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The aim of this randomized double blinded sham-controlled study was to determine the effect of cerebellar anodal transcranial direct current stimulation (a-tDCS) on online and offline motor learning in healthy older individuals. Thirty participants were randomly assigned in experimental (n = 15) or sham tDCS (n = 15) groups. Participants in experimental group received 2 mA cerebellar a-tDCS for 20 min. However, the tDCS was turned off after 30 seconds in sham group. Response time (RT) and error rate (ER) in serial RT test were assessed before, during 35 minutes and 48 h after the intervention. Reduction of RT and ER following the intervention session was considered as short-term (35 min post intervention) and long-term offline learning (48 h post intervention), respectively. Online RT and ER reduction were similar in both groups (P > 0.05). RT was significantly reduced 48 hours post intervention in cerebellar a-tDCS group (P = 0.03). Moreover, RT was significantly increased after 35 minutes and 48 hours in sham tDCS group (P = 0.03, P = 0.007), which indicates a lack of short-term and long-term offline learning in older adults. A-tDCS on cerebellar region produced more short-term and long-term offline improvement in RT (P = 0.014, P = 0.01) compared to sham tDCS. In addition, online, short-term and long-term (48 h) offline error reduced in cerebellar a-tDCS as compared to sham-control group, although this reduction was not significant (P > 0.05). A deficit suggests that a direct comparison to a younger group was made. The findings suggested that cerebellar a-tDCS might be useful for improvement of offline motor learning in older individuals.

The aging population is growing rapidly. Risk of falling is higher in older people compared to young adults due to several reasons including poor posture and balance. The main aim of this study was to investigate the effect of cerebellar anodal transcranial direct current stimulation (a-tDCS) on static and dynamic postural stability in older individuals. Twenty-nine older adults participated in this study and were randomly allocated to two groups of active a-tDCS (experimental; n = 14) or sham tDCS group (n = 15). Experimental group received cerebellar a-tDCS for 20 min with intensity of 1.5 mA. Anterior-posterior and medial-lateral postural stability indices (postural sway) in addition to Berg Balance Score were measured before and after the intervention. Postural sways in static and dynamic postural tasks were significantly decreased (P < 0.05) after cerebellar a-tDCS, in addition to Berg Balance Score that increased significantly in active cerebellar a-tDCS group (P < 0.05). However, there were no significant changes in postural stability indices or Berg Balance Score in sham group (P > 0.05). The findings indicated immediate effect of cerebellar a-tDCS on improvement of postural control and balance in older individuals.

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