Table 4.

Neuroimaging Results. Topography and statistical details of significant relationships between BD LiTD and boundary deformation on the left/right accumbens nuclei shape morphometric features. Effects have been assessed through linear regression analyses and ANOVA comparisons between BD groups stratified according to LiTD (i.e. BD_LiTD-, BD_LiTD+, BD_NoLi) and HC and related post-hoc analyses. Clinical correlates (depressive/hopefulness BD symptoms scores) of L-Accu core inward deformation are also reported.

Anatomical region	Results	Cluster Extent (mm3)	R2/F/t	Statistical peak p (TFCE-corrected)	MNI Coordinates of the statistical peak
					x	y	z
Regression Analyses
Left Nucleus Accumbens core	Positive Correlation	68	0.1	0.031*	−15	19	−6
Right Nucleus Accumbens core	Positive Correlation	56	0.12	0.016*	10	14	−4
Right Nucleus Accumbens shell	Negative Correlation	136	0.17	0.002*	8	13	−10
ANOVA
Left Nucleus Accumbens core		47	F(3;144) = 4.6	0.01*	−11	16	−4
Right Nucleus Accumbens shell		55	F(3;144) = 3.5	0.025*	8	13	−9
Post-Hoc
Left Nucleus Accumbens core	BP_LiTD- < HC	17	2.72	0.027*	−10	16	−9
Left Nucleus Accumbens core	BP_NoLi < HC	47	3.5	0.002*	−10	16	−9
Left Nucleus Accumbens core	BP_NoLi < BP_LiTD+	47	2.32	0.016*	−10	9	−6
Right Nucleus Accumbens shell	BP_NoLi > BP_LiTD+	55	3.11	0.005*	8	14	−10
Right Nucleus Accumbens shell	BP_NoLi > HC	55	2.58	0.005*	10	18	−9
Clinical Correlates of Left Nucleus Accumbens core
HAM-Dsom	Positive Correlation	43	0.1	0.005*	−12	10	−6
HAM-Dtot	Positive Correlation	41	0.07	0.02*	−12	9	−6
BHStot	Positive Correlation	18	0.05	0.03*	−9	16	−3

TFCE, Threshold-Free Cluster Enhancement; Coordinates are in Montreal Neurological Institute (MNI) Space. BD_LiTD-, bipolar disorder patients with lithium duration treatment shorter then 50% of illness duration; BD_LiTD+, bipolar disorder patients with lithium duration treatment longer then 50% of illness duration; BD_NoLi, bipolar disorder patients never treated with lithium; HC, healthy control subjects. HAM-Dsom, somatic subscale from Hamilton Depression Rating Scale; HAM-Dtot, total score from Hamilton Depression Rating Scale; BHStot, total score from Beck Hopefulness Scale.

^⁎Statistically significant differences at p < 0.05.