health
March 14, 2026
Testosterone in Boston: Why Declining T-levels in Boston Matter for All American Men
The Massachusetts Male Aging Study is one of the most important studies for understanding what’s happening to testosterone today across the Western world
TL;DR
- The Massachusetts Male Aging Study (MMAS) is a key study on male testosterone levels in the Western world.
- It tracked over 1700 men aged 40-70 from Boston between 1987 and 2004 through interviews, questionnaires, and blood samples.
- The study established prevalence of conditions like erectile dysfunction and provided reference ranges for male hormones.
- It identified risk factors for testosterone decline such as smoking and being overweight.
- MMAS revealed a significant longitudinal decline in testosterone levels over time, not solely explained by aging or lifestyle factors.
- This decline, approximately 1.6% per year for total testosterone and 3% for bioavailable testosterone at the population level, has been corroborated by studies in the US, Europe, and Israel.
- More recent research indicates this decline is also occurring in adolescents and younger men.
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