Changes in Oxyhemoglobin Concentration in the Prefrontal Cortex during Cognitive-Motor Dual Tasks in People with Chronic Obstructive Pulmonary Disease

Figures & data

Table 1. Characteristics of healthy older adults and patients with COPD.

Characteristic	Older Adults	Patients with COPD	p-value
Sex (n of M:F)	9M:11F	9M:6F	0.500
Age (y)	69.1 ± 6.9	70.7 ± 8.0	0.531
Height (m)	1.64 ± 0.09	1.69 ± 0.10	0.134
Weight (kg)	72.8 ± 14.8	78.5 ± 16.7	0.304
BMI (kg/m^2)	26.9 ± 4.4	27.3 ± 4.6	0.786
FEV1 (% predicted)	92.6 ± 11.7	52.3 ± 20.3	<0.001
FEV1/FVC (% predicted)	106.0 ± 6.4	58.9 ± 24.5	<0.001†
MoCA	26.1 ± 2.9	24.2 ± 2.6	0.032
Number of comorbidities	2.2 ± 2.5	5.0 ± 3.2	0.001†
Number of medications	1.5 ± 1.6	5.9 ± 3.8	<0.001†
IPAQ - Activity Level (MET-min/week)	5893 ± 9162	2140 ± 1870	0.091†
SLS Duration (s)	26.8 ± 27.5	8.2 ± 13.4	0.008†
Digit Span Forward - n (%)	20 (100)	15 (100)	1.000
Digit Span Backward - n (%)	15 (75)	10 (67)	0.712

Data are presented as mean ± SD or n (%) unless stated otherwise. BMI: body mass index; F: female; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; IPAQ: International Physical Activity Questionnaire; M: male; MET: metabolic equivalent of task; MoCA: Montreal Cognitive Assessment; n: number of participants who correctly recalled 5 digits sequence(s); SLS: single leg stance; p values are for differences tested by unpaired t tests between older adults and patients with COPD and † indicates p values tested using the non-parametric Mann Whitney U test.

Figure 1. The ΔO₂Hb in the right (A) and left (B) dorsolateral PFC during the preferred and fast paced walking single and dual tasks in healthy adults and patients with COPD. The ΔO₂Hb during preferred and fast walk were higher in patients with COPD compared to older adults in the right dorsolateral PFC. In older adults, ΔO₂Hb was higher during preferred paced walking dual versus single task in the right and left dorsolateral PFC and during fast paced walking dual versus single task in the right dorsolateral PFC (A).

* indicates statistical significance at p < 0.05. BS: backwards spelling; FPW: fast paced walking; PPW: preferred paced walk.

Table 2. Performance of healthy older adults and patients with COPD on cognitive and motor tasks.

Characteristic			Healthy Older Adults	Patients with COPD	p-value†
Velocity	(m/min) except DTE	PPW	73.4 ± 8.6	61.4 ± 13.0	0.005
		PPW + BS	64.7 ± 11.8**	56.4 ± 9.3*	0.025
		DTE of PPW + BS	−11.7 ± 12.8%	−6.3 ± 15.0%	0.130
		FPW	97.3 ± 10.4	82.8 ± 12.4	0.001
		FPW + BS	77.5 ± 12.4***	68.6 ± 11.4***	0.035
		DTE of FPW + BS	−19.9 ± 12.4%	−17.2 ± 6.6%	0.226
BS Accuracy	Words Spelled Correctly (% Accuracy)	BS	8 ± 3 (86.6 ± 17.9)	7 ± 4 (79.6 ± 28.8)	0.281 (0.422)
		PPW + BS	6 ± 2*** (80.1 ± 24.9)	5 ± 3* (71.6 ± 31.8)	0.538 (0.401)
		DTE of PPW + BS	−33.0 ± 28.8%	−14.3 ± 89.1%	0.120
		FPW + BS	5 ± 2*** (76.1 ± 23.9)	4 ± 3* (66.5 ± 36.9)	0.911 (0.392)
		DTE of FPW + BS	−43.2 ± 18.6%	−16.2 ± 116.8%	0.165

Data are presented as mean ± SD. COPD, chronic obstructive pulmonary disease; BS, backwards spelling; DTE, dual task effect; FPW, fast paced walk; PPW, preferred paced walk. † p values for comparisons between groups. *, **, *** for within group differences between single and the corresponding dual task.

* p < 0.05, ** p < 0.001, *** p < 0.0001.

Table 3. Summary of regression statistics for the predictor variables.

Predictor Variables	Unstandardized Coefficients		Standardized Coefficients	t	p
	B	SE B	β
Model 1: Association of predictor variables to left dorsolateral PFC ΔO2Hb during preferred paced walking dual task
FEV1 (% predicted)	−0.011	0.006	−0.353	−1.986	0.056
Single leg stance duration	0.011	0.006	0.336	1.925	0.064
MoCA scores	−0.022	0.047	−0.080	−0.473	0.640
R^2=0.178, SE of the estimate = 0.761, df = 30, p = 0.113
Model 2: Association of predictor variables to right dorsolateral PFC ΔO2Hb during preferred paced walking dual task
FEV1 (% predicted)	−0.013	0.005	−0.411	−2.424	0.022
Single leg stance duration	0.011	0.006	0.322	1.947	0.061
MoCA scores	−0.055	0.045	−0.196	−1.213	0.235
R^2=0.254, SE of the estimate = 0.734, df = 30, p = 0.030

Abbreviations: df: degrees of freedom; FEV₁: forced expiratory volume in 1 s; MoCA: Montreal Cognitive Assessment; PFC ΔO₂Hb: prefrontal cortex changes in oxygenated hemoglobin; SE: standard error.