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“Glucose Supplementation for Sustained Stimulant Cognition” by Johannes C. Mayer

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The Observation

I take 60mg methylphenidate daily. Despite this, I often become exhausted and need to nap.

Taking small amounts of pure glucose (150-300mg every 20-60 minutes) eliminates this fatigue. This works even when I already eat carbohydrates. E.g. 120g of oats in the morning don't prevent the exhaustion.

The Mechanism

Facts:

  • Wiehler et al. (2022) found that cognitive fatigue correlates with glutamate accumulation in the prefrontal cortex.
  • Glutamate is the brain's main excitatory neurotransmitter.
  • Excess glutamate is neurotoxic.

    • Hypothesis-1: The brain throttles cognitive effort when too much glutamate has accumulated.

    Facts:

    • Glutamate is cleared by astrocytes.
    • This process costs 2 ATP per glutamate molecule (Escartin et al. 2006).
    • The ATP comes from astrocyte glycogen stores.
    • Sickmann et al. (2009) found that blocking astrocyte glycogenolysis impaired glutamate uptake even when glucose was available.

      • Hypothesis-2: High-dose MPH increases brain glucose consumption. More neural firing means more glutamate released, faster glycogen depletion.

      Hypothesis-3: Slow-release carbs like oats provide adequate total glucose but limited delivery rate. Pure glucose absorbs quickly, keeping blood glucose elevated so astrocytes can replenish glycogen as fast as they [...]

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      Outline:

      (00:11) The Observation

      (00:39) The Mechanism

      (02:13) The Protocol

      ---

      First published:

      December 27th, 2025

      Source:

      https://www.lesswrong.com/posts/rA7wMkH3JdMRgdgLo/glucose-supplementation-for-sustained-stimulant-cognition

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      Narrated by TYPE III AUDIO.

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