Another face of placebo: the lessebo effect in Parkinson disease: meta-analyses

Dilemmas in diagnosing Alzheimer's disease: The peril and promise of self-fulfilling prophecies

To date, there are limited empirical data to inform various approaches to communication with patients receiving information on Alzheimer's disease (AD) risk or diagnosis during the pre-symptomatic or minimally symptomatic stages. This article explores the ethical implications of psychological responses known as self-fulfilling prophecies that may impact cognitive decline among individuals diagnosed with or at risk for AD. We describe questions these potential effects raise about the ways clinicians communicate with patients, as well as how caregivers may interact with patients. Recent advancements in biomarkers and treatment for AD underscore the urgency of understanding these phenomena and developing appropriate responses.

Multi-omics characterization of improved cognitive functions in Parkinson's disease patients after the combined metabolic activator treatment: a randomized, double-blinded, placebo-controlled phase II trial

Parkinson's disease is primarily marked by mitochondrial dysfunction and metabolic abnormalities. We recently reported that the combined metabolic activators improved the immunohistochemical parameters and behavioural functions in Parkinson's disease and Alzheimer's disease animal models and the cognitive functions in Alzheimer's disease patients. These metabolic activators serve as the precursors of nicotinamide adenine dinucleotide and glutathione, and they can be used to activate mitochondrial metabolism and eventually treat mitochondrial dysfunction. Here, we designed a randomized, double-blinded, placebo-controlled phase II study in Parkinson's disease patients with 84 days combined metabolic activator administration. A single dose of combined metabolic activator contains L-serine (12.35 g), N-acetyl-L-cysteine (2.55 g), nicotinamide riboside (1 g) and L-carnitine tartrate (3.73 g). Patients were administered either one dose of combined metabolic activator or a placebo daily for the initial 28 days, followed by twice-daily dosing for the next 56 days. The main goal of the study was to evaluate the clinical impact on motor functions using the Unified Parkinson's Disease Rating Scale and to determine the safety and tolerability of combined metabolic activator. A secondary objective was to assess cognitive functions utilizing the Montreal Cognitive Assessment and to analyse brain activity through functional MRI. We also performed comprehensive plasma metabolomics and proteomics analysis for detailed characterization of Parkinson's disease patients who participated in the study. Although no improvement in motor functions was observed, cognitive function was shown to be significantly improved (P < 0.0000) in Parkinson's disease patients treated with the combined metabolic activator group over 84 days, whereas no such improvement was noted in the placebo group (P > 0.05). Moreover, a significant reduction (P = 0.001) in Montreal Cognitive Assessment scores was observed in the combined metabolic activator group, with no decline (P > 0.05) in the placebo group among severe Parkinson's disease patients with lower baseline Montreal Cognitive Assessment scores. We showed that improvement in cognition was associated with critical brain network alterations based on functional MRI analysis, especially relevant to areas with cognitive functions in the brain. Finally, through a comprehensive multi-omics analysis, we elucidated the molecular mechanisms underlying cognitive improvements observed in Parkinson's disease patients. Our results show that combined metabolic activator administration leads to enhanced cognitive function and improved metabolic health in Parkinson's disease patients as recently shown in Alzheimer's disease patients. The trial was registered in ClinicalTrials.gov NCT04044131 (17 July 2019, https://clinicaltrials.gov/ct2/show/NCT04044131).

Evidence and sources of placebo effects in transcranial direct current stimulation during a single session of visuospatial working memory practice

Transcranial direct current stimulation (tDCS) can be used to non-invasively augment cognitive training. However, the benefits of tDCS may be due in part to placebo effects, which have not been well-characterized. The purpose of this study was to determine whether tDCS can have a measurable placebo effect on cognitive training and to identify potential sources of this effect. Eighty-three right-handed adults were randomly assigned to one of three groups: control (no exposure to tDCS), sham tDCS, or active tDCS. The sham and active tDCS groups were double-blinded. Each group performed 20 min of an adapted Corsi Block Tapping Task (CBTT), a visuospatial working memory task. Anodal or sham tDCS was applied during CBTT training in a right parietal-left supraorbital montage. After training, active and sham tDCS groups were surveyed on expectations about tDCS efficacy. Linear mixed effects models showed that the tDCS groups (active and sham combined) improved more on the CBTT with training than the control group, suggesting a placebo effect of tDCS. Participants' tDCS expectations were significantly related to the placebo effect, as was the belief of receiving active stimulation. This placebo effect shows that the benefits of tDCS on cognitive training can occur even in absence of active stimulation. Future tDCS studies should consider how treatment expectations may be a source of the placebo effect in tDCS research, and identify ways to potentially leverage them to maximize treatment benefit.

The Lessebo Effect in Disease Modification Trials in Parkinson's Disease

BACKGROUND

The impact of expectation of benefit on outcomes is well established in Parkinson's disease (PD). A reduction of a treatment effect due to a perceived placebo allocation (lessebo effect) in randomized controlled trials (RCTs) was documented for symptomatic treatments.

OBJECTIVES

To evaluate the lessebo effect in disease modification RCTs (DMT) in PD.

METHODS

Subject-level meta-analyses of active treatment arms of DMT (n = 1149 subjects): FS-1, FS-TOO (probability of placebo allocation/P_(placebo)  = 0.33) and DATATOP, PRECEPT, QE2 (P_(placebo)  = 0.25). We tested the association between P_(placebo) and time to dopaminergic treatment initiation using a marginal Cox proportional hazards model.

RESULTS

The adjusted hazard ratio (P_(placebo)  = 0.25 vs. 0.33) for initiation of dopaminergic treatment was 1.15 (95% CI: 0.92-1.43).

CONCLUSIONS

We did not observe the lessebo effect in DMT. The necessary use of a placebo (and no active comparator) is a limitation. The prospective measurement of expectation of benefit could help to evaluate the many impacts of placebo use. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The lessebo effect in randomized controlled trials of rituximab in patients with rheumatoid arthritis: a meta-analysis

OBJECTIVE

The goal of this study was to assess the impact of negative expectations associated with receiving a placebo (the lessebo effect) on efficacy outcomes in randomized clinical trials (RCTs) of rituximab in patients with rheumatoid arthritis (RA).

METHODS

We performed a meta-analysis on the American College of Rheumatology 20%, 50%, and 70% (ACR20, 50, 70) response rates in the placebo and active (biosimilar)-controlled groups (reference-pbo and reference-bs) of rituximab showing an insufficient response to methotrexate or tumor necrosis factor. We evaluated the difference in ACR20, 50, 70 response rates between the two groups (reference-bs vs. reference-pbo).

RESULTS

Nine RCTs included a total of 2734 patients with RA. The pooled incidence of ACR20 response rate in the placebo- and active-controlled groups of the rituximab RCTs for RA was 53.1% (95% confidence interval [CI] 49.9-56.3%) and 75.0% (95% CI 71.2-78.4%), respectively. The difference in the ACR20 response rate between the placebo- and active-controlled groups was -20.9% (95% CI -26.9 to 61.9%, p < 0.001). The pooled incidence of ACR50 response rate in the placebo- and active-controlled groups of the rituximab RCTs for RA was 29.0% (95% CI 26.2-32.0%) and 47.4% (95% CI 43.2-51.6%), respectively. The ACR50 response rates were significantly higher in the active-controlled groups than in the placebo-controlled groups (-18.4%; 95% CI -18.4 to -13.4%, p < 0.001). The difference in the ACR70 response rate between the placebo- and active-controlled groups was -14.9% (95% CI -22.2 to -7.6%, p < 0.001). The ACR20, 50, 70 response rates were significantly higher in the active-controlled groups than in the placebo-controlled group.

CONCLUSION

This study shows that the use of a placebo can be associated with a clinically significant reduction in the magnitude of change of the ACR20, 50, 70 response rates in rituximab RCTs for RA. The lessebo effect has potential implications for the development of new treatments and appraisal of current treatment options for RA.

Placebo and nocebo effects: from observation to harnessing and clinical application

Placebo and nocebo effects are salubrious benefits and negative outcomes attributable to non-specific symbolic components. Leveraging advanced experimental and analytical approaches, recent studies have elucidated complicated neural mechanisms that may serve as a solid basis for harnessing the powerful self-healing and self-harming capacities and applying these findings to improve medical practice and minimize the unintended exacerbation of symptoms in medical practice. We review advances in employing psychosocial, pharmacological, and neuromodulation approaches to modulate/harness placebo and nocebo effects. While these approaches show promising potential, translating these research findings into clinical settings still requires careful methodological, technical, and ethical considerations.

Different symptomatic improvement pattern revealed by factor analysis between placebo response and response to Esketamine in treatment resistant depression

AIMS

The aim of this study is to determine whether there is difference in the change in each symptom of depression and in symptomatic improvement pattern between placebo and antidepressant responses.

METHODS

Using data from a randomized, double-blind (DB), placebo-controlled trial of esketamine (ESK) in patients with treatment-resistant depression (TRD), we conducted exploratory analyses. To determine differences in the change in each depressive symptom on the MADRS subscale between placebo and antidepressant responses, a two-way factorial analysis was conducted using the amount of change on Day 2 and 28 of treatment. In addition, exploratory and confirmatory factor analyses were conducted on the MADRS subtotal variables on Day 2 and 28 of treatment to determine symptomatic improvement pattern between placebo response and antidepressant responses.

RESULTS

We found that as well as MADRS total score, each subscale of MADRS score did not significantly differ between esketamine and placebo at Day 2 and 28. On the other hand, factor analysis revealed that the factor structure of the response was different between esketamine and placebo at the 2nd day. There was no difference in the factor structure between esketamine and placebo in response on Day 28 of treatment.

CONCLUSION

Factor analysis revealed different patterns of symptom improvement in the early phase of the intervention between esketamine and placebo. This finding suggests that a data driven approach may provide detailed efficacy information in clinical trials for antidepressants.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02918318. Registered: 28 September 2016.

Effects of nabilone on sleep outcomes in patients with Parkinson's disease: a post‐hoc analysis of NMS‐Nab study

Background

The synthetic tetrahydrocannabinol analogue nabilone improved overall non‐motor symptom (NMS) burden in Parkinson's disease (PD) patients in comparison to placebo.

Objectives

To characterize the effects of nabilone on different sleep outcomes in PD patients.

Methods

We performed a post‐hoc analysis of the controlled, double‐blind, enriched enrollment randomized withdrawal NMS‐Nab study to assess the effects of nabilone on sleep outcomes in study participants who reported clinically‐relevant sleep problems (MDS‐UPDRS‐1.7 ≥ 2 points).

Results

After open‐label nabilone administration, 77.4% reported no relevant sleep problem. In the withdrawal phase of the trial, the MDS‐UPDRS‐1.7. and the NMS‐Scale Domain 2 (i.e., Sleep/Fatigue) significantly worsened only in PD patients in the placebo group, which was mostly driven by a significant worsening of insomnia (question 5 of the NMS‐Scale Domain 2).

Conclusions

This post‐hoc analysis of the NMS‐Nab trial suggests that nabilone has beneficial effects on sleep outcomes in PD patients experiencing sleep problems at baseline.

The original trial was registered with ClinicalTrials.gov (NCT03769896, https://clinicaltrials.gov/ct2/show/NCT03769896) and EudraCT (2017–000192‐86).

Methodological Considerations for Setting Up Deep Brain Stimulation Studies for New Indications

Deep brain stimulation (DBS) is a neurosurgical treatment with a growing range of indications. The number of clinical studies is expanding because of DBS for new indications and efforts to improve DBS for existing indications. To date, various methods have been used to perform DBS studies. Designing a clinical intervention study with active implantable medical devices has specific challenges while expanding patient treatment. This paper provides an overview of the key aspects that are essential for setting up a DBS study.

What is the role of placebo in neurotherapeutics?

INTRODUCTION

The widespread use of the word 'placebo' in the medical literature emphasizes the importance of this phenomenon in modern biomedical sciences. Neuroscientific research over the past thirty years shows that placebo effects are genuine psychobiological events attributable to the overall therapeutic context, and can be robust in both laboratory and clinical settings.

AREAS COVERED

Here the authors describe the biological mechanisms and the clinical implications of placebo effects with particular emphasis on neurology and psychiatry, for example in pain, movement disorders, depression. In these conditions, a number of endogenous systems have been identified, such as endogenous opioids, endocannabinoids, and dopamine, which contribute to the placebo-induced benefit.

EXPERT OPINION

Every effort should be made to maximize the placebo effect and reduce its evil twin, the nocebo effect, in medical practice. This does not require the administration of a placebo, but rather the enhancement of the effects of pharmacological and nonpharmacological treatments through a good doctor-patient interaction.

The response to TNF blockers depending on their comparator in rheumatoid arthritis clinical trials: the lessebo effect, a meta-analysis

OBJECTIVE

To compare the effect of the biological reference agents (infliximab, etanercept, adalimumab) in rheumatoid arthritis (RA) in pivotal superiority placebo-controlled trials (reference agent vs placebo) vs their effect in equivalence active comparator-controlled trials (reference agent vs biosimilar).

METHODS

The PubMed, EMBASE, Cochrane, databases were searched for randomized, double-blind, controlled trials up to March 2020 comparing a biological reference agent vs placebo or biosimilar. The study assessed the American College of Rheumatology (ACR) 20/50/70 responses of the reference agent in these groups (Reference-pbo and Reference-bs, respectively). The effect of the reference agent in both groups was estimated with 95% confidence intervals (95%CI), pooled using random-effects models and then compared using a meta-regression model.

RESULTS

We included 31 trials. The main characteristics of the population (disease duration and activity, % seropositivity and methotrexate dose) of the population in both groups were similar. The meta-analysis found a better ACR20 response to the biological originator in the Reference-bs group with a global rate of 70% (95%CI, 66-74) compared with 59% (95%CI, 55-62) in the reference-pbo group (p= 0.001). A significant difference was also found for ACR 50 [44% (95%CI, 39-50) vs 35% (95%CI, 31-39) respectively, p< 0.01].

CONCLUSION

Effect of the reference biologic agent was better when compared with an active drug to a placebo. This could be linked to an increased placebo effect in active comparator-controlled studies or a nocebo effect in placebo-controlled studies. This effect can be called the Lessebo effect.

Subjective cognition and mood in persistent chemotherapy-related cognitive impairment

PURPOSE

Persistent chemotherapy-related cognitive impairment (CRCI) is commonly reported following cancer treatment and negatively affects quality of life. While past research has focused on potential pathophysiological mechanisms underlying this relationship, the role of psychological factors, such as mood, stress, and anxiety, in the development of persistent CRCI has received less attention. As an additional analysis of data from a trial investigating the effects of transdermal nicotine patches on cognitive performance in patients with persistent CRCI, we examined whether change in mood was associated with changes in subjective and objective cognitive functioning.

METHODS

Participants were randomized to either placebo (n = 11) or transdermal nicotine (n = 11) for 6 weeks, followed by 2 weeks of treatment withdrawal for a total of 8 weeks. Participants were assessed using behavioral, subjective, and objective measures of cognitive functioning and mood at five visits before, during, and after treatment.

RESULTS

Although we did not detect an effect of treatment assignment on mood, over the course of the study, we observed a significant improvement on measures of mood that correlated with improvement in subjective and objective cognitive performance.

CONCLUSIONS

We observed improvement in objective and subjective cognitive performance measures. These changes were associated with improvement in subsyndromal mood symptoms, likely resulting from participation in the trial itself.

IMPLICATIONS FOR CANCER SURVIVORS

These results suggest that women with persistent CRCI may benefit from support and validation of their cognitive complaints, cognitive rehabilitation/therapies into their post-cancer care.

TRIAL REGISTRATION

The study was registered with clinicaltrials.gov (trial registration: NCT02312943).

Sociability-based fitness approach in Parkinson's disease: Comparison with conventional rehabilitation

BACKGROUND AND PURPOSE

The effect of a sociability-based fitness approach on parkinsonian disability in patients with Parkinson's disease (PD) was assessed.

METHODS

Eighty patients diagnosed with PD were randomly assigned to either the group-based rehabilitation (GBR) group (n = 40) or the individual-based rehabilitation (IBR) group (n = 40). The primary outcome was the difference between the two groups in the mean change from baseline to post-training in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS). The secondary outcomes included the change in mental status and the difference in the mean change from baseline to month 3 and month 6 in the total score on the UPDRS.

RESULTS

The mean (±SD) UPDRS scores were 72.0 ± 21.0 in the GBR group and 72.1 ± 18.6 in the IBR group. The UPDRS scores from baseline to post-training were 22.8 ± 13.5 in the GBR group and 10.9 ± 8.8 in the IBR group (difference 11.8 points; 95% confidence interval [CI] 5.0-18.6; p = 0.001). The difference between the groups from baseline to month 3 (difference 10.06 points; 95% CI 3.3-16.8) and the difference between the groups from baseline to month 6 (difference 11.7 points; 95% CI 4.9-18.5) were also significant (p = 0.004 and p = 0.001, respectively). The scores of cognitive function and depression had not changed significantly.

CONCLUSIONS

Patients receiving GBR demonstrated significant improvements in parkinsonian symptoms, suggesting that the sociability-based fitness can be applied to clinical treatment by sustaining the motivation in PD.

Acute Exercise-Induced Set Shifting Benefits in Healthy Adults and Its Moderators: A Systematic Review and Meta-Analysis

Background: Positive effects of acute exercise on cognitive performances in general inspired research that investigated the effects of acute exercise on specific cognitive subdomains. Many existing studies examined beneficial effects of acute exercise on subsequent set shifting performance in healthy adults. Set shifting, a subdomain of executive function, is the ability to switch between different cognitive sets. The results of existing studies are inconsistent. Therefore, a meta-analysis was conducted that pooled available effect sizes. Additionally, moderator analyses were carried out to identify covariates that determine the magnitude of exercise-induced set shifting benefits.

Methods: Medline, PsycINFO, and SPORTDiscus were searched for eligible studies. Hedges' g corrected standardized mean difference values were used for analyses. Random-effects weights were applied to pool effects. Potential moderation of the effect of acute exercise on subsequent set shifting performance by exercise intensity, type of exercise, participants' age, and type of control group were examined.

Results: Twenty-two studies (N = 1,900) were included into analysis. All aggregated effect sizes ranged from small to moderate. Overall, a small significant beneficial effect was revealed (g = −0.32, 95 % CI −0.45 to −0.18). Heterogeneity of included effect sizes was moderate and significant (T² = 0.0715, I² = 46.4%, (p < 0.0016). Moderator analyses revealed a larger average effect in older adults than for studies examining younger adults (−0.42 vs. −0.29). Light exercise (−0.51) led to larger effects than moderate (−0.24) or vigorous exercise (−0.29). Studies testing acute exercise against active control groups showed a noticeably smaller average effect (−0.13) than studies that used passive (−0.38) or cognitive engaging control groups (−0.34). Interestingly, application of resistance or aerobic exercise led to no different average effect sizes (−0.30 vs. −0.32). However, none of the tested covariates reached statistical significance.

Conclusion: Acute exercise improves subsequent set shifting performance. However, effect sizes are small, making the relevance for everyday life questionable. The results indicate that older adults benefit more from acute exercise than younger adults do. Light intensity exercise seems most effective while the type of exercise does not seem to influence the magnitude of effects. Research designs with active control groups show the smallest average effect, raising concerns about placebo effects.

PROSPERO registration number: CRD42019138799

Double-Blind, Randomized, Placebo-Controlled Trial of DA-9701 in Parkinson's Disease: PASS-GI Study

OBJECTIVES

This study aimed to assess the efficacy of DA-9701 on gastrointestinal symptom-related quality of life in patients with Parkinson's disease on stable dopaminergic medications.

METHODS

This multicenter, double-blind, placebo-controlled, phase 4 trial included a total of 144 patients with Parkinson's disease with gastrointestinal dysfunctions based on predefined criteria. Participants were randomized to take either DA-9701 or placebo for 4 weeks, and then both groups were administered DA-9701 for an additional 8 weeks while antiparkinsonian medications were unchanged. The primary outcome measure was gastrointestinal symptoms and related quality-of-life changes assessed on the Korean Nepean dyspepsia index after 4 and 12 weeks of therapy. We also evaluated the impact of DA-9701 therapy on parkinsonian motor symptoms at each time point.

RESULTS

The gastrointestinal symptom-related quality-of-life score significantly improved in the DA-9701-treated group compared with the placebo-treated group after 4weeks (adjusted P = 0.012 by linear mixed effect model analysis). The overall gastrointestinal symptom and dyspepsia sum scores improved at 12 weeks after intervention in the DA-9701-first treated group (adjusted P = 0.002 and 0.014, respectively) and also in the placebo-first treated group (adjusted P = 0.019 and 0.039) compared with the baseline. Parkinsonian motor severity was not significantly affected by DA-9701 treatment in both groups at 4 and 12 weeks after intervention. There were no drug-related serious adverse events throughout the trial.

CONCLUSIONS

DA-9701 therapy improved gastrointestinal symptom-related quality of life, and 12 weeks of daily administration can relieve the overall severity of gastrointestinal symptoms in patients with Parkinson's disease without affecting motor symptoms. (Clinical trial identifier: NCT02775591.) © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Non-Motor Symptoms in Parkinson's Disease are Reduced by Nabilone

OBJECTIVE

The objective of this study was to assess the efficacy and safety of nabilone, a synthetic tetrahydrocannabinol analogue, as a treatment for non-motor symptoms (NMS) in Parkinson's disease (PD).

METHODS

This was a phase II placebo-controlled, double-blind, parallel-group, enriched enrollment randomized withdrawal trial conducted at the Medical University Innsbruck. A random sample of 47 patients with PD with stable motor disease and disturbing NMS defined by a score of ≥4 points on the Movement Disorder Society - Unified PD Rating Scale-I (MDS-UPDRS-I) underwent open-label nabilone titration (0.25 mg once daily to 1 mg twice daily, phase I). Responders were randomized 1:1 to continue with nabilone or switch to placebo for 4 weeks (phase II). The primary efficacy criterion was the change of the MDS-UPDRS-I between randomization and week 4. Safety was analyzed in all patients who received at least one nabilone dose.

RESULTS

Between October 2017 and July 2019, 19 patients received either nabilone (median dose = 0.75 mg) or placebo. At week 4, mean change of the MDS-UPDRS-I was 2.63 (95% confidence interval [CI] 1.53 to 3.74, p = 0.002, effect size = 1.15) in the placebo versus 1.00 (95% CI -0.16 to 2.16, p = 0.280, effect size = 0.42) in the nabilone-group (difference: 1.63, 95% CI 0.09 to 3.18, p = 0.030, effect size = 0.66). Seventy-seven percent of patients had adverse events (AEs) during open-label titration, most of them were transient. In the double-blind phase, similar proportions of patients in each group had AEs (42% in the placebo group and 32% in the nabilone group). There were no serious AEs.

INTERPRETATION

Our results highlight the potential efficacy of nabilone for patients with PD with disturbing NMS, which appears to be driven by positive effects on anxious mood and night-time sleep problems.

TRIAL REGISTRY

ClinicalTrials.gov (NCT03769896) and EudraCT (2017-000192-86). ANN NEUROL 2020;88:712-722.

The Adapted Resistance Training with Instability Randomized Controlled Trial for Gait Automaticity

BACKGROUND

Deficits in the cerebellar locomotor region (CLR) have been associated with loss of gait automaticity in individuals with freezing of gait in Parkinson's disease (freezers); however, exercise interventions that restore gait automaticity in freezers are lacking. We evaluated the effects of the adapted resistance training with instability ([ARTI] complex exercises) compared with traditional motor rehabilitation (without complex exercises) on gait automaticity and attentional set-shifting. We also verified associations between gait automaticity change and CLR activation change previously published.

METHODS

Freezers were randomized either to the experimental group (ARTI, n = 17) or to the active control group (traditional motor rehabilitation, n = 15). Both training groups performed exercises 3 times a week for 12 weeks. Gait automaticity (dual-task and dual-task cost [DTC] on gait speed and stride length), single-task gait speed and stride length, attentional set-shifting (time between Trail Making Test parts B and A), and CLR activation during a functional magnetic resonance imaging protocol of simulated step initiation task were evaluated before and after interventions.

RESULTS

Both training groups improved gait parameters in single task (P < 0.05), but ARTI was more effective than traditional motor rehabilitation in improving DTC on gait speed, DTC on stride length, dual-task stride length, and CLR activation (P < 0.05). Changes in CLR activation were associated with changes in DTC on stride length (r = 0.68, P = 0.002) following ARTI. Only ARTI improved attentional set-shifting at posttraining (P < 0.05).

CONCLUSIONS

ARTI restores gait automaticity and improves attentional set-shifting in freezers attributed to the usage of exercises with high motor complexity. © 2020 International Parkinson and Movement Disorder Society.

Nocebo and lessebo effects

The power of placebos is commonly associated with the placebo effect. In contrast, detrimental effects related to the use of a placebo are little studied and less well recognized. This chapter covers the nocebo and lessebo effects defined, respectively, as expectation of harm in the form of adverse events in a placebo arm and reduction of therapeutic benefit due to the uncertainty of being allocated to placebo. The lessebo effect is a more recent concept and has been described only in depression, schizophrenia and Parkinson's disease. The nocebo response was evaluated in many neurological diseases, including epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, restless leg syndrome, among others. Meta-analyses of randomized controlled trials in these conditions reveal a significant variability of the magnitude of the nocebo response and that factors related to study design, study participants or neurological disease can be associated with a nocebo response, although with the opposing findings across conditions. The knowledge about neurobiological mechanisms of the nocebo effect is poor for neurological diseases, and most of the information has been generated in pain. Functional neuroimaging suggests the existence of a distinct network for the anticipation and the experience of a hyperalgesia nocebo response. Different types of neurotransmitters have been involved, including cholecystokinin, dopamine and opioids. Recognizing the potential impact of nocebo and lessebo effects, mitigating strategies are in development with application to clinical research and clinical practice, such as a contextualized informed consent process, alternative study designs and enhancement of patient-physician communication.

Clinical and pharmacokinetics equivalence of multiple doses of levodopa benserazide generic formulation vs the originator (Madopar)

AIMS

While several generic preparations of levodopa/carbidopa and levodopa/benserazide (LBD) are currently available, pharmacokinetic (PK) equivalence and therapeutic equivalence studies with levodopa generics are not available in Italy. Lack of data on generic formulations is a critical factor for their limited use in this country and often lead patients to refuse the generic version of the branded drug.

METHODS

An experimental, 2-centre, randomized, double-blind, 2-sequence, noninferiority cross-over study was designed to evaluate both the PK equivalence and clinical equivalence of multiple doses of the generic preparation of LDB, Teva Italia, compared to the originator (Madopar). Forty-three out-patients with a diagnosis of idiopathic Parkinson's disease on LDB, were recruited and randomly assigned to 1 of 2 study sequences: generic-originator or originator-generic. Clinical evaluations were performed at the end of each study period. A PK study with an LDB fixed dose (100 + 25 mg) was performed in a subpopulation of 14 subjects.

RESULTS

Clinical data showed a reduction of 0.49 and 1.54 in the mean UPDRS III scores for the LDB and the originator, respectively. The 95% CIs [-2.21: 0.11] of the mean difference original vs LDB are smaller than the clinically significant difference of 3 UPDRS III points, supporting the conclusion that the treatment with LDB is not inferior to the originator. No statistically significant differences were found with respect to area under the curve to last dose, half-life, maximum concentration, time to maximum concentration and last observed concentration.

CONCLUSION

These findings prove the therapeutic clinical equivalence as well the PK equivalence of the generic LDB and the originator (Madopar).

Nicotinic treatment of post-chemotherapy subjective cognitive impairment: a pilot study

PURPOSE

Persistent chemotherapy-related cognitive impairment (pCRCI) is commonly reported following cancer treatment and negatively affects quality of life; however, there is currently no pharmacological treatment indicated for pCRCI. This pilot study obtained preliminary data regarding the use of transdermal nicotine patches as a therapeutic strategy for women with pCRCI to (1) reduce subjective cognitive complaints and (2) enhance objective cognitive performance in breast, colon, lymphoma, or ovarian cancer survivors with pCRCI.

METHODS

Participants were randomized to either placebo (n = 11) or transdermal nicotine (n = 11) for 6 weeks, followed by 2 weeks of treatment withdrawal for a total of 8 weeks. Participants were assessed using both subjective and objective measures of cognitive functioning at five visits before, during, and after treatment.

RESULTS

Over the course of the study, women in both groups improved substantially in severity of self-reported cognitive complaints measured by Functional Assessment of Cancer Therapy-Cognitive Function Perceived Cognitive Impairments regardless of treatment arm. Additionally, objective cognitive performance measures improved in both groups; however, there was no significant difference in improvement between groups.

CONCLUSIONS

Due to a large placebo response, we were unable to determine if a drug effect was present. However, we did observe substantial improvement in self-reported cognitive symptoms, likely resulting from factors related to participation in the trial rather than specific drug treatment effects.

TRIAL REGISTRATION

The study was registered with clinicaltrials.gov (trial registration: NCT02312943).

IMPLICATIONS FOR CANCER SURVIVORS

These results suggest that women with pCRCI can exhibit improvement in subjective cognition, with attention paid to symptoms and close follow-up over a short period of time.

Neurobiology of placebo effect in Parkinson's disease: What we have learned and where we are going

The placebo effect is a phenomenon produced when an inert substance administered like a regular treatment improves the clinical outcome. Parkinson's disease (PD) is one of the main clinical disorders for which the placebo response rates are high. The first evidence of the neurobiological mechanisms underlying the placebo effect in PD stems from 2001, when de la Fuente-Fernandez and colleagues demonstrated that a placebo injection led to the release of dopamine in the striatal nuclei of PD measured with positron emission tomography technology. Since then, several studies have been conducted to investigate the neurobiological underpinnings of placebo responses. This article presents a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Of an initial yield of 143 papers, 19 were included. The lessons learned from these studies are threefold: (i) motor improvement is dependent on the activation of the entire nigrostriatal pathway induced by dopamine release in the dorsal striatum; (ii) the magnitude of placebo-induced effects is modulated by an expectancy of improvement, which is in turn related to the release of dopamine within the ventral striatum; (iii) the functioning of the neural pathways underlying the placebo response can be tuned by prior exposure and learning strategies. In conclusion, although the neural network underlying the placebo effect in PD has been largely confirmed and accepted, what remains to be established is how, when, and where the expectation of reward (mediated by the ventral striatum) interacts with the primary motor system (mediated by the dorsal striatum) to induce clinical improvement in motor symptoms. © 2018 International Parkinson and Movement Disorder Society.

Functional Movement Disorders and Placebo: A Brief Review of the Placebo Effect in Movement Disorders and Ethical Considerations for Placebo Therapy

Background

Functional movement disorders are common and disabling neurologic conditions. Patients with functional neurologic disorders represent a large proportion of neurology clinic referrals, and limited availability of subspecialty care creates a considerable burden for the healthcare system. These conditions are currently treated with a combination of physical therapy and cognitive behavioral therapy, with variable success.

Methods

We searched the Medline database for studies on the epidemiology and physiology of functional movement disorders, as well as those on the placebo effect in movement disorders. We reviewed and summarized the literature on these topics and explored ethical issues concerning the administration of placebos to patients with functional movement disorders.

Results

Studies of placebos, particularly in patients with movement disorders, have shown that these "inert" agents can provide demonstrable neurophysiologic benefits, even in open-label studies. Physician surveys have shown that many administer placebos for diagnostic and therapeutic purposes, although there are ethical concerns about this practice. We used a principle-based approach and reviewed ethical arguments for (justice and beneficence) and against (non-maleficence and autonomy) the use of placebos in functional movement disorders. In this context, we argue for the importance of the therapeutic alliance in preserving patient autonomy while exploring the potential benefits of placebo therapy.

Conclusions

An ethical argument is presented in support of nondeceptive clinical placebo use for the treatment of functional movement disorders. Patient and clinician attitudes regarding the use of placebos should be investigated before placebo-therapy trials are conducted.

Deep brain stimulation improves restless legs syndrome in patients with Parkinson disease

OBJECTIVE

To study the effect of subthalamic nucleus (STN) deep brain stimulation (DBS) in patients with Parkinson disease (PD) and moderate to severe restless legs syndrome (RLS) on their RLS symptoms.

METHODS

Patients undergoing STN DBS surgery for PD completed the International RLS Study Group Rating Scale (IRLS) and RLS Quality of Life (QoL) questionnaires preoperatively and postoperatively at 6 months, 1 year, and 2 years. The primary outcome measure was IRLS sum score and subscales (severity and impact) and the secondary measure was RLS QoL scores. Differences among the mean scores over time were analyzed using mixed model regression.

RESULTS

Twenty-two patients were enrolled. The preoperative IRLS sum scores were 19.59 ± 6.95, severity subscale 12.91 ± 4.33, impact subscale 4.45 ± 2.72, and transformed RLS QoL score 68.30 ± 20.26. The differences between preoperative and averaged postoperative scores were IRLS sum score -7.80, severity subscale -5.50, impact subscale -1.20, and RLS QoL 4.73. The overall F tests demonstrated differences among the times for the means of the IRLS sum and subscales: p < 0.05. There were no correlations between RLS symptoms improvement and PD motor symptoms improvement or reduction in PD medications. Half of the patients had at least 50% improvement and 27% had resolution of their RLS symptoms (IRLS = 0).

CONCLUSIONS

STN DBS significantly decreased RLS symptoms in patients with PD despite a decrease in dopaminergic treatment. This improvement was sustained over a 2-year period.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with PD and moderate to severe RLS, STN DBS improves RLS symptoms.

Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease

OBJECTIVE

To evaluate whether the progression of individual motor features was influenced by early deep brain stimulation (DBS), a post hoc analysis of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) score (after a 7-day washout) was conducted from the 2-year DBS in early Parkinson disease (PD) pilot trial dataset.

METHODS

The prospective pilot trial enrolled patients with PD aged 50-75 years, treated with PD medications for 6 months-4 years, and no history of dyskinesia or other motor fluctuations, who were randomized to receive optimal drug therapy (ODT) or DBS plus ODT (DBS + ODT). At baseline and 6, 12, 18, and 24 months, all patients stopped all PD therapy for 1 week (medication and stimulation, if applicable). UPDRS-III "off" item scores were compared between the ODT and DBS + ODT groups (n = 28); items with significant between-group differences were analyzed further.

RESULTS

UPDRS-III "off" rest tremor score change from baseline to 24 months was worse in patients receiving ODT vs DBS + ODT (p = 0.002). Rest tremor slopes from baseline to 24 months favored DBS + ODT both "off" and "on" therapy (p < 0.001, p = 0.003, respectively). More ODT patients developed new rest tremor in previously unaffected limbs than those receiving DBS + ODT (p = 0.001).

CONCLUSIONS

These results suggest the possibility that DBS in early PD may slow rest tremor progression. Future investigation in a larger cohort is needed, and these findings will be tested in the Food and Drug Administration-approved, phase III, pivotal, multicenter clinical trial evaluating DBS in early PD.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with early PD, DBS may slow the progression of rest tremor.

Feasibility of a randomized single-blind crossover trial to assess the effects of the second-generation slow-release dopamine agonists pramipexole and ropinirole on cued recall memory in idiopathic mild or moderate Parkinson's disease without cognitive impairment

Background

The aim was to assess the feasibility of a single-centre, single-blind, randomized, crossover design to explore the effects of two slow-release dopamine agonists, ropinirole and pramipexole, on cued recall in Parkinson’s disease.

As the design required a switch from the prescribed agonist (pramipexole-to-ropinirole, or ropinirole-to-pramipexole), the primary objectives were to (a) examine the efficacy of processes and procedures used to manage symptoms during the washout period and (b) to use cued recall estimates to inform a power calculation for a definitive trial.

Secondary objectives were to assess consent and missing data rates, acceptability of clinical support for the OFF sessions, experience of the OFF sessions and of agonist switching, barriers-to-participation for patients and informal caregivers.

Methods

Patients were randomized in a 1:1 ratio to two treatment arms and stabilized on each agonist for 6 weeks. The arms differed only in the sequence in which the agonists were administered. Cued recall was assessed ON medication and, following a washout period resulting in 93.75% agonist elimination, OFF medication.

Results

A total of 220 patients were screened: 145 were excluded and 75 invitations to participate were sent to eligible patients. Fifty-three patients declined, 22 consented and 16 completed the study.

There were no serious adverse events, and rates of non-serious adverse events were equivalent between the agonists.

Using the largest standard deviation (SD) of the ON–OFF difference cued recall score (inflated by ~25% to give a conservative estimate of the SD in a definitive trial) and assuming an effect of at least 10% of the observed range of OFF medication cued recall scores for either agonist to be clinically important, a main trial requires a sample size of just under 150 patients.

The consent and missing data rates were 29 and 27% respectively. The washout period and the preparation for the OFF sessions were acceptable, and the sessions were manageable. The experience of switching was also manageable. Barriers to participation included concerns about disease stability, side effects, research process, carer workload and accessibility of the information sheet.

Conclusions

This study presented challenges to recruitment both in design and execution, and while it was a major aim of the study to assess this, evaluation of these challenges provided the opportunity to explore how they could be overcome for future studies.

Trial registration

EudraCT 2012-000801-64

Probiotics Ingestion Does Not Directly Affect Thyroid Hormonal Parameters in Hypothyroid Patients on Levothyroxine Treatment

PURPOSE

The relationship between probiotics and levothyroxine (LT₄) requirement has not yet been investigated. The aim of this study was to assess whether a mixture of highly charged Lactobacilli and Bifidobacteria (VSL#3^®) is able to influence LT₄ metabolism acting on the gut microbiota.

METHODS

A prospective, randomized, single-blind, controlled, investigator-started clinical trial was carried out. Patients with primary hypothyroidism were randomly assigned to the study (VSL#3^® + LT₄) and the control group (LT₄). A 2-month treatment phase was followed by 2 months of follow-up. Clinical examination, blood tests for thyroid function and for peripheral tissue markers of thyroid hormones (PTM) were performed monthly. LT₄ dose adjustments were performed when necessary.

RESULTS

Thirty-nine patients were enrolled in the study group and 41 in the control group. No difference in thyroid function [thyroid-stimulating hormone (TSH), free triiodothyronine (fT₃), and free thyroxine (fT₄)] and PTM was found between groups and among visits. FT₃/fT₄ ratio was directly correlated to TSH at each visit in both groups, with the exception of the first evaluation of probiotics-treated subjects (rho = 0.287, p = 0.076). LT₄ daily dose adjustments occurred more frequently in the control than in the study group (p = 0.007), despite no differences in the mean LT₄ daily dose. In particular, LT₄ doses were increased six times in the control group and decreased four times in the study group.

CONCLUSION

VSL#3^® does not directly alter thyroid functional compensation. A probiotics-mediated influence on thyroid hormones homeostasis is suggested since probiotics supplementation could be able to prevent serum hormonal fluctuations.

CLINICALTRIALSGOV ID

Registration number NCT03095963.

Factors influencing the outcome of deep brain stimulation: Placebo, nocebo, lessebo, and lesion effects

Deep brain stimulation (DBS) is a well-established treatment option for movement disorders, especially for Parkinson's disease (PD). There is a need to determine the role of expectation of benefit and the use of placebo to better understand the effects of electrode placement including the (micro)lesion effect. These factors must be understood to better interpret and attribute the therapeutic value of DBS. In this review, we critically present currently available data on the placebo, nocebo, lessebo, and lesion effects in the context of DBS. We provide a discussion of strategies that have the potential for controlling these effects in the setting of future DBS trials. We conclude that there is a need to standardize definitions for nocebo and (micro)lesion effects and that there are intrinsic limitations in defining the effect of expectation of benefit in DBS. These issues will be challenging to overcome especially with current technology and available study designs. New stimulation paradigms, better study designs, and the use of adaptive closed-loop DBS devices may facilitate a more accurate assessment of the placebo, nocebo, and lessebo effects in future DBS trials.

Dopamine D2 receptor gene variants and response to rasagiline in early Parkinson's disease: a pharmacogenetic study

The treatment of early Parkinson's disease with dopaminergic agents remains the mainstay of symptomatic therapy for this incurable neurodegenerative disorder. However, clinical responses to dopaminergic drugs vary substantially from person to person due to individual-, drug- and disease-related factors that may in part be genetically determined. Using clinical data and DNA samples ascertained through the largest placebo-controlled clinical trial of the monoamine oxidase B inhibitor, rasagiline (ClinicalTrials.gov number, NCT00256204), we examined how polymorphisms in candidate genes associate with the clinical response to rasagiline in early Parkinson's disease. Variants in genes that express proteins involved in the pharmacokinetics and pharmacodynamics of rasagiline, and genes previously associated with the risk to develop Parkinson's disease were genotyped. The LifeTechnologies OpenArray NT genotyping platform and polymerase chain reaction-based methods were used to analyse 204 single nucleotide polymorphisms and five variable number tandem repeats from 30 candidate genes in 692 available DNA samples from this clinical trial. The peak symptomatic response to rasagiline, the rate of symptom progression, and their relation to genetic variation were examined controlling for placebo effects using general linear and mixed effects models, respectively. Single nucleotide polymorphisms, rs2283265 and rs1076560, in the dopamine D2 receptor gene (DRD2) were found to be significantly associated with a favourable peak response to rasagiline at 12 weeks in early Parkinson's disease after controlling for multiple testing. From a linear regression, the betas were 2.5 and 2.38, respectively, with false discovery rate-corrected P-values of 0.032. These polymorphisms were in high linkage disequilibrium with each other (r(2) = 0.96) meaning that the same clinical response signal was identified by each of them. No polymorphisms were associated with slowing the rate of worsening in Parkinson symptoms from Weeks 12 to 36 after correction for multiple testing. This is the largest and most comprehensive pharmacogenetics study to date examining clinical response to an anti-parkinsonian drug and the first to be conducted in patients with early stage Parkinson's disease receiving monotherapy. The results indicate a clinically meaningful benefit to rasagiline in terms of the magnitude of improvement in parkinsonian symptoms for those with the favourable response genotypes. Future work is needed to elucidate the specific mechanisms through which these DRD2 variants operate in modulating the function of the nigrostriatal dopaminergic system.media-1vid110.1093/brain/aww109_video_abstractaww109_video_abstract.

Association Between Placebo-Activated Neural Systems and Antidepressant Responses: Neurochemistry of Placebo Effects in Major Depression

IMPORTANCE

High placebo responses have been observed across a wide range of pathologies, severely impacting drug development.

OBJECTIVE

To examine neurochemical mechanisms underlying the formation of placebo effects in patients with major depressive disorder (MDD).

DESIGN, SETTING, AND PARTICIPANTS

In this study involving 2 placebo lead-in phases followed by an open antidepressant administration, we performed a single-blinded 2-week crossover randomized clinical trial of 2 identical oral placebos (described as having either active or inactive fast-acting antidepressant-like effects) followed by a 10-week open-label treatment with a selective serotonin reuptake inhibitor or, in some cases, another agent as clinically indicated. The volunteers (35 medication-free patients with MDD at a university health system) were studied with positron emission tomography and the µ-opioid receptor-selective radiotracer [11C]carfentanil after each 1-week inactive and active oral placebo treatment. In addition, 1 mL of isotonic saline was administered intravenously within sight of the volunteer during positron emission tomographic scanning every 4 minutes over 20 minutes only after the 1-week active placebo treatment, with instructions that the compound may be associated with the activation of brain systems involved in mood improvement. This challenge stimulus was used to test the individual capacity to acutely activate endogenous opioid neurotransmision under expectations of antidepressant effect.

MAIN OUTCOMES AND MEASURES

Changes in depressive symptoms in response to active placebo and antidepressant. Baseline and activation measures of µ-opioid receptor binding.

RESULTS

Higher baseline µ-opioid receptor binding in the nucleus accumbens was associated with better response to antidepressant treatment (r = 0.48; P = .02). Reductions in depressive symptoms after 1 week of active placebo treatment, compared with the inactive, were associated with increased placebo-induced µ-opioid neurotransmission in a network of regions implicated in emotion, stress regulation, and the pathophysiology of MDD, namely, the subgenual anterior cingulate cortex, nucleus accumbens, midline thalamus, and amygdala (nucleus accumbens: r = 0.6; P < .001). Placebo-induced endogenous opioid release in these regions was associated with better antidepressant treatment response, predicting 43% of the variance in symptom improvement at the end of the antidepressant trial.

CONCLUSIONS AND RELEVANCE

These data demonstrate that placebo-induced activation of the µ-opioid system is implicated in the formation of placebo antidepressant effects in patients with MDD and also participate in antidepressant responses, conferring illness resiliency, during open administration.

TRIAL REGISTRATION

clinicaltrials.gov Identifier:NCT02178696.

Recruitment strategies and patient selection in clinical trials for Parkinson's disease: Going viral and keeping science and ethics at the highest standards

INTRODUCTION

Enrollment of an adequate number of suitable candidates is a critical component of good quality randomized controlled trials (RCTs). Parkinson's disease (PD) is a highly heterogeneous disease and recruiting a large and homogeneous sample of patients is often challenging. Further, PD patients are often elderly, cognitively impaired and disabled, thus requiring the assistance from their caregivers for participation in RCTs. Only a limited number of studies have explored the effectiveness of recruitment strategies and PD patient selection in clinical trials. We aim to review the four crucial recruitment components of RCTs (i.e. infrastructure, nature of the research, recruiter characteristics and participant characteristics) with particular implications in PD, and to explore strategies to improve recruitment and patient selection in RCTs in PD.

CONCLUSION

Movement disorders centers have a key role in managing recruitment and patient selection in RCTs in PD. Key recommendations within the infrastructure component are to improve trust and communication between patient and participant, and to consider the diversity, perceived disadvantages, and health care accessibility of the participants. Further, study designs that involve participant's opinions and considers placebo and lessebo effects are highly recommended for the nature of the research component of RCTs. Finally, a team-based approach with recruiters and participants that establishes relationships between researchers and the community and addresses ethical considerations are encouraged as part of the recruiters and participants components. Finally, we envisage a greater usage of internet-based strategies for clinical trials recruitment in PD with the goal of 'going viral' with the recruitment.

Proceedings of the Second Annual Deep Brain Stimulation Think Tank: What's in the Pipeline

The proceedings of the 2nd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, and computational work on DBS for the treatment of neurological and neuropsychiatric disease and represent the insights of a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers and members of industry. Presentations and discussions covered a broad range of topics, including advocacy for DBS, improving clinical outcomes, innovations in computational models of DBS, understanding of the neurophysiology of Parkinson's disease (PD) and Tourette syndrome (TS) and evolving sensor and device technologies.

Impact of 6-month earlier versus postponed initiation of rotigotine on long-term outcome: post hoc analysis of patients with early Parkinson's disease with mild symptom severity

OBJECTIVE

Investigate impact of 6-month earlier versus postponed initiation of rotigotine in patients with early Parkinson's disease (PD) with mild symptom severity.

BACKGROUND

Long-term benefit of rotigotine in early-PD has been demonstrated: SP702 (NCT00594165) and SP716 (NCT00599196) were long-term, open-label extensions of double-blind, placebo-controlled studies of 6-month maintenance; rotigotine was well tolerated for up to 6 years, and demonstrated efficacy (Unified Parkinson's Disease Rating Scale [UPDRS] II + III below baseline) for ∼ 2 years (SP702) and ∼ 4 years (SP716).

METHODS

Post hoc analysis of patients at Hoehn and Yahr 1-2; groups defined by treatment received in 6-month double-blind studies: 'Rotigotine-Rotigotine' received rotigotine (n = 221), 'Placebo-Rotigotine' received placebo (n = 125).

RESULTS

At the start of open-label rotigotine maintenance, UPDRS II + III mean ± SD change from double-blind baseline was: -8.5 ± 10.6 'Rotigotine-Rotigotine', -7.7 ± 9.0 'Placebo-Rotigotine.' After this initial improvement scores gradually increased: It took ∼ 45 months for mean scores to cross baseline in 'Rotigotine-Rotigotine', and ∼ 21 months in 'Placebo-Rotigotine.' At the time mean UPDRS II + III had crossed baseline in 'Placebo-Rotigotine' (open-label week 84; ∼ 21 months), treatment difference (LS-mean) to 'Rotigotine-Rotigotine' change from baseline was -3.89 (95% CI -6.94, -0.84); p = 0.013.

CONCLUSIONS

In this post hoc analysis, 6-month earlier initiation of rotigotine resulted in slower return to baseline mean UPDRS II + III; initiation of rotigotine in patients with minimal/no functional disability or impairment may lead to an extended benefit.