Effects of Recent Stress and Variation in the Serotonin Transporter Polymorphism (5-HTTLPR) on Depressive Symptoms: A Repeated-Measures Study of Adults Age 50 and Older.
Depending on genetic sensitivity to it, stress may affect depressive symptomatology differentially. Applying the stress-diathesis hypothesis to older adults, we postulate: (1) recent stress will associate with increased depressive symptom levels and (2) this effect will be greater for individuals with at least one short allele of the serotonin transporter gene promoter region (5-HTTLPR). Further, we employ a design that addresses specific limitations of many prior studies that have examined the 5-HTTLPR × SLE relation, by: (a) using a within-person repeated-measures design to address fluctuations that occur within individuals over time, increase power for detecting G × E, and address GE correlation; (b) studying reports of exogenous stressful events (those unlikely to be caused by depression) to help rule out reverse causation and negativity bias, and in order to assess stressors that are more etiologically relevant to depressive symptomatology in older adults. The sample is drawn from the Health and Retirement Study, a U.S. population-based study of older individuals (N = 28,248; mean age = 67.5; 57.3 % female; 80.7 % Non-Hispanic White, 14.9 % Hispanic/Latino, 4.5 % African American; genetic subsample = 12,332), from whom measures of depressive symptoms and exogenous stressors were collected biannually (1994-2010). Variation in the 5-HTTLPR was characterized via haplotype, using two single nucleotide polymorphisms (SNPs). Ordered logit models were constructed to predict levels of depressive symptoms from 5-HTTLPR and stressors, comparing results of the most commonly applied statistical approaches (i.e., comparing allelic and genotypic models, and continuous and categorical predictors) used in the literature. All models were stratified by race/ethnicity. Overall, results show a main effect of recent stress for all ethnic groups, and mixed results for the variation in 5-HTTLPR × stress interaction, contingent upon statistical model used. Findings suggest there may be a differential effect of stressors and 5-HTTLPR on depressive symptoms by ethnicity, but further research is needed, particularly when using a haplotype to characterize variation in 5-HTTLPR in population-based sample with a diverse ethnic composition.
Department of Psychology, University of Southern California, 3620 South McClintock Ave, SGM 501 MC 1061, Los Angeles, CA, 90089-1061, USA. arpawong@usc.edu.
Thalida E
http://orcid.org/0000-0001-9671-9535
TE
Arpawong
Dornsife Center for Economic and Social Research, University of Southern California, Los Angeles, CA, USA.|RAND Corporation, Santa Monica, CA, USA.
Jinkook
J
Lee
Dornsife Center for Economic and Social Research, University of Southern California, Los Angeles, CA, USA.|RAND Corporation, Santa Monica, CA, USA.
Drystan F
DF
Phillips
Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA.
Eileen M
EM
Crimmins
Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
Morgan E
ME
Levine
Department of Psychology, University of Southern California, 3620 South McClintock Ave, SGM 501 MC 1061, Los Angeles, CA, 90089-1061, USA.|Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA.
Carol A
CA
Prescott
D000368:Aged; D000483:Alleles; D003863:Depression / Q000235:genetics* / Q000378:metabolism; D003866:Depressive Disorder / Q000235:genetics; D005006:Ethnicity / Q000235:genetics; D005260:Female; D059647:Gene-Environment Interaction; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D008016:Life Change Events; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D013315:Stress, Psychological / Q000150:complications* / Q000235:genetics
D050486:Serotonin Plasma Membrane Transport Proteins
5-HTTLPR; Depressive symptoms; G × E; Older adults; Race differences; Stressful life events