How to prevent cognitive overload in the walking-arithmetic dual task among patients with Parkinson’s disease

BACKGROUND: Participants with Parkinson’s disease (PD) may experience difficulty during certain dual-task (DT) tests. Thus, it is necessary to keep the cognitive load within the limits of their ability. OBJECTIVE: To identify cognitive overload and its influence on the walking and auditory addition and subtraction (AAS, all values within the range of 0–20) DT performance of patients with PD. STUDY DESIGN: A cross-sectional observational study with convenience sampling. SETTING: Outpatient clinic of the Department of Neurology. SUBJECTS: Sixteen patients with PD and 15 sex- and age- matched people elderly healthy controls (HCs). METHODS: Verbal calculation responses and gait parameters were collected from the two groups in the 2-min single arithmetic task (2-min SAT), 2-min single walking task (2-min SWT), and 2-min walking–arithmetic dual task (2-min WADT). RESULTS: The group differences in the lower-limb gait parameters increased in the 2-min WADT (P < 0.01), and those in the arm, trunk, and waist parameters did not change (P > 0.05). In the 2-min SAT, the calculation speed of the PD group was significantly lower than that of the HC group (P < 0.01). In the 2-min WADT, both groups made more errors (P < 0.05), especially the PD group (P = 0.00). PD group miscalculations occurred in the first half of the 2-min SAT but were uniformly distributed in the 2-min WADT. The HC group and PD group had subtraction self-correction rates of 31.25% and 10.25%, respectively. The PD group tended to make subtraction errors when the value of the first operand was 20 or 13.46 ± 2.60 and when the value of the second and third operands were 7.75 ± 2.51 (P = 0.3657) and 8.50 ± 4.04 (P = 0.170), respectively. CONCLUSIONS: Cognitive overload was observed in patients with PD. This was mainly reflected in the failure of gait control and accurate calculation, indicated by gait parameters of the lower limbs and accuracy of calculation. To impose a constant cognitive load, the amount added or subtracted, especially in subtraction with borrowing, should not be mixed during a sequential arithmetic problem in the DT, and equations with the value of the first operand equal to 20 or approximately 13, the value of the second operand approximately 7, or the value of the third operand of approximately 9 should be excluded in the AAS DT. TRIAL REGISTRATION: Clinical trial registration number: ChiCTR1800020158.