Does Anxiety Cause Freezing of Gait in Parkinson's Disease?

Abstract

Individuals with Parkinson's disease (PD) commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and freezing of gait (Freezers) and 17 PD without freezing of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p<0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p<0.001). Freezers experienced significantly more freezing of gait episodes (p = 0.013) and spent a significantly greater percentage of each trial frozen (p = 0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare freezing of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying freezing of gait and supports the notion that the limbic system may have a profound contribution to freezing in PD.

Freezing of gait and affective theory of mind in Parkinson disease

“…Regarding anxiety, our data are in line with results of a recent study showing that freezers and non-freezers did not show differences in baseline levels of anxiety, whereas they diverged during a stressing walking paradigm [27].…”

“…It has also been hypothesized that an activation of the limbic system may contribute to the development of FOG [18]. In accordance, FOG seems to be strongly influenced by mental aspects, either emotional or cognitive, which may play an important role in its occurrence [27,29].…”

Predicting the onset of freezing of gait: A longitudinal study

“…Anxiety was also greater in transitional freezers (and continuing freezers) compared with nonfreezers regardless of time, which provides strong evidence that anxiety precedes the onset of FOG. These results are in support of previous work suggesting that anxiety is greater in freezers than in nonfreezers and might be an important contributor to the underlying mechanism of FOG . However, depression was not significantly different in transitional freezers than nonfreezers at baseline or follow‐up and therefore may not predict FOG onset.…”

The Practicalities of Assessing Freezing of Gait

“…Because it is an episodic phenomenon [4], its observation may require the use of triggering tricks, such as increased cognitive load, as in dual tasking, or stressful situations, such as reacting under time pressure [5]; in addition, FOG may disappear during the examination due to the patient paying extra attention to gait [4]. Indeed, cognitive [6] and affective factors [7] contribute to the episodic nature of FOG. Therefore, FOG assessment should start as soon as the patient stands up from the waiting room chair because it may be the single opportunity to observe it before attentional mechanisms start to suppress it.…”