Better Brain Fitness with Drs. Josh Turknett and Tommy Wood

Henry Mahncke is the CEO of Posit Science and the creator of BrainHQ, the most researched brain training platform in the world. A neuroscientist who did his PhD with Michael Merzenich, considered the father of adult brain plasticity, Henry has spent two decades translating brain plasticity science into tools that actually improve brain health. In this conversation, we dig into why most brain training criticism misses the point, what the largest clinical trials really show, and why the future of brain health looks a lot like the evolution of physical fitness.
In this episode:
00:00 — Introduction and Henry's background (PhD with Merzenich at UCSF, McKinsey, founding Posit Science)
07:00 — Brain training vs. cognitive training: why the distinction matters
09:00 — Brain plasticity as the driver of brain health, and why cognitive reserve is really just brain health
13:00 — Maladaptive brain plasticity: how aging actively degrades information processing through negative plasticity
18:00 — How BrainHQ exercises are designed: adaptive speed and accuracy training from psychophysics
24:00 — The transfer and generalization debate: does brain training improve real-world function?
28:00 — Clinical trial evidence: the Mayo/USC RCT, the ACTIVE study, and 300+ published papers
34:00 — The pharmaceutical analogy: why asking "does brain training work?" is the wrong question
37:00 — Who is brain training for? From post-concussive disorder to Tom Brady
44:00 — Brain training as physical exercise: the case for everyone at every age
46:00 — Real-world brain plasticity activities: racquet sports, musical instruments, foreign languages
51:00 — Josh's Brainjo origin story and what music training does for the brain
55:00 — The loss of skill learning in modern life and education
58:00 — The "dark ages" of brain health and where the field is headed
To submit a question for us to answer on the podcast, go to brainjo.academy/question.

To subscribe to the free Better Brain Fitness newsletter, join us when we record live, and get our Guide and Checklist to essential blood tests and nutrients, go to: betterbrain.fitness.
 Click here to order Dr. Wood's book, "The Stimulated Mind."
 Click here to pre-order Dr. Turknett's upcoming book, "The Genius and the Impostor"
Intro and Outro music composed and produced by Julienne Ellen.

Can a shingles vaccine cut your dementia risk by 20%?

A series of landmark studies — published in Nature, Cell, and JAMA — say yes.

In this episode, Tommy unpacks the research: how natural experiments in four countries produced one of the most compelling signals in dementia prevention, what might explain the effect beyond infection prevention, and what it means for your own vaccination decisions.
In this episode:
00:00 — Introduction
00:52 — The new data on shingles vaccination and Alzheimer's risk
01:48 — The Stanford group and their regression discontinuity methodology
03:15 — How birthday-based eligibility creates a natural experiment (Wales, Canada, Australia)
05:28 — Results: a ~20% reduction in dementia diagnoses across all countries
06:52 — The Cell paper follow-up: benefits at every disease stage (unimpaired → MCI → dementia)
07:55 — Shingrix vs. Zostavax: the US natural experiment and a potentially larger effect
09:08 — Why does it work? Preventing illness, avoiding bed rest and disuse, immunomodulation
11:29 — Neuroinflammation and possible immune system "tuning" effects
12:27 — The sex difference: greater benefit in women in most (but not all) studies
15:52 — Summary of the evidence and what it means for dementia prevention strategy
17:36 — Josh's take: number needed to treat analysis
19:15 — Heterogeneous pathways to dementia and why vaccination fits the toolkit
21:13 — Practical advice: when to get vaccinated, repeat dosing, and personal risk assessment
25:36 — Wrap-up and how to submit questions
Links & Resources:
Shingles vaccine and dementia studies: Nature (Wales, 2025), Cell (Wales follow-up), JAMA/Lancet (Canada, Australia, US)
Flu vaccine and dementia: Neurology (2026)
Tommy's book: The Stimulated Mind
To submit a question for us to answer on the podcast, go to brainjo.academy/question.

To subscribe to the free Better Brain Fitness newsletter, join us when we record live, and get our Guide and Checklist to essential blood tests and nutrients, go to: betterbrain.fitness.
To learn more about how you can boost brain fitness with neuroscience-based musical instruction, head to brainjo.academy. 
Intro and Outro music composed and produced by Julienne Ellen.

A recent study published in Nature Medicine claims a blood test can predict when you'll develop Alzheimer's disease, and it got a lot of attention. But how well does it actually work, and should you rush out and get tested?
In this episode, we break down the study behind the headlines to understand what it really shows, where the major limitations lie, and what it means for anyone thinking about getting this kind of test.
Topics and Questions Covered
What P-Tau 217 is and why it's become the leading blood-based biomarker in Alzheimer's research.

How researchers built a predictive "clock" from blood test data and what that process required.

The important distinction between having pathology in your brain and actually developing dementia.

Who should and should not be getting tested.

What a large Norwegian population study reveals about the overlap between pathology and normal cognitive function.

How biomarkers like this might eventually fit into a broader, more personalized approach to prevention.

and more!

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To submit a question for us to answer on the podcast, go to brainjo.academy/question.

To subscribe to the free Better Brain Fitness newsletter, join us when we record live, and get our Guide and Checklist to essential blood tests and nutrients, go to: betterbrain.fitness.
To learn more about how you can boost brain fitness with neuroscience-based musical instruction, head to brainjo.academy. 
Intro and Outro music composed and produced by Julienne Ellen.

In this episode, we discuss a study published in PLOS One that compared living brain tissue to post-mortem brain tissue and found dramatic molecular differences between the two.
The findings raise serious questions about decades of Alzheimer's research built on post-mortem analysis and may help explain why pharmaceutical treatments for the disease have been so disappointing

Study: A Study of RNA Splicing and Protein Expression in the Living Human Brain
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To submit a question for us to answer on the podcast, go to brainjo.academy/question.

To subscribe to the free Better Brain Fitness newsletter, join us when we record live, and get our Guide and Checklist to essential blood tests and nutrients, go to: betterbrain.fitness.
To learn more about how you can boost brain fitness with neuroscience-based musical instruction, head to brainjo.academy. 
Intro and Outro music composed and produced by Julienne Ellen.

In this episode, we dig into a recent McGill University study on computerized cognitive training and its effects on brain chemistry in older adults.
What you'll learn:
Why certain brain training games reversed a decade of age-related cognitive decline in just 10 weeks—and how researchers finally measured actual biological changes in the brain

The critical difference between activities that genuinely enhance your brain versus mental junk food like Candy Crush or Solitaire

The single organizing principle you can use to evaluate whether any cognitive activity is actually helping your brain or wasting your time

 
To submit a question for us to answer on the podcast, go to brainjo.academy/question.

To subscribe to the free Better Brain Fitness newsletter, join us when we record live, and get our Guide and Checklist to essential blood tests and nutrients, go to: betterbrain.fitness.
To learn more about how you can boost brain fitness with neuroscience-based musical instruction, head to brainjo.academy. 
Intro and Outro music composed and produced by Julienne Ellen.