes, resulting from either genetic variations or environmental interactions, might be one of the mechanisms underlying differential risks for developing both idiopathic and genetic PD. To identify the genes involved in PD pathogenesis, we compared genome-wide gene expression (RNA-seq) in peripheral blood of 20 PD patients carrying the G2019S mutation of the LRRK2 gene, 20 asymptomatic carriers of the mutation, 20 subjects with idiopathic PD, 20 controls and 7 PD patients before and after initiating dopaminergic therapy. We identified 13 common genes (ADARB2, CEACAM6, CNTNAP2, COL19A1, DEF4, DRAXIN, FCER2, HBG1, NCAPG2, PVRL2, SLC2A14, SNCA, and TCL1B) showing significant differential expression between G2019S-associated PD and asymptomatic carriers and also between idiopathic PD and controls but not between untreated and treated patients. Some of these genes are functionally involved in the processes known to be involved in PD pathogenesis, such as Akt signaling, glucose metabolism, or immunity. We consider that these genes merit further attention in future studies as potential candidate genes involved in both idiopathic and LRRK2-G2019S-associated forms of PD.

The Onset of Nonmotor Symptoms in Parkinson's disease (The ONSET PD Study).

Nice work!!!

Mov Disord. 2014 Dec 1. doi: 10.1002/mds.26077. [Epub ahead of print]

Pont-Sunyer C, Hotter A, Gaig C, Seppi K, Compta Y, Katzenschlager R, Mas N, Hofeneder D, Brücke T, Bayés A, Wenzel K, Infante J, Zach H, Pirker W, Posada IJ, Alvarez R, Ispierto L, De Fàbregues O, Callén A, Palasí A, Aguilar M, Martí MJ, Valldeoriola F, Salamero M, Poewe W, Tolosa E.

Abstract

Nonmotor symptoms (NMS) in Parkinson's disease (PD) can precede onset of motor symptoms. Relationship between premotor symptoms onset and motor features is limited. Our aim is to describe the presence and perceived onset of NMS in PD as well as their possible association with motor phenotype. Presence and onset of NMS were assessed by a custom-made questionnaire in 109 newly diagnosed untreated PD patients and 107 controls from 11 Spanish and Austrian centers. Seventeen of thirty-one NMS were more common in patients than controls (P < 0.05). They were usually mild and frequently reported to occur at different time-spans before motor symptoms. Anhedonia, apathy, memory complaints, and inattention occurred more frequently during the 2-year premotor period. Those reported more frequently in the 2- to 10-year premotor period were smell loss, mood disturbances, taste loss, excessive sweating, fatigue, and pain. Constipation, dream-enacting behavior, excessive daytime sleepiness, and postprandial fullness were frequently perceived more than 10 years before motor symptoms. No correlation between NMS burden and motor severity, age, or gender was observed. NMS associated in four clusters: rapid eye movement sleep behavior disorder symptoms-constipation, cognition-related, mood-related, and sensory clusters. No cluster was associated with a specific motor phenotype or severity. NMS are common in early unmedicated PD and frequently reported to occur in the premotor period. They are generally mild, but a patient subgroup showed high NMS burden mainly resulting from cognition-related symptoms. Certain NMS when present at the time of assessment or in the premotor stage, either alone or in combination, allowed discriminating PD from controls. 

Gut microbiota are related to Parkinson's disease and clinical phenotype

A different and interesting take on the gut and Parkinson's...

Mov Disord. 2014 Dec 5. doi: 10.1002/mds.26069. [Epub ahead of print]

Scheperjans F, Aho V, Pereira PA, Koskinen K, Paulin L, Pekkonen E, Haapaniemi E, Kaakkola S, Eerola-Rautio J, Pohja M, Kinnunen E, Murros K, Auvinen P.

Abstract

In the course of Parkinson's disease (PD), the enteric nervous system (ENS) and parasympathetic nerves are amongst the structures earliest and most frequently affected by alpha-synuclein pathology. Accordingly, gastrointestinal dysfunction, in particular constipation, is an important non-motor symptom in PD and often precedes the onset of motor symptoms by years. Recent research has shown that intestinal microbiota interact with the autonomic and central nervous system via diverse pathways including the ENS and vagal nerve. The gut microbiome in PD has not been previously investigated. We compared the fecal microbiomes of 72 PD patients and 72 control subjects by pyrosequencing the V1-V3 regions of the bacterial 16S ribosomal RNA gene. Associations between clinical parameters and microbiota were analyzed using generalized linear models, taking into account potential confounders. On average, the abundance of Prevotellaceae in feces of PD patients was reduced by 77.6% as compared with controls. Relative abundance of Prevotellaceae of 6.5% or less had 86.1% sensitivity and 38.9% specificity for PD. A logistic regression classifier based on the abundance of four bacterial families and the severity of constipation identified PD patients with 66.7% sensitivity and 90.3% specificity. The relative abundance of Enterobacteriaceae was positively associated with the severity of postural instability and gait difficulty. These findings suggest that the intestinal microbiome is altered in PD and is related to motor phenotype. Further studies are warranted to elucidate the temporal and causal relationships between gut microbiota and PD and the suitability of the microbiome as a biomarker.

Inflammation is genetically implicated in Parkinson's disease

Neuroscience. 2014 Oct 22. pii: S0306-4522(14)00892-6. doi: 10.1016/j.neuroscience.2014.10.028. [Epub ahead of print]

Dzamko N, Geczy CL, Halliday GM.

http://www.sciencedirect.com/science/article/pii/S0306452214008926

Abstract

Inflammation has long been associated with the pathogenesis of Parkinson's disease (PD) but the extent to which it is a cause or consequence is sill debated. Over the past decade a number of genes have been implicated in PD. Relatively rare missense mutations in genes such as LRRK2, Parkin, SNCA and PINK1 are causative for familial PD whereas more common variation in genes, including LRRK2, SNCA and GBA, comprise risk factors for sporadic PD. Determining how the function of these genes and the proteins they encode are altered in PD has become a priority, as results will likely provide much needed insights into contributing causes. Accumulating evidence indicates that many of these genes function in pathways that regulate aspects of immunity, particularly inflammation, suggesting close associations between PD and immune homeostasis.

Clinical characteristics related to worsening of motor function assessed by the Unified Parkinson's Disease Rating Scale in the elderly population

J Neurol. 2014 Dec 2. [Epub ahead of print]

Liepelt-Scarfone I, Lerche S, Behnke S, Godau J, Gaenslen A, Pausch C, Fassbender K, Brockmann K, Srulijes K, Huber H, Wurster I, Berg D.

http://link.springer.com/article/10.1007%2Fs00415-014-7584-4

Abstract

There is evidence that nigrostriatal pathology may at least partly underlie mild Parkinsonian signs. We evaluated whether an increase in the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) could be predicted by the presence of risk and prodromal markers for neurodegenerative diseases in elderly individuals without those diseases. Therefore, we analyzed the UPDRS-III score and various risk and prodromal markers known to antecede neurodegenerative diseases in a population-based cohort comprising 807 individuals free of neurodegenerative diseases at baseline. After 5 years, eight persons (1.0 %) were diagnosed with Parkinson's Disease (PD). Of those, seven (87.5 %) had motor worsening ≥3 points on the UPDRS-III from baseline to follow-up, one had two points increase. Of the 788 people without PD, 568 (72.1 %) showed no increase in the UPDRS-III scale, 220 (27.9 %) had ≥1 point increase and out of these 104 (13.2 %) had an increase of ≥3 points in the UPDRS-III score after 5 years. We identified an age >60 years (relative risk, RR = 1.7; confidence interval, CI 1.3-2.1) and the occurrence of ≥2 risk factors (RR = 1.5; CI 1.2-1.9) as possible predictors of motor progression. After 5 years, individuals with an increase in the UPDRS-III score had more often a one-sided reduced arm swing (p < 0.001) and identified less odors in the Sniffin' sticks test (p < 0.041) than persons with stable motor performance. Our data support the assumption that progression of Parkinsonian signs assessed by the UPDRS-III parallels the development of prodromal markers for neurodegenerative diseases in the elderly population.

REM sleep behaviour disorder: How useful is it for the differential diagnosis of parkinsonism?

Clin Neurol Neurosurg. 2014 Dec;127:71-4. doi: 10.1016/j.clineuro.2014.09.014. Epub 2014 Oct 5.

Munhoz RP, Teive HA.

http://www.clineu-journal.com/article/S0303-8467(14)00376-X/abstract

BACKGROUND:

REM sleep behaviour disorder (RBD) is typically linked to synucleinopathies (SP). In this study we analyzed the utility and performance of RBD as a tool for the differential diagnosis of the most common forms of degenerative parkinsonism, including SPs and tauopathies.

METHODS:

Patients with a syndromic diagnosis of degenerative parkinsonism matched for gender, age, and disease stage were assessed using a structured protocol with demographic and clinical data, including the diagnosis of probable RBD (pRBD), ascertained clinically using established criteria.

RESULTS:

One hundred cases of Parkinson's disease (PD), 87 with progressive supranuclear palsy (PSP), 72 with the parkinsonian form of multiple system atrophy (MSA), 50 with dementia with Lewy bodies (DLB), and 18 with corticobasal degeneration (CBD) were included. pRBD was found in 58 (58%) of the PD patients, 59 (81.9%) of those with MSA, 37 (74%) with DLB, 32 (36.7%) with PSP, and one (5.5%) with CBD. Among the SPs, pRBD was significantly more common in MSA when compared with PD patients. Differences were also significant individually for all SPs when compared to PSP. The positive predictive value (PPV) of pRBD for a SP was 82.3%, but sensitivity was 69.4% and specificity 68.6%.

CONCLUSIONS:

In our sample, pRBD was more frequent in SPs than in PSP and CBD, however, its' frequency in PSP was significant. Although pRBD had a good PPV for a SP, all other measurements used for determine diagnostic performance were disappointing.

The ongoing pursuit of neuroprotective therapies in Parkinson disease.

And of course if the aim in to detect at-risk or prodromal PD, then this goes hand-in-hand...

http://www.nature.com/nrneurol/journal/vaop/ncurrent/full/nrneurol.2014.226.html

Nat Rev Neurol. 2014 Dec 2. doi: 10.1038/nrneurol.2014.226. [Epub ahead of print]

Athauda D, Foltynie T.

Abstract

Many agents developed for neuroprotective treatment of Parkinson disease (PD) have shown great promise in the laboratory, but none have translated to positive results in patients with PD. Potential neuroprotective drugs, such as ubiquinone, creatine and PYM50028, have failed to show any clinical benefits in recent high-profile clinical trials. This 'failure to translate' is likely to be related primarily to our incomplete understanding of the pathogenic mechanisms underlying PD, and excessive reliance on data from toxin-based animal models to judge which agents should be selected for clinical trials. Restricted resources inevitably mean that difficult compromises must be made in terms of trial design, and reliable estimation of efficacy is further hampered by the absence of validated biomarkers of disease progression. Drug development in PD dementia has been mostly unsuccessful; however, emerging biochemical, genetic and pathological evidence suggests a link between tau and amyloid-β deposition and cognitive decline in PD, potentially opening up new possibilities for therapeutic intervention. This Review discusses the most important 'druggable' disease mechanisms in PD, as well as the most-promising drugs that are being evaluated for their potential efficiency in treatment of motor and cognitive impairments in PD.