Unraveling the Cognitive-Motor Interaction in Individuals With Amnestic Mild Cognitive Impairment.

PURPOSE: This study aimed to determine whether increasing the contribution of executive functions worsens dual-task performance in individuals with amnestic mild cognitive impairment (aMCI). METHODS: Fourteen individuals with aMCI (mean [SD]: 74 [4] years) and 19 control adults (71 [5] years) recalled a list of letters in the order of presentation (SPAN-O) or in alphabetic order (SPAN-A) while ascending or descending a 3-step staircase. Dual-task cost (DTC) represented the average decrement of motor and cognitive performances during dual tasks, with greater DTC indicating worse performance. RESULTS: SPAN-A (P < 0.001) and stair descent (P = 0.023) increased the DTC in both groups compared with SPAN-O and stair ascent. Furthermore, individuals with aMCI had a greater DTC (93.4 [41.2]%) than the control group (48.3 [27.9]%) for SPAN-A (P < 0.001). Dual-task cost was also greater in descent (76.6 [42.1]%) than ascent (64.0 [34.5]%) in individuals with aMCI (P = 0.024) but not in the control group (P = 0.99). Significant negative partial correlations (ß < -0.39; P < 0.05) were found between Montreal Cognitive Assessment score and DTC, while controlling for age and physical function. DISCUSSION AND CONCLUSIONS: A greater DTC in individuals with aMCI when the cognitive task requires working memory (SPAN-A) or during complex locomotor task (descent) suggests that aMCI impedes the capacity to perform 2 tasks simultaneously when higher-order cognitive processes are challenged. Furthermore, a greater DTC in our dual-task situations appears to reflect cognitive decline, as assessed by the Montreal Cognitive Assessment score. Overall, this study indicates that increasing the contribution of executive functions worsens the cognitive-motor interaction in individuals with aMCI.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A375).

Influence of working memory and executive function on stair ascent and descent in young and older adults.

This study assessed the influence of attention division, working memory and executive function on stair ascent and descent in young and older adults. Twenty young (25.5 ±â€¯2.1 yrs) and 20 older adults (68.4 ±â€¯5.4 yrs) ascended and descended a 3-step staircase with no simultaneous cognitive task (single-motor task) or while performing a cognitive task (dual-task condition). The cognitive task involved either 1) recalling a word list of the subject's word-span minus 2 words (SPAN-2) to assess the attention division effect, 2) a word list of subject's word-span (SPAN-O) to assess the working memory effect, or 3) recalling in alphabetical order, a word list of the subject's word-span (SPAN-A) to assess the executive function effect. Word-span corresponds to the longest string of words that can be recalled correctly. The duration of ascent and descent of stairs was used to assess the cognitive-motor interaction. Stair ascent and descent duration did not differ between age groups for the single-motor task, and was similar between single-motor task and SPAN-2 in both groups (p > 0.05). In contrast, stair ascent and descent duration increased with SPAN-O compared with SPAN-2 for both groups (p < 0.01). Stair ascent (p = 0.017) and descent (p = 0.008) were longer in SPAN-A than SPAN-O only in older adults. Healthy aging was not associated with a decrease in the capacity to perform motor-cognitive dual tasks that involved ascending and descending of stairs when the cognitive task only required working memory. However, the decrease in dual-task performance involving executive functioning may reflect a subclinical cognitive decline in healthy older adults.