Serotonin Transporter Gene Promotor Polymorphism (5-HTTLPR) Associations with Number of Psychotropic Medication Trials in a Tertiary Care Outpatient Psychiatric Consultation Practice

Objective: The authors tested the hypothesis that the short allele of 5-HTTLPR is associated with number of psychotropic medication trials as a measure of treatment-resistance or intolerance in psychosomatic medicine (PM) outpatients. Methods: Review of Mayo Clinic PM outpatient 2008 records identified 44 (20.6%) who had 5-HTTLPR genotype tests. A univariate analysis screened for factors that could account for number of medication trials. Logistic regression then determined degree of association between 5-HTTLPR genotype category and number of pharmacological trials. Results: Univariate analysis revealed significant differences across the ordinal genotype spectrum long/long, short/long, short/short in mean number of overall psychotropic medication trials (8.9, 14.8, 18.0, P = 0.002), mean number of antidepressant trials (4.3, 7.2, 8.1, P = 0.018), mean number of mood stabilizer trials (0.8, 1.9, 2.3, P = 0.008), percent living alone (7%, 25%, 50%, P = 0.020), reported family history of depression (93%, 65%, 40%, P = 0.006), and reported family history of chemical dependency treatment (50%, 35%, 10%, P = 0.050). There were trends for differences in consultation reason for unexplained symptoms (14%, 25%, 50%, P = 0.063), and diagnoses of somatoform disorder (7%, 30%, 40%, P = 0.060), and generalized anxiety disorder (43%, 65%, 80%, P = 0.064). After controlling for other differences, presence of the short allele remained associated with number of psychotropic medication trials (OR 4.779, 95% CI 2.263-6.771, P = 0.004), and number of antidepressant trials (OR 1.591, 95% CI 1.072-2.762, P = 0.019). Conclusion: 5-HTTLPR testing may identify PM outpatients at higher relative risk for pharmacotherapy treatment non-response or intolerance who may benefit from alternative or augmentative medication recommendations or non-pharmacological interventions.