Quantification of the dopaminergic response in Parkinson's disease

Distinct cortical and subcortical predictors of Purdue Pegboard decline in Parkinson's disease and atypical parkinsonism

Objective measures of disease progression are critically needed in research on Parkinson's disease (PD) and atypical Parkinsonism but may be hindered by both practicality and cost. The Purdue Pegboard Test (PPT) is objective, has high test-retest reliability, and has a low cost. The goals of this study were to determine: (1) longitudinal changes in PPT in a multisite cohort of patients with PD, atypical Parkinsonism, and healthy controls; (2) whether PPT performance reflects brain pathology revealed by neuroimaging; (3) quantify kinematic deficits shown by PD patients during PPT. Parkinsonian patients showed a decline in PPT performance that correlated with motor symptom progression, which was not seen in controls. Neuroimaging measures from basal ganglia were significant predictors of PPT performance in PD, whereas cortical, basal ganglia, and cerebellar regions were predictors for atypical Parkinsonism. Accelerometry in a subset of PD patients showed a diminished range of acceleration and irregular patterns of acceleration, which correlated with PPT scores.

Predicting Long-Term Outcome of Patients of Early Parkinsonism with Acute Levodopa Challenge Test

Objectives

The aim of this study was to evaluate the sensitivity and specificity of various outcomes of acute levodopa challenge test (ALCT) namely improvement of motor function, development of dyskinesia and intolerance; to predict the diagnosis of idiopathic Parkinson's disease (IPD) or Parkinson-plus syndrome; to predict levodopa responsiveness and levodopa-induced dyskinesia (LID) during long-term therapy.

Methods

ALCT was performed on 89 patients with parkinsonism of <2 years and were followed up for 18 months. Improvement of UPDRSm by ≥30% was considered positive.

Results

The test was positive in 37 (43.5%) and negative in 48 (56.5%) of 85 patients completing it. Of the 75 patients completing 18 months' follow-up 34 (45.3%) were diagnosed as IPD. A positive ALCT predicted a clinical diagnosis of IPD with sensitivity and specificity of 97.4% and 70.7% respectively. The predictive value of ALCT for long-term levodopa responsiveness was less than predicting a diagnosis of IPD. While appearance of dyskinesia during ALCT had a low predictive value for future LID (sensitivity 14.3%), it had high predictive value for a diagnosis of multisystem atrophy (MSA) (91% specificity and 37.5% sensitivity). The appearance of symptoms of levodopa intolerance (SLI) during ALCT could predict a clinical diagnosis of MSA with high specificity (95.5%) and moderate sensitivity (50%).

Conclusion

Levodopa responsiveness during ALCT was useful in predicting a diagnosis of IPD but not long-term response to levodopa. The development of dyskinesia during ALCT could not correctly predict LID, but could predict a diagnosis of MSA. The appearance of SLI during ALCT could also predict MSA correctly.

Levodopa challenge test: indications, protocol, and guide

A drug challenge test in Parkinson's disease, such as the levodopa challenge test (LCT), is an easy and generally safe procedure, which has been used by clinicians for various indications. The results of the test have significant implications in the management of patients, from preoperative evaluation for deep brain stimulation to providing the basis for medication adjustments to address motor or non-motor fluctuations and dyskinesias. This paper reviews the different indications and protocols commonly used in an acute LCT. Potential complications of the procedure and an overview of levodopa responsiveness and unresponsiveness are also discussed.

Different response to instrumental tests in relation to cognitive demand after dopaminergic stimulation in previously treated patients with Parkinson's disease

Instrumental measurement of response assets and movement behaviour gained importance as addition to rating procedures to determine the efficacy of therapeutic interventions in patients with Parkinson's disease. Objectives were to determine the response to standardised 100 mg levodopa application with repeat performance of complex and simple instrumental tests in relation to scored motor behaviour in 53 previously treated patients. Levodopa improved rating scores of motor impairment, execution of complicated movement patterns and complex reaction time. Computed improvements in these instrumental test results correlated with each other. Execution of the simple reaction time paradigm and of plain movement sequences did not ameliorate after levodopa. The changes of these simple test results were not associated to each other. These different response patterns result from the higher cognitive demand of dopamine sensitive association areas of the prefrontal cortex and mesolimbic system for the complex test execution in contrast to the simple task performance.

Impaired finger dexterity and nigrostriatal dopamine loss in Parkinson's disease

Impaired finger dexterity occurs in Parkinson's disease (PD) and has been considered a limb-kinetic apraxia associated with primary sensory cortical dysfunction. To study the role of nigrostriatal dopamine loss and elementary parkinsonian motor deficits in impaired finger dexterity of PD. Thirty-two right-handed untreated PD patients and 30 right-handed healthy controls were included. All patients underwent [¹⁸F] FP-CIT positron emission tomography studies. We examined the associations among unilateral coin rotation (CR) score, Unified Parkinson's Disease Rating Scale (UPDRS) subscores for bradykinesia and rigidity of the corresponding arm, and contralateral regional striatal dopamine transporter (DAT) uptake. We also measured the effect of oral levodopa dose on CR scores and UPDRS subscores. PD patients performed worse than controls on the CR task. Unilateral arm UPDRS bradykinesia scores were associated with DAT uptake in the contralateral putamen. The left CR score was associated with left arm bradykinesia and rigidity scores and DAT uptake in the right posterior putamen, whereas no such associations were found for the right CR score. There was a significant effect of handedness on the association of putamen DAT uptake with CR scores, but not with UPDRS subscores. An oral levodopa challenge improved CR scores and UPDRS subscores on both sides. Impaired finger dexterity in PD is related to elementary parkinsonian motor deficits and nigrostriatal dopamine loss. Impaired dominant hand dexterity associated with nigrostriatal dopamine loss seems to be compensated to some extent by the dominant cerebral cortex specialized for controlling precise finger movements.

Aerobic exercise and attention deficit hyperactivity disorder: brain research

PURPOSE

As adjuvant therapy for enhancing the effects of stimulants and thereby minimizing medication doses, we hypothesized that aerobic exercise might be an effective adjunctive therapy for enhancing the effects of methylphenidate on the clinical symptoms, cognitive function, and brain activity of adolescents with attention deficit hyperactivity disorder (ADHD).

METHODS

Thirty-five adolescents with ADHD were randomly assigned to one of two groups in a 1/1 ratio; methylphenidate treatment + 6-wk exercise (sports-ADHD) or methylphenidate treatment + 6-wk education (edu-ADHD). At baseline and after 6 wk of treatment, symptoms of ADHD, cognitive function, and brain activity were evaluated using the Dupaul attention deficit hyperactivity disorder rating scale--Korean version (K-ARS), the Wisconsin Card Sorting Test, and 3-T functional magnetic resonance imaging, respectively.

RESULTS

The K-ARS total score and perseverative errors in the sports-ADHD group decreased compared with those in the edu-ADHD group. After the 6-wk treatment period, the mean β value of the right frontal lobe in the sports-ADHD group increased compared with that in the edu-ADHD group. The mean β value of the right temporal lobe in the sports-ADHD group decreased. However, the mean β value of the right temporal lobe in the edu-ADHD group did not change. The change in activity within the right prefrontal cortex in all adolescents with ADHD was negatively correlated with the change in K-ARS scores and perseverative errors.

CONCLUSIONS

The current results indicate that aerobic exercise increased the effectiveness of methylphenidate on clinical symptoms, perseverative errors, and brain activity within the right frontal and temporal cortices in response to the Wisconsin card sorting test stimulation.

Graphical Tasks to Measure Upper Limb Function in Patients With Parkinson's Disease: Validity and Response to Dopaminergic Medication

The most widely used method to assess motor functioning in Parkinson's disease (PD) patients is the unified Parkinson's disease rating scale-III (UPDRS-III). The UPDRS-III has limited ability to detect subtle changes in motor symptoms. Alternatively, graphical tasks can be used to provide objective measures of upper limb motor dysfunction. This study investigated the validity of such graphical tasks to assess upper limb function in PD patients and their ability to detect subtle changes in performance. Fourteen PD patients performed graphical tasks before and after taking dopaminergic medication. Graphical tasks included figure tracing, writing, and a modified Fitts' task. The Purdue pegboard test was performed to validate these graphical tasks. Movement time (MT), writing size, and the presence of tremor were assessed. MT on the graphical tasks correlated significantly with performance on the Purdue pegboard test (Spearman's ρ > 0.65; p < 0.05). MT decreased significantly after the intake of dopaminergic medication. Tremor power decreased after taking dopaminergic medication in most PD patients who suffered from tremor. Writing size did not correlate with performance on the Purdue pegboard test, nor did it change after taking medication. Our set of graphical tasks is valid to assess upper limb function in PD patients. MT proved to be the most useful measure for this purpose. The response on dopaminergic medication was optimally reflected by an improved MT on the graphical tasks in combination with a decreased tremor power, whereas writing size did not respond to dopaminergic treatment.

The impact of restless legs syndrome on physical functioning in a community-dwelling population of middle-aged and elderly people

OBJECTIVE

To investigate whether restless legs syndrome (RLS) is associated with impaired physical functioning using subjective and objective assessments.

METHODS

From 2006-2013, 5,960 participants (mean age 67.2; 57.5% females) of the prospective population-based Rotterdam Study, aged 45 years and over, were cross-sectionally investigated for presence of restless legs syndrome using a questionnaire. Physical functioning was assessed subjectively with the Stanford Health Assessment Questionnaire (basic activities of daily living) and the Instrumental Activities of Daily living scale (instrumental activities of daily living). Additionally, physical functioning was assessed objectively by quantifying fine motor performance with the Purdue Pegboard Test and by quantifying gait with an electronic walkway.

RESULTS

Restless legs syndrome was present in 13.7% of the participants. Persons with restless legs had more impairment in basic (difference in score 0.65, 95% CI 0.41;0.90) and instrumental activities of daily living (difference in score 0.28, 95% CI 0.09;0.48) than persons without restless legs. This association was strongest when symptoms were present two or more times a week (basic activities of daily living score difference 1.69, 95% CI 1.28;2.09). The association between restless legs syndrome and activities of daily living attenuated after adjusting for sleep quality or depressive symptoms. There was no association with the Purdue Pegboard Test score nor with gait.

CONCLUSIONS

Individuals with restless legs syndrome experienced significantly more impairment in activities of daily function than persons without restless legs. This seemed to be (partly) mediated by poor sleep quality and depressive symptoms. No association was found with objectively assessed physical functioning.

Entacapone improves complex movement performance in patients with Parkinson’s disease

BACKGROUND

A possible strategy to prolong plasma metabolism of Levodopa/Carbidopa (LD/CD) is Entacapone addition (EN), which improves impaired motor behaviour in patients with Parkinson's disease (PD).

AIMS OF THE STUDY

Objectives were to evaluate the clinical response to an increased dopaminergic substitution with EN by clinical rating and assessment of complex motions and to investigate the change of movement in PD patients during repeat drug administration during an eight hour interval.

METHODS

We used peg insertion with a computer based device and clinical rating for assessment of motor function in 20 treated PD patients. They received LD/CD and then the same LD/CD dosage plus EN in a standardised, open label fashion.

RESULTS

Motor scores and performance of the instrumental task were significantly better and the fluctuation of movement was less intense during the LD/CD/EN condition according to the motor test outcomes.

CONCLUSION

EN supplementation improves motor symptoms and provides a more continuous movement behaviour in PD patients.

Inhibition of catechol-O-methyltransferase contributes to more stable levodopa plasma levels

The short plasma half-life limits the antiparkinsonian efficacy of levodopa/carbidopa (LD/CD). Administration of LD/CD with the catechol-O-methyltransferase inhibitor entacapone in one tablet (LCE) may extend plasma half-life of LD and thus its effect on motor symptoms in patients with Parkinson's disease (PD). The objectives of this study were to monitor the motor response to a switch from LD/CD to LCE by a simultaneous performance of an instrumental motor test and rating of motor symptoms and to compare the LD plasma behavior between both conditions in terms of stability. Twenty-one treated PD patients received LD/CD and then the identical oral LD dosage of LCE within a standardized setting on 2 consecutive days. Rating better reflected the motor improvement after LD application than the instrumental test. Motor symptoms of PD patients decreased significantly more during the LCE than the LD/CD condition, probably due to significantly higher LD plasma levels and a significantly less pronounced fall of the LD concentrations following the second LD intake. Our study shows a more stable LD plasma behavior during LCE intake and accordingly a better effect on motor symptoms according to rating outcomes and motor test results to a lesser extent.

Simple movement sequences better correlate to levodopa plasma levels than complex ones

Instrumental assessment of movements with a computer based device reflect the clinical response of patients with Parkinson's disease (PD) to dopaminergic stimulation. We investigated associations between levodopa plasma levels, scored motor symptoms of upper limbs and instrumental test outcomes after dopaminergic stimulation. Clinical rating scores, test outcomes for simple and complex motion series significantly improved after oral application of 250 mg of a water soluble, fast absorbed levodopa/benserazide preparation, which induced a significant increase of levodopa in plasma during a two hour interval. There was a significant association between the computed area under the curve-values of levodopa plasma concentrations and test results for simple-, but not for complex movement sequences. Performance of complex motion series additionally ask for concomitant cognitive efforts with consecutive hypothetical involvement of extranigral non dopaminergic systems. In contrast, practice of simple movements is more directly associated to the predominantly dopamine regulated motor system.

Treatment benefit and daily drug costs associated with treating Parkinson's disease in a Parkinson's disease clinic

OBJECTIVE

In some countries, such as Germany, there has been a move towards the treatment of patients with Parkinson's disease in specialised inpatient units. However, data on patient outcome and the daily costs of antiparkinsonian drugs in these settings are rare. This study was conducted to determine the effect of an inpatient setting (a specialised Parkinson's disease clinic) on drug therapy costs and patient symptoms.

PATIENTS AND METHODS

This study involved 63 consecutively referred inpatients of a Parkinson's disease clinic. On entry to the clinic, the patients' antiparkinsonian drug regimen was titrated in order to improve their motor function. The daily costs of drug therapy per patient (in 2002 values) were calculated, and the severity of Parkinson's disease symptoms scored via scores on the Unified Parkinson's Disease Rating Scale (UPDRS) and standardised instrumental procedures (peg insertion and tapping), both initially and at the end of the patients' stay in the clinic. The variables between the two evaluation timepoints were compared.

RESULTS

The titration of antiparkinsonian drugs was associated with a significant decrease in the symptoms of Parkinson's disease at discharge from the clinic compared with admission (as measured by UPDRS total and subscale scores [all p < 0.001], and, to a lesser extent, by peg insertion and tapping [both p < 0.05]). A significant increase in daily drug costs (an increase of euro14.11 per patient for all drugs and euro12.36 per patient for antiparkinsonian drugs [both p <0.001]) was also observed.

CONCLUSION

The results demonstrate that the symptoms experienced by patients with Parkinson's disease improve after performance of antiparkinsonian drug titration within the setting of a specialised Parkinson's disease clinic. The effect on symptoms was seen most clearly with the UPDRS, although both peg insertion and tapping reflected this improvement to a certain extent. Drug titration resulted in, on average, a doubling of daily drug costs. Future trials are needed to investigate the long-term effects of such a hospital stay on indirect costs associated with treating Parkinson's disease, and on caregiver burden, and also to compare the efficacy of a Parkinson's disease clinic with an outpatient setting.

Motor impairment influences Farnsworth-Munsell 100 Hue test error scores in Parkinson's disease patients

Farnsworth-Munsell 100 Hue test (FMT) error scores and peg insertion abilities significantly differ between Parkinson's disease (PD) patients and controls. Both tasks ask for performance of voluntary movements. The objective of this study was to demonstrate a relation between FMT error scores and peg insertion outcomes. We successively performed both tasks in 28 previously untreated PD patients. The FMT error score was significantly (p=0.016) lower in patients with better peg insertion outcome. A significant (Spearman R=0.47, p=0.012) correlation between peg insertion results and the FMT error scores appeared. Motor impairment influences FMT error scores in PD patients.