STN vs. GPi Deep Brain Stimulation: Translating the Rematch into Clinical Practice

Mov Disord Clin Pract (Hoboken). 2014 Apr 1;1(1):24-35.

Williams NR, Foote KD, Okun MS.

Abstract

When formulating a deep brain stimulation (DBS) treatment plan for a patient with Parkinson's disease (PD), two critical questions should be addressed: 1- Which brain target should be chosen to optimize this patient's outcome? and 2- Should this patient's DBS operation be unilateral or bilateral? Over the past two decades, two targets have emerged as leading contenders for PD DBS; the subthalamic nucleus (STN) and the globus pallidus internus (GPi). While the GPi target does have a following, most centers have uniformly employed bilateral STN DBS for all Parkinson's disease cases (Figure 1). This bilateral STN "one-size-fits-all" approach was challenged by an editorial entitled "STN vs. GPi: The Rematch," which appeared in the Archives of Neurology in 2005. Since 2005, a series of well designed clinical trials and follow-up studies have addressed the question as to whether a more tailored approach to DBS therapy might improve overall outcomes. Such a tailored approach would include the options of targeting the GPi, or choosing a unilateral operation. The results of the STN vs. GPi 'rematch' studies support the conclusion that bilateral STN DBS may not be the best option for every Parkinson's disease surgical patient. Off period motor symptoms and tremor improve in both targets, and with either unilateral or bilateral stimulation. Advantages of the STN target include more medication reduction, less frequent battery changes, and a more favorable economic profile. Advantages of GPi include more robust dyskinesia suppression, easier programming, and greater flexibility in adjusting medications. In cases where unilateral stimulation is anticipated, the data favor GPi DBS. This review summarizes the accumulated evidence regarding the use of bilateral vs. unilateral DBS and the selection of STN vs. GPi DBS, including definite and possible advantages of different targets and approaches. Based on this evidence, a more patient-tailored, symptom specific approach will be proposed to optimize outcomes of PD DBS therapy. Finally, the importance of an interdisciplinary care team for screening and effective management of DBS patients will be reaffirmed. Interdisciplinary teams can facilitate the proposed patient-specific DBS treatment planning and provide a more thorough analysis of the risk-benefit ratio for each patient.

Accurate Detection of Parkinson's Disease in Tremor Syndromes Using Olfactory Testing

Be careful not to sniff too hard with stick number 16!

Eur Neurol. 2014 Apr 26;72(1-2):1-6. [Epub ahead of print]

Wolz M, Hähner A, Meixner L, Löhle M, Reichmann H, Hummel T, Storch A.

Abstract

Background/Aims: The diagnostic value of olfactory testing for the discrimination of tremor-dominant Parkinson's disease (PD) from other tremor disorders remains enigmatic. We evaluated whether olfactory testing can accurately detect PD in tremor patients. Methods: A retrospective analysis of 299 consecutive subjects referred for the differential diagnosis of a tremor disorder was done. Olfactory testing was performed using 'Sniffin' Sticks', resulting in a composite TDI score of odor threshold (T), discrimination (D), and identification (I). Receiver operating curve (ROC) plots were used to calculate sensitivity/specificity for the detection of PD. Results: Of all subjects, 167 (55.9%) had PD and 85 (28.4%) had essential tremor (ET). The mean TDI score in PD was significantly reduced compared to those in ET and other tremor disorders with no differences between ET and other tremor disorders. ROC analysis revealed strong correlations of TDI scores with PD [area under the curve: 0.85 (95% CI: 0.80-0.89); p < 0.001]. The highest Youden index was observed for a TDI score <25 (Youden index: 0.58). Using this cutoff score and that generated from normative data of healthy controls, the TDI score provided high sensitivity (negative predictive value) and specificity (positive predictive value) of approximately 80% for detecting PD. Conclusion: Olfactory testing is a useful, easily applied and inexpensive diagnostic test which is helpful to detect PD among tremor patients.

Reproductive factors and Parkinson's disease risk in Danish women

Our previous meta-analysis did not suggest these female factors were associated with Parkinson's

Eur J Neurol. 2014 Apr 22. doi: 10.1111/ene.12450. [Epub ahead of print]

Greene N, Lassen CF, Rugbjerg K, Ritz B.

Abstract

BACKGROUND AND PURPOSE:

Parkinson's disease is more common in men than women by a ratio of about 1.5:1 and yet there is no consensus to date as to whether female reproductive factors including hormone use affect Parkinson's disease risk. Our objective was to examine the relationship between Parkinson's disease and female reproductive factors in the largest population-based Parkinson's disease case-control study to date.

METHODS:

Seven hundred and forty-three female Parkinson's disease cases diagnosed between 1996 and 2009 were selected from the Danish National Hospital Register, diagnoses confirmed by medical record review, and the cases were matched by birth year to 765 female controls randomly selected from the Danish Civil Registration System. Covariate information was collected in computer-assisted telephone interviews covering an extensive array of topics including reproductive and lifestyle factors.

RESULTS:

After adjusting for smoking, caffeine and alcohol use, education, age, and family Parkinson's disease history, inverse associations between Parkinson's disease and early menarche (first period at ≤11 years), oral contraceptives, high parity (≥4 children) and bilateral oophorectomy were found; adjusted odds ratios and 95% confidence limits were respectively 0.68 (0.45-1.03) for early menarche, 0.87 (0.69-1.10) for oral contraceptives, 0.79 (0.59-1.06) for high parity and 0.65 (0.45-0.94) for bilateral oophorectomy. Little support for associations between Parkinson's disease and fertile life length, age at menopause or post-menopausal hormone treatment was found.

CONCLUSIONS:

Reproductive factors related to women's early- to mid-reproductive lives appear to be predictive of subsequent Parkinson's disease risk whereas factors occurring later in life seem less important.

CSF Aβ42 predicts early-onset dementia in Parkinson disease.

Neurology. 2014 Apr 18. [Epub ahead of print]

Alves G, Lange J, Blennow K, Zetterberg H, Andreasson U, Førland MG, Tysnes OB, Larsen JP, Pedersen KF.

Abstract

OBJECTIVE:

To test in vivo the proposal from clinicopathologic studies that β-amyloid (Aβ) pathology shortens the time to dementia in Parkinson disease (PD), and to explore the utility of CSF Aβ and related measures as early prognostic biomarkers of dementia in an incident PD cohort.

METHODS:

We assessed a population-based incident cohort of 104 patients with PD who underwent lumbar puncture at diagnosis. We analyzed CSF concentrations of Aβ42, Aβ40, and Aβ38 using a multiplexed immunoassay with electrochemiluminescence (ECL) detection and levels of Aβ42, total tau, and phosphorylated tau using ELISA. Patients were followed prospectively for 5 years. Dementia was diagnosed according to published criteria.

RESULTS:

CSF levels of Aβ42 were significantly decreased in patients who developed dementia (n = 20, 19.2%) compared to those who did not (n = 84, 80.8%), as measured by ECL (-33%, p = 0.006) as well as ELISA (-36%, p < 0.001). No differences were observed for other markers. Low Aβ42 values predicted a substantially increased risk for subsequent dementia at high sensitivity (≥85%), with hazard ratios of 9.9 (95% confidence interval 2.3-43.5, p = 0.002) for Aβ42ECL <376 pg/mL and 7.6 (2.2-26.4, p = 0.001) for Aβ42ELISA <443 pg/mL, after adjustment for baseline age and PD-mild cognitive impairment (MCI) status. Aβ42 reductions tended to precede the onset of PD-MCI that progressed to dementia.

CONCLUSIONS:

These in vivo data support the role of Aβ pathology in the etiology and highlight the potential utility of CSF Aβ42 as an early prognostic biomarker of dementia associated with PD.

Insights from the Global Longitudinal Study of Osteoporosis in Women (GLOW).

The GLOW study has informed a lot of our recent work on fracture risk in Parkinson's

Nat Rev Endocrinol. 2014 Apr 22. doi: 10.1038/nrendo.2014.55. [Epub ahead of print]

Watts NB.

Abstract

GLOW is an observational, longitudinal, practice-based cohort study of osteoporosis in 60,393 women aged ≥55 years in 10 countries on three continents. In this Review, we present insights from the first 3 years of the study. Despite cost analyses being frequently based on spine and hip fractures, we found that nonvertebral, nonhip fractures were around five times more common and doubled the use of health-care resources compared with hip and spine fractures combined. Fractures not at the four so-called major sites in FRAX® (upper arm, forearm, hip and clinical vertebral fractures) account for >40% of all fractures. The risk of fracture is increased by various comorbidities, such as Parkinson disease, multiple sclerosis and lung and heart disease. Obesity, although thought to be protective against all fractures, substantially increased the risk of fractures in the ankle or lower leg. Simple assessment by age plus fracture history has good predictive value for all fractures, but risk profiles differ for first and subsequent fractures. Fractures diminish quality of life as much or more than diabetes mellitus, arthritis and lung disease, yet women substantially underestimate their own fracture risk. Treatment rates in patients at high risk of fracture are below those recommended but might be too frequent in women at low risk. Comorbidities and the limits of current therapeutic regimens jeopardize the efficacy of drugs; new regimens should be explored for severe cases.

Gut feelings about smoking and coffee in Parkinson's disease.

Mov Disord. 2014 Apr 21. doi: 10.1002/mds.25882. [Epub ahead of print]

Derkinderen P, Shannon KM, Brundin P.

Abstract

Strong epidemiologic evidence suggests that smokers and coffee drinkers have a lower risk of Parkinson's disease (PD). The explanation for this finding is still unknown, and the discussion has focused on two main hypotheses. The first suggests that PD patients have premorbid personality traits associated with dislike for coffee-drinking and smoking. The second posits that caffeine and nicotine are neuroprotective. We propose an alternative third hypothesis, in which both cigarette and coffee consumption change the composition of the microbiota in the gut in a way that mitigates intestinal inflammation. This, in turn, would lead to less misfolding of the protein alpha-synuclein in enteric nerves, reducing the risk of PD by minimizing propagation of the protein aggregates to the central nervous system, where they otherwise can induce neurodegeneration. 

Comparison of Parkinson Risk in Ashkenazi Jewish Patients With Gaucher Disease and GBA Heterozygotes

Roy N. Alcalay; Tama Dinur; Timothy Quinn; Karina Sakanaka; Oren Levy; Cheryl Waters; Stanley Fahn; Tsvyatko Dorovski; Wendy K. Chung, MD; Michael Pauciulo; William Nichols; Huma Q. Rana; Manisha Balwani; Louise Bier; Deborah Elstein; Ari Zimran

JAMA Neurol. Published online April 21, 2014. doi:10.1001/jamaneurol.2014.313

Importance  Information on age-specific risk for Parkinson disease (PD) in patients with Gaucher disease (GD) and glucocerebrosidase (GBA) heterozygotes is important for understanding the pathophysiology of the genetic association and for counseling these populations.

Objective  To estimate the age-specific risk for PD in Ashkenazi Jewish patients with type 1 GD and in GBA heterozygotes.

Design, Setting, and Participants  The study included patients with GD from 2 tertiary centers, Shaare Zedek Medical Center, Jerusalem, Israel (n = 332) and Mount Sinai School of Medicine, New York, New York (n = 95). GBA noncarrier non-PD spouse control participants were recruited at the Center for Parkinson’s Disease at Columbia University, New York (n = 77). All participants were Ashekanzi Jewish and most patients (98.1%) with GD carried at least 1 N370S mutation.

Main Outcomes and Measures  The main outcome measure was a diagnosis of PD. Diagnosis was established in patients with GD on examination. We used a validated family history interview that identifies PD with a sensitivity of 95.5% and specificity of 96.2% to identify PD in family members. Kaplan-Meier survival curves were used to estimate age-specific PD risk among patients with GD (n = 427), among their parents who are obligate GBA mutation carriers (heterozygotes, n = 694), and among noncarriers (parents of non-PD, non-GD control participants, n = 154). The age-specific risk was compared among groups using the log-rank test.

Results  Among those who developed PD, patients with GD had a younger age at onset than GBA heterozygotes (mean, 54.2 vs 65.2 years, respectively; P = .003). Estimated age-specific risk for PD at 60 and 80 years of age was 4.7% and 9.1% among patients with GD, 1.5% and 7.7% among heterozygotes, and 0.7% and 2.1% among noncarriers, respectively. The risk for PD was higher in patients with GD than noncarriers (P = .008, log-rank test) and in heterozygotes than noncarriers (P = .03, log-rank test), but it did not reach statistical significance between patients with GD and GBA heterozygotes (P = .07, log-rank test).

Conclusions and Relevance  Patients with GD and GBA heterozygotes have an increased age-specific risk for PD compared with control individuals, with a similar magnitude of PD risk by 80 years of age; however, the number of mutant alleles may play an important role in age at PD onset.

Memantine improves attention and episodic memory in Parkinson's disease dementia and dementia with Lewy bodies

Int J Geriatr Psychiatry. 2014 Apr 16. doi: 10.1002/gps.4109. [Epub ahead of print]

Wesnes KA, Aarsland D, Ballard C, Londos E.

Abstract

OBJECTIVE:

In both dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), attentional dysfunction is a core clinical feature together with disrupted episodic memory. This study evaluated the cognitive effects of memantine in DLB and PDD using automated tests of attention and episodic memory.

METHODS:

A randomised double-blind, placebo-controlled, 24-week three centre trial of memantine (20 mg/day) was conducted in which tests of attention (simple and choice reaction time) and word recognition (immediate and delayed) from the CDR System were administered prior to dosing and again at 12 and 24 weeks. Although other results from this study have been published, the data from the CDR System tests were not included and are presented here for the first time.

RESULTS:

Data were available for 51 patients (21 DLB and 30 PDD). In both populations, memantine produced statistically significant medium to large effect sized improvements to choice reaction time, immediate and delayed word recognition.

CONCLUSIONS:

These are the first substantial improvements on cognitive tests of attention and episodic recognition memory identified with memantine in either DLB or PDD.

Uncovering the role of the insula in non-motor symptoms of Parkinson's disease

Brain. 2014 Apr 15. [Epub ahead of print]

Christopher L, Koshimori Y, Lang AE, Criaud M, Strafella AP.

Abstract

Patients with Parkinson's disease experience a range of non-motor symptoms, including cognitive impairment, behavioural changes, somatosensory and autonomic disturbances. The insula, which was once thought to be primarily a limbic cortical structure, is now known to be highly involved in integrating somatosensory, autonomic and cognitive-affective information to guide behaviour. Thus, it acts as a central hub for processing relevant information related to the state of the body as well as cognitive and mood states. Despite these crucial functions, the insula has been largely overlooked as a potential key region in contributing to non-motor symptoms of Parkinson's disease. The insula is affected in Parkinson's disease by alpha-synuclein deposition, disruptions in normal neurotransmitter function, alterations in connectivity as well as metabolic and structural changes. Although research focusing on the role of the insula in Parkinson's disease is scarce, there is evidence from neuroimaging studies linking the insula to cognitive decline, behavioural abnormalities and somatosensory disturbances. Here, we review imaging studies that provide insight into the potential role of the insula in Parkinson's disease non-motor symptoms.

Efficacy of occupational therapy for patients with Parkinson's disease: a randomised controlled trial

Further support that the 'therapies' are as valuable as the 'therapeutics' in PD. A tailored and multi-faceted approach can bring many benefits to patients. Whilst we've heard a lot about the benefits of physiotherapy and speech & language therapy in recent years, we have not heard so much about occupational therapy. However from day-to-day clinical experience we know their input is vital!

Lancet Neurol. 2014 Apr 8. pii: S1474-4422(14)70055-9. doi: 10.1016/S1474-4422(14)70055-9. [Epub ahead of print]

Sturkenboom IH, Graff MJ, Hendriks JC, Veenhuizen Y, Munneke M, Bloem BR, der Sanden MW; for the OTiP study group.

Abstract

BACKGROUND:

There is insufficient evidence to support use of occupational therapy interventions for patients with Parkinson's disease. We aimed to assess the efficacy of occupational therapy in improving daily activities of patients with Parkinson's disease.

METHODS:

We did a multicentre, assessor-masked, randomised controlled clinical trial in ten hospitals in nine Dutch regional networks of specialised health-care professionals (ParkinsonNet), with assessment at 3 months and 6 months. Patients with Parkinson's disease with self-reported difficulties in daily activities were included, along with their primary caregivers. Patients were randomly assigned (2:1) to the intervention or control group by a computer-generated minimisation algorithm. The intervention consisted of 10 weeks of home-based occupational therapy according to national practice guidelines; control individuals received usual care with no occupational therapy. The primary outcome was self-perceived performance in daily activities at 3 months, assessed with the Canadian Occupational Performance Measure (score 1-10). Data were analysed using linear mixed models for repeated measures (intention-to-treat principle). Assessors monitored safety by asking patients about any unusual health events during the preceding 3 months. This trial is registered with ClinicalTrials.gov, NCT01336127.

FINDINGS:

Between April 14, 2011, and Nov 2, 2012, 191 patients were randomly assigned to the intervention group (n=124) or the control group (n=67). 117 (94%) of 124 patients in the intervention group and 63 (94%) of 67 in the control group had a participating caregiver. At baseline, the median score on the Canadian Occupational Performance Measure was 4·3 (IQR 3·5-5·0) in the intervention group and 4·4 (3·8-5·0) in the control group. At 3 months, these scores were 5·8 (5·0-6·4) and 4·6 (4·6-6·6), respectively. The adjusted mean difference in score from baseline between groups at 3 months was in favour of the intervention group (1·2; 95% CI 0·8-1·6; p<0·0001). There were no adverse events associated with the study.

INTERPRETATION:

Home-based, individualised occupational therapy led to an improvement in self-perceived performance in daily activities in patients with Parkinson's disease. Further work should identify which factors related to the patient, environmental context, or therapist might predict which patients are most likely to benefit from occupational therapy.

FUNDING:

Prinses Beatrix Spierfonds and Parkinson Vereniging.

Cerebrospinal fluid biomarkers in parkinsonian conditions: an update and future directions

Common sense tells you that if a strong biomarker for PD is to be found, it ought to be in the CSF.

J Neurol Neurosurg Psychiatry. 2014 Apr 1. doi: 10.1136/jnnp-2013-307539. [Epub ahead of print]

Magdalinou N, Lees AJ, Zetterberg H.

Abstract

Parkinsonian diseases comprise a heterogeneous group of neurodegenerative disorders, which show significant clinical and pathological overlap. Accurate diagnosis still largely relies on clinical acumen; pathological diagnosis remains the gold standard. There is an urgent need for biomarkers to diagnose parkinsonian disorders, particularly in the early stages when diagnosis is most difficult. In this review, several of the most promising cerebrospinal fluid candidate markers will be discussed. Their strengths and limitations will be considered together with future developments in the field.

Evaluation of mild cognitive impairment subtypes in Parkinson's disease

Mov Disord. 2014 Apr 7. doi: 10.1002/mds.25875. [Epub ahead of print]

Cholerton BA, Zabetian CP, Wan JY, Montine TJ, Quinn JF, Mata IF, Chung KA, Peterson A, Espay AJ, Revilla FJ, Devoto J, Watson GS, Hu SC, Leverenz JB, Edwards KL.

Abstract

Mild cognitive impairment in Parkinson's disease (PD-MCI) is common and increases the risk for dementia. Establishing distinct PD-MCI cognitive subtypes could be valuable for eventually predicting those most likely to convert to dementia. However, the study of PD-MCI subtypes has not yielded consistent results among cohorts. To determine whether there are distinct cognitive subtypes among participants diagnosed with PD-MCI in the Pacific Northwest Udall Center Clinical Consortium, we cognitively subtyped 95 patients with PD-MCI, using the Movement Disorders Society Task Force diagnostic guidelines. Psychometric test scores were then subjected to principle components factor analysis to determine whether similar cognitive subgroups could be identified using statistical methodology. Multiple-domain PD-MCI was diagnosed in 95% of the sample, and a range of cognitive impairments were noted. Factor analysis yielded seven factors and demonstrated overlap of phonemic verbal fluency on two factors, as well as the loading of verbal fluency on the same factor as a visuospatial measure; however, these factors did not partition the sample into distinct cognitive subtypes. Separation of cognitive subtypes based on the current PD-MCI criteria, or via statistical methods, may not provide sufficient information to describe distinct PD groups. Future efforts to validate the PD-MCI criteria and identify combinations of genetic or other risk factors for cognitive impairment are warranted.

Presynaptic dopamine depletion predicts levodopa-induced dyskinesia in de novo Parkinson disease

Neurology. 2014 Apr 9. [Epub ahead of print]

Hong JY, Oh JS, Lee I, Sunwoo MK, Ham JH, Lee JE, Sohn YH, Kim JS, Lee PH.

Abstract

OBJECTIVE:

To investigate whether the magnitude of presynaptic dopamine depletion is a risk factor for the development of levodopa-induced dyskinesia (LID) in Parkinson disease (PD) by quantitatively analyzing 18F-FP-CIT PET data.

METHODS:

This retrospective cohort study enrolled a total of 127 drug-naive de novo patients with PD who completed 18F-FP-CIT PET scanning at their initial evaluation. The patients visited our outpatient clinic every 3-6 months and had been followed for a minimum of 2 years since beginning dopaminergic medication. The predictive power of the quantitatively analyzed 18F-FP-CIT uptake of striatal subregions and other clinical factors for the development of LID was evaluated using Cox proportional hazard models.

RESULTS:

During a mean follow-up period of 3.4 years, 35 patients with PD (27.6%) developed LID. Patients with LID showed less dopamine transporter (DAT) activity in the putamen than did those without LID. Multivariate Cox proportional hazard models revealed that the DAT uptakes of the anterior putamen (hazard ratio [HR] 0.530; p = 0.032), posterior putamen (HR 0.302; p = 0.024), and whole putamen (HR 0.386; p = 0.022) were significant predictors of the development of LID, whereas DAT activities in the caudate and ventral striatum were not significantly correlated with the development of LID. In addition, younger age at onset of PD and higher dose of levodopa were also significant predictors of the development of LID.

CONCLUSIONS:

The present results provide convincing evidence that presynaptic dopaminergic denervation in PD plays a crucial role in the development of LID.

A service development study of the assessment and management of fracture risk in Parkinson's disease

As promised here is the service development study suggesting who and when to screen for fracture risk. Fractures are a major cause of mortality and morbidity in PD. They are preventable!

J Neurol. 2014 Apr 10. [Epub ahead of print]

Shribman S, Torsney KM, Noyce AJ, Giovannoni G, Fearnley J, Dobson R.

Abstract

Parkinson's disease (PD) is associated with an increased risk of fragility fracture. FRAX and Qfracture are risk calculators that estimate the 10-year risk of hip and major fractures and guide definitive investigation for osteoporosis using dual X-ray absorptiometry (DEXA) imaging. It is unclear which PD patients should be considered for fracture risk assessment and whether FRAX or Qfracture should be used. Seventy-seven patients with PD were recruited in the movement disorders clinic. Data were collected on PD-related characteristics and fracture risk scores were calculated. Patients with previous osteoporotic fractures had a higher incidence of falls (p = 0.0026) and use of bilateral walking aids (p = 0.0187) in addition to longer disease duration (p = 0.0037). Selecting patients with falls in combination with either disease duration >5 years, bilateral walking aids, or previous osteoporotic fracture distinguished patients with and without previous osteoporotic fracture with specificity 67.7 % (95 % CI 55.0-78.8) and sensitivity 100.0 % (95 % CI 73.5-100.0). Qfracture calculated significantly higher fracture risk scores than FRAX for hip (p < 0.0001) and major (p = 0.0008) fracture in PD patients. Receiver operating characteristic curves demonstrated that FRAX outperformed Qfracture with an area under the curve of 0.84 (95 % CI 0.70-0.97, p = 0.0004) for FRAX and 0.68 (95 % CI 52-86, p = 0.0476) for Qfracture major fracture risk calculators. We suggest that falls in combination with either a disease duration longer than 5 years or bilateral walking aids or previous osteoporotic fracture should be used as red flags in PD patients to prompt clinicians to perform a FRAX fracture risk assessment in the neurology clinic.

Alpha-synuclein in peripheral tissues and body fluids as a biomarker for Parkinson's disease - a systematic review.

Nice up to date review of the field...

Acta Neurol Scand. 2014 Apr 5. doi: 10.1111/ane.12247. [Epub ahead of print]

Malek N, Swallow D, Grosset KA, Anichtchik O, Spillantini M, Grosset DG.

Abstract

Parkinson's disease (PD) is neuropathologically characterized as an alpha-synucleinopathy. Alpha-synuclein-containing inclusions are stained as Lewy bodies and Lewy neurites in the brain, which are the pathological hallmark of PD. However, alpha-synuclein-containing inclusions in PD are not restricted to the central nervous system, but are also found in peripheral tissues. Alpha-synuclein levels can also be measured in body fluids. The aim of this study was to conduct a systematic review of available evidence to determine the utility of alpha-synuclein as a peripheral biomarker of PD. We searched PubMed (1948 to 26 May 2013), Embase (1974 to 26 May 2013), the Cochrane Library (up to 26 May 2013), LILACS (up to 26 May 2013) and CINAHL (up to 26 May 2013) for the studies of alpha-synuclein in peripheral tissues or body fluids in PD. A total of 49 studies fulfilled the search criteria. Peripheral tissues such as colonic mucosa showed a sensitivity of 42-90% and a specificity of 100%; submandibular salivary glands showed sensitivity and specificity of 100%; skin biopsy showed 19% sensitivity and 80% specificity in detecting alpha-synuclein pathology. CSF alpha-synuclein had 71-94% sensitivity and 25-53% specificity for distinguishing PD from controls. Plasma alpha-synuclein had 48-53% sensitivity and 69-85% specificity. Neither plasma nor CSF alpha-synuclein is presently a reliable marker of PD. This differs from alpha-synuclein in solid tissue samples of the enteric and autonomic nervous system, which offer some potential as a surrogate marker of brain synucleinopathy.

The 'Swallow Tail' Appearance of the Healthy Nigrosome - A New Accurate Test of Parkinson's Disease: A Case-Control and Retrospective Cross-Sectional MRI Study at 3T

PLoS One. 2014 Apr 7;9(4):e93814. doi: 10.1371/journal.pone.0093814. eCollection 2014.

Schwarz ST, Afzal M, Morgan PS, Bajaj N, Gowland PA, Auer DP.

Abstract

There is no well-established in vivo marker of nigral degeneration in Parkinson's disease (PD). An ideal imaging marker would directly mirror the loss of substantia nigra dopaminergic neurones, which is most prominent in sub-regions called nigrosomes. High-resolution, iron-sensitive, magnetic resonance imaging (MRI) at 7T allows direct nigrosome-1 visualisation in healthy people but not in PD. Here, we investigated the feasibility of nigrosome-1 detection using 3T - susceptibility-weighted (SWI) MRI and the diagnostic accuracy that can be achieved for diagnosing PD in a clinical population. 114 high-resolution 3T - SWI-scans were reviewed consisting of a prospective case-control study in 19 subjects (10 PD, 9 controls) and a retrospective cross-sectional study in 95 consecutive patients undergoing routine clinical SWI-scans (>50 years, 9 PD, 81 non-PD, 5 non-diagnostic studies excluded). Two raters independently classified subjects into PD and non-PD according to absence or presence of nigrosome-1, followed by consensus reading. Diagnostic accuracy was assessed against clinical diagnosis as gold standard. Absolute inter- and intra-rater agreement was ≥94% (kappa≥0.82, p<0.001). In the prospective study 8/9 control and 8/10 PD; and in the retrospective study 77/81 non-PD and all 9 PD subjects were correctly classified. Diagnostic accuracy of the retrospective cohort was: sensitivity 100%, specificity 95%, NPV 1, PPV 0.69 and accuracy 96% which dropped to 91% when including non-diagnostic scans ('intent to diagnose'). The healthy nigrosome-1 can be readily depicted on high-resolution 3T - SWI giving rise to a 'swallow tail' appearance of the dorsolateral substantia nigra, and this feature is lost in PD. Visual radiological assessment yielded a high diagnostic accuracy for PD vs. an unselected clinical control population. Assessing the substantia nigra on SWI for the typical 'swallow tail' appearance has potential to become a new and easy applicable 3T MRI diagnostic tool for nigral degeneration in PD.

Ursocholanic acid rescues mitochondrial function in common forms of familial Parkinson's disease

High throughput screening for drug repositioning for PD. This seems like a very good way forward!

Brain. 2013 Oct;136(Pt 10):3038-50. doi: 10.1093/brain/awt224. Epub 2013 Sep 2.
Mortiboys H1, Aasly J, Bandmann O

Abstract

Previous drug screens aiming to identify disease-modifying compounds for Parkinson's disease have typically been based on toxin-induced in vitro and in vivo models of this neurodegenerative condition. All these compounds have failed to have a reliable disease-modifying effect in subsequent clinical trials. We have now established a novel approach, namely to screen an entire compound library directly in patient tissue to identify compounds with a rescue effect on mitochondrial dysfunction as a crucial pathogenic mechanism in Parkinson's disease. The chosen Microsource Compound library contains 2000 compounds, including 1040 licensed drugs and 580 naturally occurring compounds. All 2000 compounds were tested in a step-wise approach for their rescue effect on mitochondrial dysfunction in parkin (PARK2) mutant fibroblasts. Of 2000 compounds, 60 improved the mitochondrial membrane potential by at least two standard deviations. Subsequently, these 60 compounds were assessed for their toxicity and drug-like dose-response. The remaining 49 compounds were tested in a secondary screen for their rescue effect on intracellular ATP levels. Of 49 compounds, 29 normalized ATP levels and displayed drug-like dose response curves. The mitochondrial rescue effect was confirmed for 15 of these 29 compounds in parkin-mutant fibroblasts from additional patients not included in the initial screen. Of 15 compounds, two were chosen for subsequent functional studies, namely ursocholanic acid and the related compound dehydro(11,12)ursolic acid lactone. Both compounds markedly increased the activity of all four complexes of the mitochondrial respiratory chain. The naturally occurring compound ursolic acid and the licensed drug ursodeoxycholic acid are chemically closely related to ursocholanic acid and dehydro(11,12)ursolic acid lactone. All four substances rescue mitochondrial function to a similar extent in parkin-mutant fibroblasts, suggesting a class effect. The mitochondrial rescue effect depends on activation of the glucocorticoid receptor with increased phosphorylation of Akt and was confirmed for both ursocholanic acid and ursodeoxycholic acid in a Parkin-deficient neuronal model system. Of note, both ursocholanic acid and ursodeoxycholic acid also rescued mitochondrial function in LRRK2(G2019S) mutant fibroblasts. Our study demonstrates the feasibility of undertaking drug screens in Parkinson's disease patients' tissue and has identified a group of chemically-related compounds with marked mitochondrial rescue effect. Drug repositioning is considered to be a time- and cost-saving strategy to assess drugs already licensed for a different condition for their neuroprotective effect. We therefore propose both ursolic acid as a naturally occurring compound, and ursodeoxycholic acid as an already licensed drug as promising compounds for future neuroprotective trials in Parkinson's disease.