Cholinergic dysfunction contributes to gait disturbance in early Parkinson's disease
Institute for Ageing and Health, Newcastle University, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK. . Brain
(Impact Factor: 9.2).
09/2012; 135(Pt 9):2779-88. DOI: 10.1093/brain/aws207
Gait disturbance is an early feature in Parkinson's disease. Its pathophysiology is poorly understood; however, cholinergic dysfunction may be a non-dopaminergic contributor to gait. Short-latency afferent inhibition is a surrogate measure of cholinergic activity, allowing the contribution of cholinergic dysfunction to gait to be evaluated. We hypothesized that short-latency afferent inhibition would be an independent predictor of gait dysfunction in early Parkinson's disease. Twenty-two participants with Parkinson's disease and 22 age-matched control subjects took part in the study. Gait was measured objectively using an instrumented walkway (GAITRite), and subjects were asked to walk at their preferred speed for 2 min around a 25-m circuit. Spatiotemporal characteristics (speed, stride length, stride time and step width) and gait dynamics (variability described as the within subject standard deviation of: speed, stride time, stride length and step width) were determined. Short-latency afferent inhibition was measured by conditioning motor evoked potentials, elicited by transcranial magnetic stimulation of the motor cortex, with electrical stimuli delivered to the contralateral median nerve at intervals ranging from N20 (predetermined) to N20 + 4 ms. Short-latency afferent inhibition was determined as the percentage difference between test and conditioned response for all intervals and was described as the group mean. Participants were optimally medicated at the time of testing. Participants with Parkinson's disease had significantly reduced gait speed (P = 0.002), stride length (P = 0.008) and stride time standard deviation (P = 0.001). Short-latency afferent inhibition was also significantly reduced in participants with Parkinson's disease (P = 0.004). In participants with Parkinson's disease, but not control subjects, significant associations were found between gait speed, short-latency afferent inhibition, age and postural instability and gait disorder score (Movement Disorders Society Unified Parkinson's Disease Rating Scale) and attention, whereas global cognition and depression were marginally significant. No other gait variables were associated with short-latency afferent inhibition. A multiple hierarchical regression model explored the contribution of short-latency afferent inhibition to gait speed, controlling for age, posture and gait symptoms (Postural Instability and Gait Disorder score-Movement Disorders Society Unified Parkinson's Disease Rating Scale), attention and depression. Regression analysis in participants with Parkinson's disease showed that reduced short-latency afferent inhibition was an independent predictor of slower gait speed, explaining 37% of variability. The final model explained 72% of variability in gait speed with only short-latency afferent inhibition and attention emerging as independent determinants. The results suggest that cholinergic dysfunction may be an important and early contributor to gait dysfunction in Parkinson's disease. The findings also point to the contribution of non-motor mechanisms to gait dysfunction. Our study provides new insights into underlying mechanisms of non-dopaminergic gait dysfunction, and may help to direct future therapeutic approaches.
Available from: Walter Maetzler
- "Therefore, although these latter parameters are obviously affected by PD (Schaafsma et al., 2003;Almeida et al., 2007), the pathological correlate is most probably not of dopaminergic origin. This observation is supported by the results from studies addressing mechanisms of gait impairments in PD patients and how beneficial the medication is to improve them (Blin et al., 1991;Schaafsma et al., 2003;Baker et al., 2008;Rochester et al., 2011Rochester et al., , 2012). Contrary to our results, another study investigating a similar research question (Rochester et al., 2011) detected a significant improvement of gait variability under On-medication. "
[Show abstract] [Hide abstract]
ABSTRACT: Background: In Parkinson’s disease (PD), the effects of dopaminergic medication on straight walking and turning were mainly investigated under single tasking (ST) conditions. However, multitasking situations are considered more daily relevant. Methods: Thirty-nine early to moderate PD patients performed the following standarized ST and dual tasks (DT) as fast as possible for one minute during On- and Off-medication while wearing inertial sensors: straight walking and turning, checking boxes, and subtracting serial 7s. Quantitative gait parameters, as well as velocity of the secondary tasks were analyzed. Results: The following parameters improved significantly in On-medication during ST: gait velocity during straight walking (p=0.03); step duration (p=0.048) and peak velocity (p=0.04) during turning; velocity of checking boxes during ST (p=0.04) and DT (p=0.04). Velocity of checking boxes was the only parameter that also improved during DT. Conclusion: These results suggest that dopaminergic medication does not relevantly influence straight walking and turning in early to moderate PD during DT.
Available from: Jorunn L Helbostad
- "Gait analysis provides highly relevant outcomes for the older population. It reflects both impairment-level deficits and functional status [1–3]. Temporal-spatial gait variables have repeatedly been shown to be important for identification of injury/disease [4–6], prediction of falls [7, 8], and quantification of the effect of interventions [9, 10]. "
[Show abstract] [Hide abstract]
ABSTRACT: Measurement of temporal-spatial gait variables is common in aging research with several methods available. This study investigated the differences in temporal-spatial gait outcomes derived from two different programs for processing instrumented walkway data.
Data were collected with GAITRite® hardware from 86 healthy older people and 44 older people four months following surgical repair of hip fracture. Temporal-spatial variables were derived using both GAITRite® and PKmas® processing programs from the same raw footfall data.
The mean differences between the two programs for most variables were negligible, including for Speed (mean difference 0.3 ± 0.6 cm/sec, or 0.3% of the mean GAITRite® Speed). The mean absolute percentage difference for all 18 gait variables examined ranged from 0.04% for Stride Duration to 66% for Foot Angle. The ICCs were almost perfect (≥0.99) for all variables apart from Base Width, Foot Angle, Stride Length Variability, Step Length Variability, Step Duration Variability and Step Width Variability, which were all never-the-less above 0.84. There were systematic differences for Base Width (PKmas® values 1.6 cm lower than GAITRite®) and Foot Angle (PKMAS® values 0.7° higher than GAITRite®). The differences can be explained by the differences in definitions and calculations between the programs.
The study demonstrated that for most variables the outcomes from both programs can be used interchangeably for evaluation of gait among older people collected with GAITRite® hardware. However, validity and reliability for Base Width and Foot Angle derived by PKMAS® would benefit from further investigation.
Available from: Rodrigo Vitório
[Show abstract] [Hide abstract]
ABSTRACT: The current study evaluated the effects of disease severity on the control of obstacle crossing in people with idiopathic Parkinson's disease (PD). Forty-five subjects participated in the study, including 15 patients with mild PD (classified as stage 1 to 1.5 of the Hoehn and Yahr Rating Scale), 15 patients with moderate PD (classified as stage 2 to 3 of the Hoehn and Yahr Rating Scale), and 15 neurologically healthy individuals. Groups were matched by sex, age, body mass, and body height. The obstacle crossing task required participants to walk along a pathway and step over an obstacle (half of the knee height, positioned in the middle of the pathway). Patients were tested in a typically medicated state. Kinematic data were recorded using an optoelectronic tridimensional system. The outcome measures included spatiotemporal measures of obstacle avoidance. There were no significant differences between patients with mild PD and healthy individuals. Patients with moderate PD exhibited shorter distances for leading toe clearance and leading foot placement after the obstacle than did healthy individuals. Patients with moderate PD tended to exhibit a lower leading horizontal mean velocity during obstacle crossing than did healthy individuals. We found significant negative relationships between obstacle crossing measures and disease severity (score on the motor section of the Unified Parkinson's Disease Rating Scale). These findings suggest that disease severity affects locomotor behavior during obstacle crossing in PD. Specifically, obstacle avoidance was not affected in the early stages of PD; however, bradykinesia and hypometria influenced obstacle crossing in patients with moderate PD.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.