How increased cognitive load affects the dual-task cost in healthy young adults? A randomized, double-blind sham-controlled study

Our ability to interact flexibly with the surrounding environment and achieve an adaptive goal-directed response is one of the necessities of balance control. This study aimed to examine the interaction between cognitive demand and the necessity for keeping balance in unstable conditions. We examined the effects of performing two cognitive tasks, namely the Stroop test and Wisconsin Card Sorting Test (WCST), on postural balance in healthy young adults. Stroop and the WCST test assess selective attention and cognitive flexibility in shifting between rules, respectively. Thirty-two healthy adults were included in two experimental conditions (control and treatment) in random order, separated by at least seven days. Standing balance was evaluated by the Sway Medical Mobile application in eyes open (EO) and eyes closed (EC) in different stance positions: feet apart, feet together, semi-tandem, tandem, and single-leg stance (SLS). Balance was evaluated before and after the cognitive test in each experimental condition. Our findings indicate that performing cognitively demanding tasks adversely affected the balance ability in more demanding balance tests such as the SLS with EC (P {square} 0.05). However, no significant changes were seen in other balance tests (P {square} 0.05). Additionally, no significant changes were seen in balance ability after the Stroop or Wisconsin card sorting test alone. These results confirm that performing cognitively demanding tasks significantly reduced the ability to keep balance in less stable conditions. These findings have significant implications in understanding and preventing falls and incidents resulting from an impaired balance in complex and cognitively demanding conditions.