ABCB1 Genetic Effects on Antidepressant Outcomes: A Report From the iSPOT-D Trial

Area of Science:

• Pharmacogenomics
• Neuroscience
• Psychiatry

Background:

• The ABCB1 gene encodes P-glycoprotein, affecting antidepressant brain concentrations.
• ABCB1 genetic variations are linked to antidepressant efficacy and side effects in prior studies.
• Cognitive impairment in major depressive disorder (MDD) predicts poor treatment outcomes, but ABCB1's role in this subgroup is unclear.

Purpose of the Study:

• To investigate ABCB1 genetic variants as predictors of antidepressant remission and side effects.
• To assess the influence of ABCB1 variants in patients with and without cognitive impairment.
• To examine these effects in a large, randomized clinical trial of MDD patients.

Main Methods:

• Genotyped 10 ABCB1 single-nucleotide polymorphisms (SNPs) in 683 MDD patients.
• Administered escitalopram, sertraline, or venlafaxine to 576 patients over 8 weeks.
• Assessed depression (QIDS-SR), side effects, and cognitive function using standardized tests.

Main Results:

• The functional SNP rs10245483 significantly impacted remission and side effect ratings.
• Patients with common homozygotes for rs10245483 showed better response and fewer side effects with escitalopram/sertraline.
• Minor allele homozygotes responded better and had fewer side effects with venlafaxine, particularly those with cognitive impairment.

Conclusions:

• The rs10245483 polymorphism differentially predicts antidepressant outcomes based on medication.
• Cognitive impairment did not diminish the predictive value of this ABCB1 SNP for treatment response or side effects.