Altered intrinsic regional brain activity in male patients with severe obstructive sleep apnea: a resting-state functional magnetic resonance imaging study

Figures & data

Table 1 Demographic and clinical characteristics of patients with OSA and GSs

Characteristics	Patients with OSA (n =25)		GSs (n=25)		P*
	Mean	SD	Mean	SD
Age, years	39.4	1.7	39.5	1.6	0.946
Education, years	11.9	3.1	10.8	3.8	0.258
BMI, kg/m^2	27.8	3.4	22.9	2.1	<0.001
Total sleep time, minutes	373.6	31.8	397.4	24.9	0.005
AHI, per hour	60.0	18.6	2.2	1.3	<0.001
N1%	32.2	20.4	10.6	4.0	<0.001
N2%	45.2	17.4	48.6	6.4	0.361
N3%	14.2	9.3	21.0	5.2	<0.001
REM%	8.4	8.6	20.4	6.9	<0.001
SpO2 <90%	26.5	19.7	0.2	0.2	<0.001
Arousal index per hour	44.0	23.3	11.8	3.0	<0.001
ESS	15.2	7.3	1.1	1.1	<0.001
MoCA	25.7	2.3	27.1	2.3	0.036

Notes:

* P, independent-samples t-tests. P<0.05.

Abbreviations: AHI, apnea-hypopnea index; BMI, body mass index; ESS, Epworth Sleepiness Scale; OSA, obstructive sleep apnea; GSs, good sleepers; REM, rapid eye movement; SD, standard deviation; SpO₂ <90%, percentage of total sleep time spent at oxygen saturations less than 90%; N1%, N2%, N3%, percent of total sleep time at diagnostic polysomnography spent irrelevant stages; MoCA, Montreal Cognitive Assessment.

Figure 1 Regional homogeneity modeled in the magnetic resonance images of the subjects in the transverse orientation, shown at four different levels through the brain (A). The modeled surface of the brain shown in different orientations. The red color signifies an increase in ReHo areas, and the blue signifies a decrease in ReHo areas (B).

Notes: Compared with GSs, patients with obstructive sleep apnea showed altered regional homogeneity areas, including the right medial frontal gyrus, right superior frontal gyrus, right cluster of precuneus and angular gyrus and left superior parietal lobule, right cerebellum posterior lobe, right cingulate gyrus and bilateral cluster covering the lentiform nucleus, putamen and insula.
Abbreviations: GSs, good sleepers; L, left; R, right; ReHo, regional homogeneity.

Figure 2 Mean ReHo signal values for altered regional brain areas. Patients with OSA showed altered ReHo in the right posterior lobe of the cerebellum (0.57±0.47 versus 0.17±0.38), left lentiform nucleus (0.93±0.49 versus -0.47±0.25), right lentiform nucleus (0.07±0.35 versus −0.44±0.25), right cingulate gyrus (0.78±0.52 versus 0.20±0.32), right medial frontal gyrus (−0.36±0.43 versus 0.31±0.45), right superior frontal gyrus (−0.08±0.45 versus 0.58±0.51), right precuneus (0.73±0.44 versus 1.33±0.40), and left superior parietal lobule (0.60±0.60 versus 1.25±0.35) compared with GSs.

Abbreviations: GSs, good sleepers; OSA, subjects with obstructive sleep apnea; ReHo, regional homogeneity.

Table 2 Two-samples t-test differences in ReHo method between OSA and GSs

Conditions	Brain regions of peak coordinates	R/L	BA	V (mm^3)	t-score of peak voxel	MNI coordinates of peak voxel			P-values
OSA > GSs	Cerebellum posterior lobe (declive, culmen)	R	–	432	4.5437	3	−69	−18	<0.001
OSA > GSs	Lentiform nucleus, putamen, insula	L	13	2,160	4.9744	−27	−15	3	<0.001
OSA > GSs	Lentiform nucleus, putamen, insula	R	13	4,536	5.4834	33	−3	3	<0.001
OSA > GSs	Cingulate gyrus	R	23	675	4.3834	0	−6	42	<0.001
OSA < GSs	Medial frontal gyrus	R	11	837	−4.927	9	54	−15	<0.001
OSA < GSs	Superior frontal gyrus	R	10	567	−4.9346	18	72	3	<0.001
OSA < GSs	Precuneus, angular gyrus	R	39	540	−4.4811	42	−72	36	<0.001
OSA < GSs	Superior parietal lobule	L	7	594	−4.4816	−33	−69	54	<0.001

Notes: The between-condition statistical threshold was set at cluster size with P<0.05, voxel with P<0.001, and V ≥405 mm³, corrected for false discovery rate (FDR).

Abbreviations: R, right; L, left; BA, Brodmann’s area; V, volume; MNI, Montreal Neurological Institute; GSs, good sleepers; OSA, patients with obstructive sleep apnea; ReHo, regional homogeneity.