Associations between circulating cell-free mitochondrial DNA, inflammatory markers, and cognitive and physical outcomes in community dwelling older adults

Table 4 Associations of peripheral inflammatory markers with cognitive and physical outcomes (N = 672)

Outcomes	CRP β (CI)	sTNFR1 β (CI)	TNFα β (CI)	IL-6 β (CI)
Cognition
Global cognition	-0.83 (-1.91, 0.25)	-5.85 (-8.63, -3.08)	-1.01 (-2.32, 0.31)	-0.87 (-2.36, 0.62)
Working memory	-0.81 (-1.82, 0.20)	-4.01 (-6.46, -1.56)	-0.42 (-1.66, 0.82)	-0.67 (-1.94, 0.60)
Semantic memory	-0.96 (-1.92, -0.01)	-5.52 (-7.90, -3.13)	-0.24 (-1.61, 1.13)	-0.86 (-2.37, 0.64)
Perceptual speed	-1.26 (-2.34, -0.19)	-5.47 (-8.03, -2.92)	-0.81 (-2.14, 0.51)	-1.19 (-3.24, 0.86)
Perceptual orientation	-1.18 (-2.04, -0.32)	-2.95 (-5.25, -0.65)	-1.10 (-2.12, -0.08)	-0.57 (-1.65, 0.51)
Episodic memory	-0.50 (-1.59, 0.59)	-4.93 (-7.92, -1.94)	-0.91 (-2.27, 0.44)	-0.89 (-2.17, 0.39)
Physical Function
Frailty ^a	0.003 (-0.05, 0.05)	0.15 (0.03, 0.27)	-0.03 (-0.08, 0.02)	-0.01 (-0.07, 0.05)
Grip strength	-2.90 (-4.94, -0.86)	-9.69 (-15.86, -3.52)	-0.60 (-2.77, 1.57)	-2.18 (-4.66, 0.30)
Gait speed	-0.01 (-0.03, 0.003)	-0.08 (-0.13, -0.03)	-0.01 (-0.04, 0.01)	-0.01 (-0.03, 0.02)
Motor gait ^b	-0.02 (-0.05, -0.002)	-0.16 (-0.22, -0.10)	-0.01 (-0.05, 0.02)	-0.02 (-0.05, 0.01)
Motor composite score ^c	-0.03 (-0.05, -0.01)	-0.18 (-0.23, -0.13)	-0.02 (-0.04, 0.01)	-0.03 (-0.06, -0.01)

Abbreviations: CI = Confidence interval; CRP = C-Reactive protein; ccf-mtDNA = circulating cell-free mitochondrial DNA; IL-6 = interleukin-6; TNF⍺ = Tumor necrosis factor ⍺; sTNFR1 = soluble Tumor necrosis factor ⍺ receptor 1
^aFrailty is composite variable consisting of grip strength, timed walk, body mass index and fatigue. Larger values correspond to higher frailty
^bMotor gait is a z-standardized composite variable comprised of walking time, walking steps, turning time, and turning steps. Larger values correspond to less time and fewer steps to complete task
^cMotor composite score is calculated using the following items: Purdue Pegboard Test, Finger-tapping test, Time to cover 8 feet, Number of steps required to cover 8 feet, 360 degree turn time, Number of steps to complete a 360 degree turn, Leg stand, Toe stand, Grip strength, Pinch strength. Larger values correspond to better functionality
Coefficients represent the difference in the cognitive and physical outcomes per one unit increase in the inflammatory marker on the log scale. Inflammatory variables were log-transformed. Generalized estimating equations (GEE) were used to estimate association between inflammatory markers and cognitive and physical outcomes. Each coefficient was estimated from a separate GEE model. All models were adjusted for baseline age, sex, race, and education. Bold indicates p < 0.05

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