Serotonin transporter polymorphism (5-HTTLPR) is associated with post-awakening cortisol measures in previous...

Area of Science:

• Neuroendocrinology
• Genetics
• Psychiatry

Background:

• Elevated cortisol is linked to major depressive disorder (MDD).
• Hypothalamic-pituitary-adrenal (HPA) axis functioning varies, potentially due to genetic factors like the serotonin transporter polymorphism (5-HTTLPR).
• Understanding cortisol dynamics in relation to genetics and depression is crucial.

Purpose of the Study:

• To investigate associations between cortisol awakening measures and 5-HTTLPR genotype in individuals with a history of depression versus healthy controls.
• To explore the relationship between current depressive symptom severity and cortisol indices.
• To determine if 5-HTTLPR genotype influences cortisol awakening response (CAR).

Main Methods:

• Salivary cortisol was measured in the evening and at five timepoints post-awakening (15-min intervals) in 108 individuals with a history of depression and 59 healthy controls.
• Cortisol Awakening Response (CAR) was analyzed using area under the curve with respect to ground (AUCg) and area under the curve with respect to increase (AUCi).
• Linear mixed-effects models and regression analyses were employed, with participants genotyped for 5-HTTLPR.

Main Results:

• Cortisol levels changed significantly over time, but no genotype group differences were found in the overall cortisol timecourse.
• Group differences were observed for AUCg, indicating variations in overall post-awakening cortisol output, but not for AUCi (baseline-relative increase).
• Depressive symptom severity (BDI-II) was not associated with AUCg or AUCi after covariate adjustment.

Conclusions:

• 5-HTTLPR genotype may influence overall post-awakening cortisol output (AUCg) rather than the relative increase (AUCi) in individuals with a history of depression.
• Cortisol Awakening Response (CAR) differences related to 5-HTTLPR genotype might be more detectable in total cortisol output.
• Current depressive symptom severity did not correlate with measured cortisol indices in this study.