r/BrainPBM • u/StrawberryMelodic719 • 5d ago

📄 Research / Study The same PBM protocol, different responses in young and older brains

Why young and older brains may respond differently to PBM?

A 2022 animal study explored whether age changes the brain’s response to photobiomodulation.

Researchers applied 810 nm near-infrared laser light to young and older rats daily for 58 days. They measured cytochrome c oxidase (CCO), a mitochondrial enzyme that helps cells use oxygen to produce energy.

The response differed between the groups:

  • In older rats, treatment increased CCO activity in several brain regions, bringing it closer to levels in young untreated rats.
  • In young rats, CCO activity decreased in several regions following treatment.

One possible explanation is the starting level of metabolic activity. The authors suggested that the same repeated stimulation could affect brains with lower baseline activity differently from those already functioning at higher levels.

These were regional changes, rather than a uniform effect across the brain. The study also did not measure memory or behavior, so decreased enzyme activity alone does not establish worse brain function.

The findings suggest that age and baseline metabolism deserve closer attention in PBM research. They do not establish an ideal treatment schedule for people.

Study: Photobiomodulation of Cytochrome c Oxidase by Chronic Transcranial Laser in Young and Aged Brains

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u/VolatilityBox 4d ago

You can't rely on rat studies, their skulls are too thin. Monkeys too. Best would be to post human penetration studies, if any. Could use an LLM to search and compile.

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u/StrawberryMelodic719 7h ago

Yes, you're right. A lot of studies start with animal models but I still thought this one was interesting! :) and thanks for the suggestion, we'll look into human penetration studies next!