Methods for measuring cognitive reserve (CR) are limited and controversial. Dual task cost (DTC) paradigms, assessing links between gait and cognition, are increasingly regarded as robust measures of CR.

Here, we aimed to validate a simplified methodology for a DTC paradigm in healthy volunteers for application in clinical settings as a measurement of CR.

We tested if subtracting by 7's (cognitive task) while walking (motor task) induced a DTC in a sample of 39 healthy young adults. For the cognitive task, we recorded the number of correct and incorrect subtractions, as well as the latency between subtractions. Gait parameters were recorded on a tri-axial accelerometer fixed to the left ankle. Both tasks were performed separately (single task) and simultaneously (double task) to assess the DTC. A battery for neuropsychological assessment and questionnaires to assess quality of life and affective symptoms were also applied, to measure possible correlations with the DTC.

Subtracting 7's while walking caused significant changes in gait parameters and in cognitive task performance. A significant decrease in the autocorrelation of the accelerometer signal during the dual task was also found (DTC = 37.92 ± 7.56%; P < 0.0001). This measure has not been previously used and may be a more sensitive measure of the dual task induced disturbance of the gait periodic signal pattern. Correlations between DTC and quality of life, affective or cognitive measures were not significant.

Our study provides an effective, portable and non-intrusive DTC experimental protocol that can be easily applied in clinical settings.

The authors have not supplied their declaration of competing interest.