On the benefits of wearable devices for Parkinson's disease.

Freezing of gait (FOG) is defined as episodic inability to generate an effective movement without any known cause other than parkinson-ism or gait disturbance. FOG is one of the most disabling symptoms of Parkinson's disease (PD), it affects mobility and increases the risk of falling in people with PD, making it a leading cause of hospitalization and of significantly worsening the quality of life (1). In recent years, new non-invasive intervention strategies have been implemented to decrease FOG symptoms. Thanks to technological progress, several devices have been developed as a support for the patients during diag-nosis, treatments and also everyday life. These types of interventions are based on cueing systems that rely on active stimulation. These devices are able to identify FOG states and to operate when this motor blocks occur, providing external stimuli to overcome these episodes. Hence, this work aims to provide a technological review of the literature related to wearable devices and focuses on auditory, visual, virtual and soma-tosensory cueing systems, which can provide a suitable intervention for patients with PD. The paper describes the technical functioning and effectiveness of the different reporting systems in overcoming FOG episodes. Moreover, a classification of existing devices, highlighting their advantages and disadvantages, will be provided in order to identify the ones with the best performance.