Recovery from Multiple APAs Delays Gait Initiation in Parkinson’s Disease

Abstract

Background: Freezing of gait in Parkinson’s disease (PD) has been linked with deficits in inhibitory control, but causal mechanisms are not established. Freezing at gait initiation (start hesitation) is often accompanied by multiple anticipatory postural adjustments (APAs). If inhibition deficits contribute to freezing by interfering with ability to inhibit initial weight shifts in the wrong direction, then PD subjects should experience more episodes of multiple APAs than healthy controls (HCs) do. If inhibition deficits contribute to freezing by interfering with ability to release a previously inhibited step following multiple APAs, then step onset following multiple APAs should be delayed more in people with PD than in HCs.Methods: Older adults with PD and HC subjects rapidly initiated stepping in response to a light cue in blocks of simple (SRT) and choice (CRT) conditions. We recorded kinematics and ground reaction forces, and we administered the Stroop task to assess inhibitory control.Results: Multiple APAs were more common in CRT than SRT conditions but were equally common in HC and PD subjects. Step onsets were delayed in both conditions and further delayed in trials with multiple APAs, except for HC subjects in SRT trials. Poor Stroop performance correlated with many multiple APAs, late step onset, and rearward position of center of mass (COM) at cue presentation. Forward motion of the COM during the APA was higher in trials with multiple APAs than in trials with single APAs, especially in CRT trials and in PD subjects without self-reported freezing.Conclusion: Start hesitation is not caused by multiple APAs per se, but may be associated with difficulty recovering from multiple APAs, due to difficulty releasing a previously inhibited step.

Minimal Detectable Change for Balance Using the Biodex Balance System in Patients with Parkinson Disease

“…Using a force platform (eg, AMTI), Mancini et al showed that the mediolateral center of pressure displacement is greater than the anteroposterior one in patients with PD compared with age‐matched healthy patients during static standing. Other studies have demonstrated that during static standing and in the step initiation, the mediolateral center of pressure displacement is greater than the anteroposterior direction . Thus, the greater MDC on MLSI observed in the present study may be explained by changes in compensatory mechanisms (eg, anticipatory postural adjustment) that patients with PD perform in an automated manner to counterbalance the effects of reductions in APSI .…”

“…Other studies have demonstrated that during static standing and in the step initiation, the mediolateral center of pressure displacement is greater than the anteroposterior direction . Thus, the greater MDC on MLSI observed in the present study may be explained by changes in compensatory mechanisms (eg, anticipatory postural adjustment) that patients with PD perform in an automated manner to counterbalance the effects of reductions in APSI . In contrast, during unstable conditions also performed in the force platform (eg, AMTI), previous studies showed opposite results .…”

A Randomized, Controlled Trial of Exercise for Parkinsonian Individuals With Freezing of Gait

“…4,5 Individuals with FOG (freezers) show delayed step initiation associated with repetitive anticipatory postural adjustments (APAs) as if they cannot inhibit their postural preparation and release their stepping motor program. 6 In fact, FOG has been associated with small and prolonged APAs during step initiation 7 and deficits in cognitive inhibition. 5 Thus, we hypothesize that improving APAs and cognitive inhibition could contribute to decreased FOG severity.…”

Níveis de inibição pré-sináptica durante a iniciação do passo em indivíduos com e sem bloqueio da marcha na doença de Parkinson: um estudo transversal

“…Estudos têm demonstrado que o APA é identificado pelo movimento do centro de pressão e do centro de massa (Jacobs et al, 2009;Cohen et al, 2017a;De Lima-Pardini et al, 2017b;Schlenstedt et al, 2017). Uma das tarefas mais comuns de cunho funcional para avaliar o APA é a iniciação do passo (Chen e Zhou, 2011;Yiou et al, 2017) que é dividida em três etapas (Yiou et al, 2017).…”