04/03/2026
As an ex-biogerontologist I’m still interested in the biology of ageing, so this paper got me interested…
If you have ADHD, you’ve likely heard of L-tyrosine, precursor to dopamine, which for many of us is the "emergency backup" when meds aren't available. But a 2025 study in Aging suggests a potential issue: higher tyrosine levels were linked to a shorter lifespan, particularly in men.
Researchers used Mendelian Randomisation (basically using genetics to simulate a lifelong clinical trial). They found that while phenylalanine (tyrosine's parent amino acid) didn't impact longevity, tyrosine itself was associated with a shorter lifespan, specifically in men, with higher genetically predicted tyrosine living about 1 year less. In women, the effect wasn’t wasn't statistically significant.
Before you bin your supplements, let’s look at the limitations:
This study looked at circulating levels and genetic predispositions, not people taking high-dose supplements. We don't know if "fixing" a deficiency with a supplement carries the same risk as having naturally high levels.�
We don’t yet know the mechanism. Is it metabolic stress? Is it how it interacts with protein-sensing pathways? The study doesn't tell us.��The fact that the impact was significantly stronger in men suggests there’s complex biology we don't fully understand yet.�
For many neurodivergent adults, tyrosine is a tool for executive function. But… we need to stop treating supplements like they are "consequence-free" versions of medication. They are bioactive. If you’re megadosing tyrosine every day because you can’t get your meds, this is a reminder that more isn't always better.
Citation: Zhao, J. V., Sun, Y., Zhang, J., & Ye, K. (2025). The role of phenylalanine and tyrosine in longevity: A cohort and Mendelian randomization study. Aging, 17(10), 2500.