The Longevity Letter #9: Your commute is aging your brain (but cough medicine might save it)
Discover how your daily commute accelerates brain aging, the common $5 cough syrup showing promise for dementia, and the massive FDA reversal on hormone therapy that challenges decades of medical dogm
The Longevity Letter
Longevity & Health Insights
By Dr. Hillary Lin, MD
Hi ,
I completed another trip around the sun last week, and yet with all these biological age tests I have no idea how old I am! (I range from 22-37 years old, apparently.) I celebrated by going on a 6-hr scavenger hunt and doing 9 hours puzzling in escape rooms.
Meanwhile, this week in longevity has been dominated by breakthrough news in brain health and a major FDA reversal on women's health. From discovering a "hidden" dementia that's been misdiagnosed for decades to repurposing cough medicine for brain protection, the field is moving fast.
Let's dive in.
The Quiet Dementia Diagnosis Revolution
A quiet revolution is happening in memory loss diagnosis. Earlier this year, researchers published the first clinical criteria for LATE (limbic-predominant age-related TDP-43 encephalopathy)—a disease that affects 40% of elderly brains but perfectly mimics Alzheimer's symptoms while involving completely different pathology.
Now the FDA has approved the first blood test for Alzheimer's diagnosis—Fujirebio's Lumipulse G test—with over 90% accuracy for just $500 (versus $5,000-8,000 PET scans).
Together, these developments mean doctors can finally distinguish between different types of dementia in living patients. If you test negative for amyloid but have memory concerns, you might have LATE instead—and that matters because LATE often progresses more slowly and will require entirely different treatments.
This matters because Alzheimer's affects 10% of those over 65 today, expected to double by 2050. Now, for the first time, we can distinguish between different types of dementia and match patients to the right treatments.
When Cough Medicine Becomes Brain Medicine
Sometimes the most important discoveries hide in plain sight. Ambroxol, a $5 European cough medicine, is showing remarkable promise for Parkinson's dementia. When Canadian researchers gave it to patients, those on placebo deteriorated over 12 months while ambroxol patients remained stable. Those with high-risk genes actually improved cognitively.
The mechanism is elegant: ambroxol supercharges glucocerebrosidase, a cleanup enzyme that removes toxic waste from brain cells. With decades of safety data (even during pregnancy), this raises the tantalizing possibility of genetic testing for preventive treatment years before symptoms appear.
The FDA's Historic Hormone Reversal
In a stunning development, FDA Commissioner Marty Makary assembled a panel of experts on July 17th and delivered a remarkable admission: "Fifty million-plus women have not been offered the incredible potential health benefits of hormone replacement therapy because of medical dogma."
For 23 years, hormone therapy has carried the FDA's most severe warning label following the 2002 Women's Health Initiative study. But subsequent analysis revealed a critical flaw: the average participant was 63 - more than a decade past menopause. When researchers separated by age, women who started hormones before 60 actually had lower rates of heart disease and death.
The panel focused on removing warnings for low-dose vaginal estrogen, which treats debilitating symptoms like painful sex and urinary tract infections with virtually no cancer risk. But Makary hinted at broader changes, potentially rehabilitating one of modern medicine's most controversial treatments.
If warnings are removed, millions of women could regain access to therapies that dramatically improve sleep, mood, sexual function, and bone health during menopause.
What This All Means for You
We're witnessing a remarkable convergence: environmental risks are being quantified, biological age is becoming measurable, diagnostic tools are getting precise, and therapeutic options are expanding rapidly.
The key insight emerging from 2025's research is that aging isn't inevitable or uniform. Brain aging can be slowed through environmental modifications and emerging therapies. Medical "truths" that seemed settled - like hormone therapy dangers - are being overturned by better science.
For anyone focused on longevity, the message is clear: we now have both the tools to assess individual risk and an expanding arsenal of interventions to potentially change outcomes. The future of precision medicine for healthy aging is arriving faster than most people realize.
Hillary Lin, MD
Co-Founder & CEO
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