Cognition and freezing of gait in Parkinson's disease: A systematic review and meta-analysis

Freezing of gait (FOG) is a common and disabling symptom in people with Parkinson's Disease (PwPD). Although cognition is thought to be worse in PwPD who freeze, a comprehensive analysis of this relationship will inform future research and clinical care. This systematic review and meta-analysis compared cognition between PwPD who do and do not exhibit FOG across a range of cognitive domains and assessed the impact of disease severity and medication status on this relationship. 145 papers (n = 9010 participants) were included in the analysis, with 144 and 138 articles meeting the criteria to assess moderating effects of disease severity and medication status, respectively. PwPD who freeze exhibited worse cognition than PwPD without FOG across global cognition, executive function/attention, language, memory, and visuospatial domains. Greater disease severity and "ON" levodopa medication status moderated the FOG status-cognition relationship in global cognitive performance but not in other cognitive domains. This meta-analysis confirmed that cognition is worse in PwPD with FOG and highlights the importance of disease severity and medication status in this relationship.

Comparative analysis of freezing of gait in distinct Parkinsonism types by diffusion tensor imaging method and cognitive profiles

Freezing of gait (FOG) is an episodic gait pattern that is common in advanced Parkinson's disease (PD) and other atypical parkinsonism syndromes. Recently, disturbances in the pedunculopontine nucleus (PPN) and its connections have been suggested to play a critical role in the development of FOG. In this study, we aimed to demonstrate possible disturbances in PPN and its connections by performing the diffusion tensor imaging (DTI) technique. We included 18 patients of PD with FOG [PD-FOG], 13 patients of PD without FOG [PD-nFOG] and 12 healthy subjects as well as a group of patients with progressive supranuclear palsy (PSP), an atypical parkinsonism syndrome which is very often complicated with FOG [6 PSP-FOG, 5 PSP-nFOG]. To determine the specific cognitive parameters that can be related to FOG, deliberate neurophysiological evaluations of all the individuals were performed. The comparative analyses and correlation analyses were performed to reveal the neurophysiological and DTI correlates of FOG in either group. We have found disturbances in values reflecting microstructural integrity of the bilateral superior frontal gyrus (SFG), bilateral fastigial nucleus (FN), left pre-supplementary motor area (SMA) in the PD-FOG group relative to the PD-nFOG group. The analysis of the PSP group also demonstrated disturbance in left pre-SMA values in the PSP-FOG group likewise, while negative correlations were determined between right STN, left PPN values and FOG scores. In neurophysiological assessments, lower performances for visuospatial functions were demonstrated in FOG ( +) individuals for either patient group. The disturbances in the visuospatial abilities may be a critical step for the occurrence of FOG. Together with the results of DTI analyses, it might be suggested that impairment in the connectivity of disturbed frontal areas with disordered basal ganglia, maybe the key factor for the occurrence of FOG in the PD group, whereas left PPN which is a nondopaminergic nucleus may play a more prominent role in the process of FOG in PSP. Moreover, our results support the relationship between right STN, and FOG as mentioned before, as well as introduce the importance of FN as a new structure that may be involved in FOG pathogenesis.

Long-term independence and quality of life after subthalamic stimulation in Parkinson's disease

Background and purpose

Studies on long‐term nonmotor outcomes of subthalamic nucleus stimulation in Parkinson disease (PD) are scarce. This study reports on very long‐term non‐motor and motor outcomes in one of the largest cohorts of people with advanced PD, treated for >10 years with subthalamic nucleus stimulation. The main outcome was to document the evolution of independence in activities of daily living. The secondary outcomes were to measure the change in quality of life, as well as non‐motor and motor outcomes.

Methods

Patients were studied preoperatively, at 1 year, and beyond 10 years after subthalamic stimulation with an established protocol including motor, non‐motor, and neuropsychological assessments.

Results

Eighty‐five people with PD were included. Independence scores in the off‐medication condition (measured with the Schwab & England Activities of Daily Living Scale) as well as quality of life (measured with the Parkinson's Disease Questionnaire [PDQ]‐37) remained improved at longest follow‐up compared to preoperatively (respectively, p < 0.001, p = 0.015). Cognitive scores, measured with the Mattis Dementia Rating Scale, significantly worsened compared to before and 1 year after surgery (p < 0.001), without significant change in depression, measured with the Beck Depression Inventory. Motor fluctuations, dyskinesias, and off dystonia remained improved at longest follow‐up (p < 0.001), with a significant reduction in dopaminergic treatment (45%, p < 0.001).

Conclusions

This study highlights the long‐term improvement of subthalamic stimulation on independence and quality of life, despite the progression of disease and the occurrence of levodopa‐resistant symptoms.

Levodopa ONOFF-state freezing of gait: Defining the gait and non-motor phenotype

Background

Freezing in the levodopa-medicated-state (ON-state) is a debilitating feature of Parkinson’s disease without treatment options. Studies detailing the distinguishing features between people with freezing of gait that improves with levodopa and those whose freezing continues even on levodopa are lacking.

Objective

To characterize the gross motor, gait, and non-motor features of this phenotype.

Methods

Instrumented continuous gait was collected in the levodopa-medicated-state in 105 patients: 43 non-freezers (no-FOG), 36 with freezing only OFF-levodopa (OFF-FOG) and 26 with freezing both ON- and OFF-levodopa (ONOFF-FOG). Evaluation of motor and non-motor disease features was undertaken using validated scales. A linear mixed model with age, sex, disease duration, and motor UPDRS scores as covariates was used to determine differences in spatiotemporal gait and non-motor disease features among the groups.

Results

Compared to OFF-FOG, the ONOFF-FOG group had greater disease severity (on the Unified Parkinson’s disease Rating Scale) and worse cognition (on the Montreal Cognitive Assessment, Frontal Assessment Battery and Scales for Outcome in Parkinson’s disease-Cognition scales) and quality of life (on the PDQ-39), but similar mood (on the Hamilton depression and anxiety scales) and sleep quality (on Epworth sleepiness scale and RBD questionnaire). For several gait features, differences between the ONOFF-OFF groups were at least as large and in the opposite direction as differences between OFF-no groups, controlling for disease severity. Variability in ONOFF-FOG was greater than in other groups. Using results from our study and others, a power analysis for a potential future study reveals sample sizes of at least 80 ONOFF and 80 OFF-FOG patients would be needed to detect clinically meaningful differences.

Conclusions

Intra-patient variability in spatiotemporal gait features was much greater in ONOFF-FOG than in the other two groups. Our results suggest that multifactorial deficits may lead to ONOFF-FOG development.

Levodopa-Carbidopa Intestinal Gel may improve treatment-resistant freezing of gait in Parkinson’s disease

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Freezing of gait (FOG) in Parkinson’s Disease (PD) is difficult to control with oral levodopa.

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Levodopa-Carbidopa Intestinal Gel (LCIG) may be a therapeutic option for patients with FOG.

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This review examines the current literature on LCIG as a therapy for FOG.

Introduction

Freezing of gait (FOG) is a highly disabling symptom in Parkinson’s Disease (PD) with varying degree of benefits from oral dopaminergic medications and several subtypes that present with different medication states (e.g., off FOG, on FOG, pseudo-on FOG, supra-on FOG). Levodopa-Carbidopa Intestinal Gel (LCIG) greately reduces the variability of cerebral dopamine replacement inherent to oral therapies by continuous levodopa intestinal infusion. While LCIG may be superior to oral therapy in its ability to treat motor fluctuations and minimize off-time, there is no consensus regarding the overall effectiveness of LCIG specifically for the treatment of FOG in PD patients.

Methods

A systematic literature review was conducted to understand the efficacy of LCIG to treat FOG in PD patients. A PubMed search was conducted using the search query “Intestinal AND (Levodopa OR L-dopa) AND Freezing of Gait AND Parkinson.” Additional eligibility criteria included articles written in English and currently published journal articles. Articles were excluded if they did not have a clinical design or if they did not yield reportable data on FOG.

Results

The literature search yielded 16 articles, of which 10 articles were included. Of the 10 studies included, there were 3 retrospective studies, 6 case reports or case series, and 1 open-label study. (n = 449 patients total and 318 FOG patients). Nine of the 10 studies concluded that LCIG has a favorable effect on FOG, though the metrics to evaluate benefits of LCIG on FOG varied among the articles.

Conclusion

LCIG may be an effective treatment for PD patients suffering from FOG including those with poor response to oral medication, likely because of its ability to maintain steadier dopamine levels. Further research is necessary on LCIG as a therapy for refractory FOG, with particular attention to the different subtypes of FOG.

Freezing of Gait can persist after an acute levodopa challenge in Parkinson's disease

Study objectives included testing whether presumed levodopa-unresponsive freezing of gait (FOG) in Parkinson's disease (PD) actually persists in the presence of adequate dopaminergic dosing and to investigate whether the presence of other parkinsonian features and their responsiveness to therapy varies across patients without FOG (NO-FOG), with levodopa-responsive FOG (OFF-FOG), and with levodopa-unresponsive FOG (ONOFF-FOG). Fifty-five PD patients completed levodopa challenges after >12-h OFF with supratherapeutic doses of dopaminergic medications. Observed responses in FOG, measured with MDS-UPDRS-III during the patient reported full "ON", were used to classify them as NO-FOG, OFF-FOG, or ONOFF-FOG. Serum levodopa levels were measured. Only those with ≥20% improvement in MDS-UPDRS-III score were included in analyses. Levodopa challenge was sufficient to bring about a full "ON" state with ≥20% improvement in 45 patients. Levodopa-equivalent-dose utilized was 142 ± 56% of patients' typical morning doses. Overall, 19/45 patients exhibited FOG in the full "ON" state (ONOFF-FOG), 11 were classified as OFF-FOG, and 15 NO-FOG. Linear mixed models revealed a highly significant association between serum levodopa level and total MDS-UPDRS-III score that was similar across groups. The ONOFF-FOG group exhibited significantly higher New-FOG-questionnaire and MDS-UPDRS-II scores compared to the OFF-FOG group. Among MDS-UPDRS-III subdomains significant effects of group (highest in ONOFF-FOG) were identified for other axial parkinsonian features. We found that FOG can persist in the full "ON" state brought about by ample dopaminergic dosing in PD. Other axial measures can also be levodopa-unresponsive among those with ONOFF-FOG only. These data provide evidence that ONOFF-FOG is distinct from responsive freezing.

Clinical and anatomical predictors for freezing of gait and falls after subthalamic deep brain stimulation in Parkinson's disease patients

INTRODUCTION

Freezing of gait (FOG) and falls are the most disabling motor symptoms in Parkinson's disease (PD) patients. The effects of subthalamic deep-brain-stimulation (STN-DBS) on FOG and falls are still a matter of controversy, and factors contributing to their outcome have yet to be defined.

METHODS

We examined the relationship between FOG and falls after STN-DBS and preoperative clinical features, MRI voxel-based-morphometry (VBM) analysis and statistical mapping of electrode locations.

RESULTS

331 patients (age at surgery = 57.7 ± 8.4 years; disease duration = 12.5 ± 5 years) were included in the final analysis, with VBM analysis in 151 patients. After surgery, FOG was aggravated in 93 patients and falls in 75 patients. After surgery, FOG severity was related to its level before surgery without dopaminergic treatment, the dopaminergic treatment dosage and severity of motor fluctuations after surgery; and falls severity to lower postoperative cognitive performance. VBM analyses revealed that, relative to other patient groups, patients with FOG worsening had putamen grey matter density decrease, and fallers patients a left postcentral gyrus atrophy. The best effects of STN-DBS on FOG and falls were associated with the location of contacts within the STN, but no specific location related to aggravation.

CONCLUSIONS

FOG and falls are reduced after STN-DBS in about 1/3 of patients, with the best effects obtained for electrodes located within the STN. Clinicians should be aware that, after STN-DBS, FOG severity is related to preoperative FOG severity whatever its dopa-sensitivity; and falls to lower postoperative cognitive performance; and atrophy of cortico-subcortical brain areas.

Managing Gait, Balance, and Posture in Parkinson's Disease

PURPOSE OF REVIEW

Postural instability and gait difficulties inexorably worsen with Parkinson's disease (PD) progression and become treatment resistant, with a severe impact on autonomy and quality of life. We review the main characteristics of balance instability, gait disabilities, and static postural alterations in advanced PD, and the available treatment strategies.

RECENT FINDINGS

It remains very difficult to satisfactorily alleviate gait and postural disturbances in advanced PD. Medical and surgical interventions often fail to provide satisfactory or durable alleviation of these axial symptoms, that may actually call for differential treatments. Exercise and adapted physical activity programs can contribute to improving the patients' condition. Gait, balance, and postural disabilities are often lumped together under the Postural Instability and Gait Difficulties umbrella term. This may lead to sub-optimal patients' management as data suggest that postural, balance, and gait problems might depend on distinct underlying mechanisms. We advocate for a multidisciplinary approach from the day of diagnosis.

Accelerometer based analysis of gait initiation failure in advanced juvenile parkinsonism: a single subject study

[Purpose] This study used an accelerometer placed close to the center of gravity to quantitatively investigate whether unexpected gait initiation aggravates start hesitation (freezing of gait in gait initiation). [Subject and Methods] The subject was a 53-year-old female who had been suffering from juvenile parkinsonism since she was aged 21 years. An alternating-treatment design was used to compare acceleration characteristics under two gait initiation conditions, which were 1) deliberate gait initiation and 2) gait initiation on a sudden “go” verbal command (sudden gait initiation), in the “on” state of the medication cycle. [Results] In six out of eight sessions, a combination of reduced peak positive anterior accelerations and large power percentage in the high frequency band was consistently observed in the sudden gait initiation compared with deliberate gait initiation. In the other two sessions, although a large acceleration just after the “go” signal was observed, subsequent acceleration signals were blocked by sudden gait initiation. [Conclusion] The results suggest that, even in the “on” state, start hesitation is apparent without increased reliance on frontal cortical attentional mechanisms to compensate for impaired automaticity. In advanced juvenile parkinsonism, sudden gait initiation may be an effective paradigm as a provoking test for start hesitation.

Freezing of Gait and its Associations in the Early and Advanced Clinical Motor Stages of Parkinson's Disease: A Cross-Sectional Study

BACKGROUND

Freezing of gait is a common disabling symptom of Parkinson's disease (PD) with limited treatment options. The pathophysiological mechanisms of freezing behaviour are still contentious.

OBJECTIVE

To investigate the prevalence of freezing of gait and its associations with increasing disease severity to gain a better understanding of the underlying pathophysiology.

METHODS

This exploratory study included 389 idiopathic PD patients, divided into four groups; early and advanced PD with freezing of gait, and early and advanced PD without freezing of gait. Motor, cognitive and affective symptoms, REM sleep behaviour disorder and autonomic function were assessed.

RESULTS

Regardless of disease stage, patients with freezing of gait had more severe motor symptoms and a predominant non-tremor phenotype. In the early stages, freezers had a selective impairment in executive function and had more marked REM sleep behaviour disorder. Autonomic disturbances were not associated with freezing of gait across early or advanced disease stages.

CONCLUSION

These findings support the notion that impairments across the frontostriatal pathways are intricately linked to the pathophysiology underlying freezing of gait across all stages of PD. Features of REM sleep behaviour disorder suggest a contribution to freezing from brainstem pathology but this does not extend to more general autonomic dysfunction.

Freezing of gait subtypes have different cognitive correlates in Parkinson's disease

BACKGROUND

Freezing of gait (FOG) is a major concern for Parkinson's disease (PD) patients because it is a leading cause of falls and is associated with poor quality of life. The pathophysiology is unknown but it is hypothesized that it relates to cognitive abnormalities; particularly executive and visuospatial dysfunction. However, prior results have been discrepant. Pharmacologic subtypes of FOG include those that are responsive and unresponsive to levodopa.

OBJECTIVE

To determine whether executive and visuospatial dysfunction are associated specifically with the levodopa unresponsive subtype of FOG.

METHODS

135 PD subjects completed a single assessment included FOG questionnaire, UPDRS motor scale, comprehensive cognitive battery and measure of hallucinations. Analyses compared unresponsive (n = 16), responsive (n = 20) and no FOG (n = 99) subtypes.

RESULTS

The unresponsive subtype had a significantly older age of onset of PD than the responsive group (p = .03) and had worse motor scores (p = .003) than the no FOG group. Longer disease duration was associated with the responsive group compared to the no FOG group (p = .002). The unresponsive FOG group had significantly poorer visuospatial ability (p = .001) and executive functioning (p = .02) than both the no and responsive FOG subgroups. These latter groups were not significantly different. The responsive FOG group was associated with the presence of hallucinations.

CONCLUSION

Aside from pharmacological differences, unresponsive FOG is associated with executive and visuospatial dysfunction implicating frontostriatal pathways while responsive FOG is associated with hallucinations suggesting involvement of posterior cortical regions. Further study and treatment of FOG should include appropriate subtype classification.

Relation between freezing of gait and frontal function in Parkinson's disease

INTRODUCTION

Freezing of gait (FOG) is a common symptom of Parkinson's disease (PD). Although the pathophysiological mechanism of FOG is unknown, previous studies have suggested that frontal dysfunction is associated with FOG. The Behavioral Assessment of the Dysexecutive Syndrome (BADS) battery, which is wide-ranging neurological battery composed of six subtests, evaluates frontal function and is more sensitive to executive dysfunction (ED) than other tools in PD patients. This is the first study to assess the relation between FOG in the 'on' state and frontal dysfunction evaluated using BADS.

METHODS

Subjects were 65 patients with PD. Multiple logistic regression analysis was used to compare the age-controlled standardized BADS score, age, disease duration, Hoehn and Yahr (HY) stage, levodopa-equivalent daily dose, and Mini-Mental State Examination (MMSE) score across patients with FOG (n = 43) and patients without FOG (n = 22). Score on each of the six BADS subtests were compared across patients with and without FOG using the Mann-Whitney U test.

RESULTS

Multiple logistic regression analysis revealed that FOG was related to lower age-controlled standardized BADS score (P = 0.022) and higher HY stage (P = 0.009) but not to disease duration, levodopa equivalent daily dose, or MMSE score. Among the six BADS subtests, score on the Zoo Map Test, which evaluates problem solving and planning, was lower in patients with FOG than in patients without FOG.

CONCLUSION

These results support a relation between on-state FOG and frontal dysfunction in PD patients.

Early phenotypic differences between Parkinson's disease patients with and without freezing of gait

BACKGROUND

Previous studies have associated freezing of gait in Parkinson's disease with the presence of specific phenotypic features such as mood disturbances, REM sleep behavior disorder and selective cognitive impairments. However, it is not clear whether these features are present in the earlier stages of disease or simply represent a more general pattern of progression. To investigate this issue, the current study evaluated motor, cognitive, affective and autonomic features as well as REM sleep behavior disorder in Parkinson's disease patients in the early stages of the condition.

METHODS

Thirty-eight freezers and fifty-three non-freezers with disease duration of less than five years and a Hoehn and Yahr stage of less than three were included in this study. The groups were matched on a number of key disease features including age, disease duration, motor severity and dopamine dose equivalence. Furthermore, patients were assessed on measures of motor, cognitive, affective and autonomic features, as well as REM sleep behavior disorder.

RESULTS

Compared to non-freezers, patients with freezing of gait had significantly more non-tremor symptoms and a selective impairment on executive functions, such as set-shifting ability and working memory. Freezers and non-freezers did not differ on measures of tremor, autonomic function, REM sleep behavior disorder, mood or more general cognition.

CONCLUSION

These results suggest the pathophysiological mechanisms underlying freezing of gait in the early clinical stages of Parkinson's disease are likely to be related to specific changes in the frontostriatal pathways rather than being due to brainstem or more diffuse neuropathology.