Table 1.

Structural neuroimaging-genetics studies in ADHD.

Genes	Index variants	Groups	MRI	Imaging matrix	Results	References
SLC6A3	3’ UTR intron 8 VNTR haplotype	Three SLC6A3 alleles (10/10 genotype, and the haplotypes 10–6 and 9–6)	sMRI	Bilateral striatal volumes (nucleus accumbens, CN, and putamen)	Adult ADHD 9–6 haplotype carriers ↑ 5.9% larger striatum volume relative to participants not carrying this haplotype.	Onnink et al.130
	3’ UTR VNTR	10R/10R carriers vs. 9R carriers	sMRI	Cingulate cortex thickness	10R/10R carriers: ↑ thickness in right cingulated gyrus and right BA 24.	Fernandez-Jaen et al.131
	3’ UTR VNTR	10R/10R carriers vs. 9R carriers	sMRI	PFC thickness	10R/10R carriers: ↓ cortical thickness in right BA 46 (lateral PFC).	Fernandez-Jaen et al.129
	3’ UTR VNTR	9R carriers vs. 10R/10R carriers, 4R/4R carriers vs. rest	sMRI	PFC GM and CN volume	SLC6A3 ADHD 10/10R carriers: ↓ CN volumes	Durston et al.175
	3’ UTR and intron 8 VNTR haplotype	10–6 haplotype carriers vs. non-10–6 haplotype carriers, 7R carriers vs. non-7R carriers	sMRI	Striatum, frontal cortex, and hippocampus volumes	SLC6A3 10–6 haplotype carriers: ↓ left striatal volume, irrespective of treatment.	Schweren et al.134
	3’ UTR VNTR	9R carriers vs. 10R/10R carriers	sMRI	CN volume	9R carriers: ↑ volumes of CN.	Shook et al.176
	3’ UTR VNTR, exon 3 VNTR, rs4680	9R carriers vs.10R/10R carriers; 4R/4R carriers vs.“rest	DTI	WM integrity, FA values	SLC6A3 9R carriers: no effect on WM integrity DRD4 4R/4R carriers: no effect on WM integrity	Hong et al.140
COMT	rs4680	Met carriers vs. Val/Val carriers	sMRI	Striatum, cerebellum, temporal lobe and IFG volume	ADHD Met carriers: ↓ GM volume. ADHD Val/Val: ↑ GM volume in right CN compared to ADHD Met carriers and HC.	Villemonteix et al.135
	rs4686	Met carriers vs. Val/Val carriers	sMRI	GM volume	ADHD Met carriers: ↓ GM volume in left putamen.	Shimada et al.136
	rs4680	Met carriers vs. Val/Val carriers	DTI	FA and RD values	ADHD Val/Val: ↓ FA and ↑ RD in the right cingulum (cingulated gyrus) compared to ADHD Met carriers and HC Val/Val.	Kabukcu Basay et al.141
	rs4680	Met carriers vs. Val/Val carriers	DTI	WM integrity, FA values	Met carriers: ↓ Network of WM connections linking 18” brain regions	Hong et al.140
DRD4	exon 3 VNTR	7R carriers vs. non-7R carriers	sMRI	Superior and middle frontal, anterior cingulate, and cerebellum cortices volumes	7R carriers: ↓ volumes of the superior frontal cortex and cerebellum cortex compared to non-carriers.	Monuteaux et al.133
	exon 3 VNTR	9R carriers vs. rest, 7R carriers vs. rest, S-allele carriers vs. rest	sMRI	Total GM, caudate, and putamen volume	Putamen volume, DRD4 7R carriers showed opposite age relations.	Richards et al.153
	exon 3 VNTR	7R carriers vs. non-7R carriers	sMRI	TBV, PFC, cerebellum, CN, and pallidum volume	No volumetric differences between 7R and non-7R carriers. No group × genotype interactions.	Castellanos et al.177
	exon 3 VNTR	9R carriers vs. 10R/10R carriers, 4R/4R carriers vs. rest	sMRI	PFC GM and CN volume	DRD4 unaffected siblings 7R carriers: ↑ prefrontal GM volume.	Durston et al.177
	exon 3 VNTR	10–6 haplotype carriers vs. non-10–6 haplotype carriers, 7R carriers vs. non-7R carriers	sMRI	Striatum, frontal cortex, and hippocampus volumes	DRD4 7R carriers: frontal cortex volume is associated with stimulant treatment at a younger age.	Schweren et al.134
	exon 3 VNTR	9R carriers vs.10R/10R carriers; 4R/4R carriers vs. rest	DTI	WM integrity, FA values	DRD4 4R/4R carriers: no effect on WM integrity	Hong et al.140
SLC6A4	5-HTTLPR	S carriers vs. LL carriers	sMRI	GM volume	S carriers: stress exposure is associated with ↓ GM volume in the precentral gyrus, middle and superior frontal gyri, frontal pole, and cingulated gyrus. Association of GxE interaction with ADHD symptom count was mediated by GM volume in frontal pole and anterior cingulated gyrus only.	van der Meer et al.178
	5-HTTLPR	S-allele carriers vs. rest	sMRI	GM volume	↑ positive relation between stress exposure and ADHD severity; Interactions were reflected in GM volume of cerebellum, parahippocampal gyrus, intracalcarine cortex,and angular gyrus.	van der Meer et al.179
	5-HTTLPR	S-allele carriers vs. rest	sMRI	Total GM, caudate, and putamen volume	For total GM, differential age effects were found for SLC6A4 L/L carriers, depending on the amount of positive peer affiliation.	Richards et al.153
SLC6A3	SLC6A3 3’ UTR VNTR; HTTLPR	9R carriers vs. rest, 7R carriers vs. rest, S-allele carriers vs. rest	sMRI	Total GM, caudate, and putamen volume	For total GM, differential age effects were found for SLC6A3 9R- and SLC6A4 L/L carriers, depending on the amount of positive peer affiliation.	Richards et al.153
	3’ UTR VNTR, exon 3 VNTR, rs4532	9R carriers vs. 10R/10R carriers, 7R carriers vs. non-7R carriers, C-allele carriers vs. non-C-allele carriers	sMRI	Cortical thickness	SLC6A3 9R carriers: No effect. DRD4 7R carriers: thinner right orbitofrontal/inferior prefrontal and posterior parietal cortex. ADHD 7R carriers: distinct trajectory of cortical development; normalization of the right parietal cortical region.	Shaw et al.132
SLC6A2	rs4532; rs265981, rs998424, rs3785157	2 and 3 genotype groups per SNP	sMRI	TCV, volumes of total GM and WM, CN, cerebellum, frontal, temporal, parietal lobes	NET1 SNPs: no genotype effects on GM or WM volume and no group × genotype interactions.	Bobb et al.180
DRD1	3’ UTR VNTR, exon 3 VNTR, rs4532	9R carriers vs. 10R/10R carriers, 7R carriers vs. non-7R carriers, C-allele carriers vs. non-C-allele carriers	sMRI	Cortical thickness	DRD1: no effect of genotype on the clinical outcome or cortical development.	Shaw et al.132
	rs4532; rs265981, rs998424, rs3785157	2 and 3 genotype groups per SNP	sMRI	TCV, volumes of total GM and WM, CN, cerebellum, frontal, temporal, parietal lobes	DRD1 and NET1 SNPs: No genotype effects on GM or WM volume and no group × genotype interactions.	Bobb et al.180
NOS1	exon 1f-VNTR	SS carriers vs. SL/LL carriers	DTI	WM integrity, FA and MD values	Female SS carriers: ↑ MD in right parietal WM tracts. Males: no difference between genotype groups. No genotype × diagnostic group interaction.	van Ewijk et al.181
ADRA2A	rs1800544, rs553668	C-allele carriers vs. GG carriers, T-allele carriers vs. CC carriers	DTI	White matter integrity, FA values	rs1800544 C-allele carriers: ↓ FA in the right postcentral gyrus. rs553668 T-allele carriers: ↓FA in the right middle frontal cortex.	Park et al.182
NR3C1	5-HTTLPR, rs6189, rs6198	S-allele carriers vs. rest; NR3C1 risk haplotype carriers (rs6189G and rs6198G) vs. rest	sMRI	GM volume	NR3C1 risk haplotype carriers: ↑ positive relation between stress exposure and ADHD severity	van der Meer et al.179