Testosterone level, androgen receptor polymorphism, and depressive symptoms in middle-aged men

Area of Science:

• Endocrinology
• Psychiatry
• Genetics

Background:

• Testosterone levels naturally decrease with age.
• Testosterone deficiency symptoms overlap with depression symptoms.
• Expression of these symptoms varies among individuals.

Purpose of the Study:

• To investigate the relationship between testosterone levels, androgen receptor (AR) CAG repeat length (CAG RL), and depression in aging men.
• To explore if genetic factors, specifically AR CAG RL, influence the association between testosterone and depression.

Main Methods:

• Assessed total testosterone levels and AR CAG repeat length in 1000 men (mean age 62.6).
• Diagnosed depression using the Center for Epidemiologic Studies-Depression Scale (CES-D).
• Analyzed the association between testosterone, CAG RL, and depression using bivariate and logistic regression analyses.

Main Results:

• 11% of men in the study sample were diagnosed with depression.
• Neither total testosterone nor CAG RL alone was associated with depression.
• Depression was significantly inversely associated with total testosterone only in men with shorter AR CAG repeat lengths.

Conclusions:

• Androgen receptor (AR) CAG repeat length, a genetic marker, may influence how testosterone deficiency affects the central nervous system.
• Genetic variations in AR function could mediate the expression of psychiatric symptoms related to low testosterone in aging men.