Table 3. Dual task costs.

Performers	good	intermediate	poor	P
Dual task costs
Walking when checking boxes [%]	11.0 (−5.4–35.8)	10.9 (−76.0–65.0)	12.8 (−40.3–58.1)	0.11
Checking boxes when walking [%]	10.4 (−83.2–53.0)	10.2 (−66.8–54.1)	12.0 (−121.0–68.5)	0.51
Walking when subtracting [%]	16.7 (−16.1–43.4)	17.3 (−38.0–58.2)	19.8 (−6.3–58.6)* #	<0.001
Subtracting when walking [%]	−15.9 (−156.9–75.4)	−22.6 (−227.4–60.5)	−17.3 (−190.1–76.8)	0.20
At least one subtraction error (proportion of cohort, %)	3.0	3.5	−1.6*	0.07

Data are presented with median and range. P-values were calculated using a logistical regression model and the likelihood ratio, with correction for age, gender, education level, Mini Mental Status Examination score and Becks Depression Inventory score. Difference of subtraction errors were calculated with Chi square test.

*p<0.05 compared to good performers;

^#p<0.05 compared to intermediate performers.