Dissertation/Thesis Abstract

Interactive Effect of the Serotonin Transporter (5-HTTLPR) Genotype and Life Stress Predicting Bipolar Symptomatology
by Kotte, Amelia, Ph.D., University of California, San Diego, 2011, 145; 3474140
Abstract (Summary)

In patients with bipolar disorder, the serotonin transporter gene polymorphism (5-HTTLPR) is associated with effectiveness of lithium prophylaxis and with affective instability in response to environmental stress. This cross-sectional study investigated whether bipolar symptomatology at the baseline for a lithium treatment study is consistent with the diathesis-stress model.

Forty-two participants with bipolar disorder completed a battery of measures assessing demographic information, life stress, and symptoms of bipolar disorder. Participants underwent phlebotomy procedures for genotyping.

MANOVA tests showed a significant main effect for event severity (Wilk's λ = .714, F [4,31] = 2.20, p =.029). Participants with presence of a severe event scored significantly higher in depressive symptoms and were deemed more ill by the clinicians. There was a significant omnibus 3-way interaction between severe events, 5- HTTLPR, and lithium status (Wilk's λ = .367, F [4, 33] = 3.020, p =.031). A trend toward significance for 5-HTTLPR was found; i.e., lower depression scores were present in s/s and s/l and participants taking lithium, as opposed to l/l participants, when severe events were present but not when severe events were absent. There was a main effect for loss events predicting manic symptoms (F[1,38] = 4.15, p = .04). Participants with a loss event reported higher manic symptoms than those without. There was an interaction between loss events and lithium status at baseline: in participants with a loss event taking lithium, manic scores were significantly lower (&mgr; = 1.70) than in patients not taking lithium (&mgr; = 9). There was a main effect for goal-attainment events predicting symptoms of depression (F[1,38] = 5.95, p = .01). Participants with at least one goal-attainment event reported lower depressive symptoms than those without.

Findings were partially consistent with the diathesis-stress model. No interaction was found between 5-HTTLPR genotype and event severity predicting bipolar symptomatology. The results suggest lithium prophylaxis is effective in buffering against depressive symptoms when bipolar patients with at least an s 5-HTTLPR allele experience severe environmental events. Results increase understanding of gene by environment mechanisms, imply improvement of identification of patients at risk for poor prognosis and help direct therapeutic techniques.

Indexing (document details)
Advisor: Kelsoe, John R., McQuaid, John R.
Commitee: Price, Joseph M., Wall, Tamara L., Weersing, V. Robin
School: University of California, San Diego
Department: Clin Psychology (Jnt Doc SDSU)
School Location: United States -- California
Source: DAI-B 72/12, Dissertation Abstracts International
Subjects: Clinical psychology
Keywords: Bipolar disorder, Gene environment interaction, Life stress, Serotonin transporter
Publication Number: 3474140
ISBN: 9781124898476