Table 3. Power spectral analysis of heart rate variability in the two groups of subjects.

Variable	NC (n = 40)	MCI (n = 40)	p	q b	adjusted p c
LFn (n.u)
baseline	48.7 (18.1)	49.2 (20.0)	0.910	0.910
standing	65.8 (17.0)	52.7 (20.0)	0.002	0.018	0.009
paced breathing	38.1 (18.0)	49.1 (18.7)	0.009	0.041	0.006
Δ standing	17.1 (16.8)	3.6 (25.7)	0.007	0.041	0.012
Δ paced breathing	−10.6 (20.7)	−0.1 (23.1)	0.036	0.092
HFn (n.u) a
baseline	30.9 (15.7)	27.5 (13.1)	0.430	0.470
standing	18.5 (10.3)	26.2 (14.3)	0.015	0.049	0.018
paced breathing	47.7 (18.5)	38.6 (17.3)	0.035	0.092
Δ standing	−12.5 (14.2)	−1.4 (13.4)	0.001	0.018	0.003
Δ paced breathing	16.7 (20.0)	11.0 (17.1)	0.374	0.422
LF/HF a
baseline	2.4 (2.2)	2.7 (2.7)	0.605	0.623
standing	5.2 (3.8)	3.4 (3.3)	0.003	0.021	0.006
paced breathing	1.2 (1.5)	1.8 (1.5)	0.014	0.049	0.039
Δ standing	2.8 (2.6)	0.7 (3.0)	<0.001	0.004	<0.001
Δ paced breathing	−1.2 (2.0)	−0.9 (2.8)	0.075	0.154

HRV indices, expressed as mean (SD), in baseline conditions and during and in response to (Δ) provocative tests (active standing, paced breathing). Significant results are shown in bold typeface.

^astatistical analyses performed on log ₁₀ - transformed variable;

^bcorrection for multiple testing by means of the Benjamini-Hochberg procedure with a 5% False Discovery Rate (FDR);

^cadjustment for potential confounders by means of multiple linear regression (see text for details). NC: normal cognition (controls); MCI: mild cognitive impairment; n.u.: normalized units; LFn: low frequency power (normalized); HFn: high frequency power (normalized); LF/HF: LF to HF ratio; Δ standing: standing HRV index - baseline HRV index; Δ paced breathing: paced breathing HRV index - baseline HRV index.