COMT genotype affects brain white matter pathways in attention-deficit/hyperactivity disorder

Area of Science:

• Neuroscience
• Genetics
• Psychiatry

Background:

• Dopamine availability influences brain maturation.
• Attention-deficit/hyperactivity disorder (ADHD) is associated with genetic variations affecting dopamine pathways.
• The catechol-O-methyltransferase (COMT) Val158Met polymorphism is a key genetic factor in dopamine regulation.

Purpose of the Study:

• To characterize whole-brain white matter connectivity differences in youth with ADHD based on COMT Val158Met genotype.
• To investigate the association of dopamine transporter (DAT1) and dopamine D4 receptor (DRD4) gene polymorphisms with white matter integrity in ADHD.
• To examine the relationship between white matter integrity, ADHD symptom severity, and methylphenidate (MPH) treatment response.

Main Methods:

• Diffusion tensor imaging (DTI) and whole-brain tractography were used to analyze white matter connectivity.
• An imaging connectomics approach was employed to compare COMT Val-homozygous and Met-carrier youth with ADHD.
• The continuous performance test (CPT) assessed attention levels before and after MPH treatment.

Main Results:

• Youth with ADHD carrying the COMT Met-allele showed significantly weakened white matter connectivity compared to Val-homozygous individuals.
• Fractional anisotropy (a measure of white matter integrity) correlated with CPT performance and improvement after MPH treatment.
• Altered white matter connectivity was specifically linked to COMT genotype, not DAT1 or DRD4.

Conclusions:

• White matter connectivity in youth with ADHD is significantly associated with COMT Val158Met genotypes.
• Genetic variability in dopamine-related genes plays a crucial role in the human connectome and should be considered in ADHD research.
• These findings highlight the importance of considering genetic polymorphisms in understanding brain connectivity and treatment response in ADHD.