Table 2. Fixed effects of linear mixed model applied to investigate group differences in the brain-predicted age difference (brain-PAD).

Main model - Comparison to C-well
Fixed effect	β-coefficient	SE	df	t-value	p-value
(Intercept)	0.09	0.10	174	0.84	0.55
Timepoint 2	0.37	0.09	121	4.10	<0.001 ***
HR-well	-0.37	0.16	25	-2.33	0.03 *
HR-MD	-0.07	0.20	25	-0.35	0.72
Timepoint 2*HR-well	-0.24	0.13	121	-1.93	0.06
Timepoint 2*HR-MD	-0.60	0.14	121	-4.23	<0.001 ***
Main model - Comparison to HR-well
Fixed effect	β-coefficient	SE	df	t-value	p-value
HR-MD	0.30	0.21	25	1.14	0.16
Timepoint 2*HR-MD	-0.36	0.14	121	-2.52	0.01 *

* p < 0.05, ** p < 0.01, *** < 0.001

Note: β-coefficients are standardised following scaling of the outcome variable.

C-well, group of participants without family history who remained well; HR-MD, group of participants at high familial risk who developed a mood disorder; HR-well, group of participants at high familial risk who remained well.