Differential aberrant connectivity of precuneus and anterior insula may underpin the diagnosis of schizophrenia and mood disorders

Table 1 Regions of interest with their Montreal Neurological Institute coordinates

Region of interest	X	Y	Z	Brodmann area
DLPFC (left)	-28	46	26	46
VLPFC–opercular part of the IFG (left)	-41	19	41	44
dACC (left)	0	32	26	24
aI (left)	-36	14	-4	48
Pc (left)	-10	-54	30	23

DLPFC: Dorsolateral prefrontal cortex; VLPFC: Ventrolateral prefrontal cortex; IFG: Inferior frontal gyrus; dACC: Dorsal Anterior cingulate cortex; AI: Anterior insula; Pc: Precuneus; X, Y, Z: Montreal Neurological Institute coordinates.

Table 2 Demographic and clinical characteristics of аll participants

	SCH patients (n = 26)	Ds patients (n = 32)	P value
Age (mean ± SD)	39.2 ± 13.2	42.9 ± 11.7	0.4481
Sex (M/F)	13/13	10/22	0.1152
Education (years)	13.6 ± 3.1	13.5 ± 3.2	0.8711
Age at onset (years)	25.8 ± 8	32.1 ± 11.8	0.0601
Episode duration (weeks)	19.6 ± 28	13.7 ± 16.8	0.1591

¹Independent samples t test.

²χ² test, P < 0.05.

SCH: Schizophrenia; Ds: Depressive syndrome; SD: Standard deviation.

Table 3 Demographic and clinical characteristics of the two depressive syndrome subgroups

	MDD patients (n = 14)	BD patients (n = 18)	P value
Age (mean ± SD)	42.4 ± 12	43.3 ± 11.8	0.2861
Sex (M/F)	5/9	5/13	0.7122
Education (years ± SD)	14.6 ± 3.8	12.8 ± 2.6	0.1971
Age at onset (years)	30 ± 12	31.5 ± 12	0.7341
Episode duration (weeks)	8.8 ± 9.3	17 ± 20	0.1971

¹Independent samples t test.

²χ² test, P < 0.05.

MDD: Major depressive disorder; BD: Bipolar disorder; SD: Standard deviation.

Table 4 Connections significantly different from zero in the depressive syndrome group

Connections	Mean	P value
dACC→DLPFC	0.146	0.029a
Pc→DLPFC	-0.239	0.002b
VLPFC⊃	-0.185	0.002b
dACC→VLPFC	0.180	0c
aI→VLPFC	-0.250	0.002b
Pc→VLPFC	-0.177	0.007b
DLPFC→dACC	0.212	0.004b
VLPFC→dACC	-0.181	0.02a
dACC⊃	-0.160	0.007b
Pc→dACC	-0.228	0.006b
aI⊃	-0.216	0.003b
DLPFC→Pc	0.090	0.047a
VLPFC→Pc	0.133	0.029a
dACC→Pc	0.090	0.049a
aI→Pc	-0.284	0c

^aP < 0.05.

^bP < 0.01.

^cP < 0.001.

⊃: Self-inhibitory connection; DLPFC: Dorsolateral prefrontal cortex; VLPFC: Ventrolateral prefrontal cortex; IFG: Inferior frontal gyrus; dACC: Dorsal anterior cingulate cortex; AI: Anterior insula; Pc: Precuneus.

Table 5 Connections significantly different from zero in the schizophrenia group

Connections	Mean	P value
dACC→DLPFC	0.172	0.004b
Pc→DLPFC	-0.384	0.001b
dACC⊃	-0.189	0.009b
aI→dACC	-0.303	0.013a
Pc→dACC	-0.366	0.001b
DLPFC→aI	0.110	0.039a
dACC→aI	0.126	0.026a

^aP < 0.05.

^bP < 0.01.

^cP < 0.001.

⊃: Self inhibitory connection; DLPFC: Dorsolateral prefrontal cortex; VLPFC: Ventrolateral prefrontal cortex; dACC: Dorsal Anterior cingulate cortex; aI: Anterior insula; Pc: Precuneus.