Authors: Marianna Amboni MD, PhD, Paolo Barone MD, PhD, Luigi Iuppariello MS, Ilaria Lista PhD, Riccardo Tranfaglia PhD, Alfonso Fasano MD, PhD, Marina Picillo MD, Carmine Vitale MD, PhD, Gabriella Santangelo PhD, Valeria Agosti PhD, Alessandro Iavarone MD, PhD, Giuseppe Sorrentino MD, PhD
Article first published online: 2 OCT 2012
Volume 27, Issue 12, October 2012, pages 1536-1543
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Although in recent years the relationship between cognition and gait in Parkinson's disease (PD) has received increasing attention, the specific connections between gait patterns and cognitive features are not fully understood. The objective of this study was to describe the gait patterns in patients affected by PD with or without mild cognitive impairment (MCI+ and MCI−, respectively). We also sought to find an association between gait patterns and specific cognitive profiles. Using a gait analysis system, we compared the gait patterns among MCI+ patients (n = 19), MCI− patients (n − 24), and age- and sex-matched healthy subjects (HS; n = 20) under the following conditions: (1) normal gait, (2) motor dual task, and (3) cognitive dual task. In PD patients, gait parameters were evaluated in both the off and on states. Memory, executive, and visuospatial domains were assessed using an extensive neuropsychological battery. Compared with MCI− PD and HS, MCI+ PD patients displayed reduced step length and swing time and impairment of measures of dynamic stability; these dysfunctions were only partially reversed by levodopa. We also found that dual-task conditions affected several walking parameters in MCI+ PD in the off and on states relative to MCI− PD and HS. Factor analysis revealed 2 independent factors, namely, pace and stability. The latter was strongly and directly correlated to the visuospatial domain. In conclusion, dysfunctions on specific gait parameters, which were poorly responsive to levodopa and highly sensitive to dual-task conditions, were associated with MCI in PD patients. Importantly, visuospatial impairment was strongly associated with the development of instability and more generally with the progression of PD.
© 2012 Movement Disorder Society
Summary and review by Dr. John Morgan, Associate Professor in the Movement Disorders Program, Department of Neurology, Georgia Health Sciences University, Augusta, GA, USA
The Editors' Choice article for December 2012/January 2013 is "Gait Patterns in Parkinsonian Patients With or Without Mild Cognitive Impairment," by Marianna Amboni and others from Naples, Italy. In this article, the authors' objective was to describe gait patterns in individuals with Parkinson's disease (PD) with and without mild cognitive impairment (MCI) and compare these patterns to age- and gender-matched healthy subjects. The authors found significant differences in gait parameters between PD subjects with and without MCI which I will review and discuss.
It is well known that, as PD progresses, gait impairment and cognitive impairment are common and often coexist in the same patient. This is most evident in those with PD who have a postural instability gait disorder (PIGD) phenotype relative to those with a benign tremulous phenotype. Executive dysfunction and impaired attention may play a key role in the gait impairment of PD, but little is known about the influence of other cognitive domains on gait in PD. In the present study, the authors objectively assessed the gait patterns of PD subjects with or without MCI in order to determine if: (1) these groups have different gait patterns during off conditions; (2) gait variables of MCI+ subjects have a poorer response to levodopa than MCI− subjects; (3) dual-task paradigms have different effects in MCI+ than in MCI− subjects; and (4) specific gait components correlate with specific cognitive domains.
Subjects were enrolled from the Movement Disorders Unit of the University of Naples Federico II if they had a diagnosis of PD according to the UK PD Brain Bank Criteria and they were classified as MCI+ if they had both a cognitive deficit not causing significant functional decline and dysfunction in at least one cognitive domain as confirmed by a consistent pattern of impairment on specific neuropsychological tests (i.e., at least 1.5 standard deviations from the norm). All subjects underwent extensive neuropsychological testing in the "on" state. Gait analysis was conducted with an optokinetic system fitted with six infrared cameras, a motion capture unit and data acquisition software. All subjects' gaits were assessed during three experimental conditions performed twice: (1) normal gait; (2) motor dual-task (walking while carrying a tray with 2 glasses filled with water); and (3) cognitive dual task (walking while performing serial 7s). PD subjects were examined in both the "off" and the "on" state. Importantly, all subjects were instructed to walk at usual speed and were not given any specific instructions regarding prioritization (walking or task).
Forty-three subjects with PD were enrolled with nineteen being classified as having MCI. Twenty healthy subjects were also enrolled. All three groups did not differ in regards to demographic and anthropometric variables and most importantly there were no significant clinical differences among the PD MCI+ and MCI− groups on clinical measures including the UPDRS, Hoehn & Yahr Staging and disease duration (which was around 5.5 years).
Key findings in MCI+ PD subjects were: (1) reduced step length and swing time and more impairment on measures of dynamic stability—these impairments were only partially ameliorated with levodopa, (2) in the dual task paradigms, step length, step length variability and swing time were not only impaired in the "off" state (as in MCI− PD subjects), these gait parameters were also impaired in the "on" state, (3) an independent factor termed "stability" which focuses on balance parameters in the analysis was highly correlated with visuospatial impairment and most clinical measures of disease progression.
This research is relevant to our practice for several reasons. First, the research demonstrates that the presence of MCI in PD is predictive of gait impairment even if other factors are held constant (disease duration, age, severity of disease). Second, it demonstrates that PD patients with MCI are more prone to gait impairment becoming a problem when trying to perform another task (the old adage of "you cannot walk and chew gum at the same time"). Third, visuospatial dysfunction is likely to be quite predictive of balance problems in PD. Finally, it reaffirms previous research demonstrating that levodopa only partially mitigates gait impairment in PD.
About Dr. John Morgan
Dr. Morgan is an Associate Professor in the Movement Disorders Program, Department of Neurology, Georgia Health Sciences University, Augusta, GA, USA. He is Director of the NPF Center of Excellence at Georgia Health Sciences University. Clinical and research interests include Parkinson's disease, Huntington's disease and restless legs syndrome.