I’ve had some queries in recent weeks about the use of red and near infrared lights in people who have had a stroke, especially if speech has been affected.

Aphasia is the technical medical term used to describe problems with speech and/or comprehension. The Mayo Clinic website has an excellent description of the different ways that aphasia can manifest. It is frightening, because it robs you of the ability to communicate.

Margaret Naeser from Boston is a leader in photobiomodulation research in people who have had a stroke with aphasia. Her recent excellent article has a scary title – Increased functional connectivity within intrinsic neural networks in chronic stroke following treatment with red/near-infrared transcranial photobiomodulation: case series with improved naming in aphasia.

If a person has a stroke affecting the right side of the body, then the damage is on the left side of the brain. Sounds weird, but that’s the way we are wired up.

The left side of the brain holds the speech centre. Any damage to the left side of the brain can not only cause problems with the function of the right side of the face, right arm and right leg, but it can muck up the neurones that control speech and comprehension.

Naeser worked with six patients who had aphasia as a result of a past stroke, between two and eighteen years previously. She and her team looked at the effects of putting LED lights on different parts of the head. Each person was tested prior to starting the lights, with formal language tests and functional MRI scans, and these were repeated after the course of lights had been completed.

Naeser’s results showed that the most effective placement of the LED lights was on the left side and over the centre-line of the head.

Putting lights in the right side didn’t seem to work so well. It seems that putting lights directly over the damaged speech centre in the left side of the brain, plus some lights right in the centre of the head is the best way to go.

This makes biological sense. We know that the brain makes new brain cells all through our lives. We also know that when there is damaged to the brain cells, the brain’s repair mechanisms get cracking and this results in improvements to the battling cells, plus the development of new brain cells.

We know, too, that cell batteries are needed to be in good order to power the recovering and regenerating brain cells and we know that if the mitochondria are feeling a bit miserable, then the cells aren’t going to power up to full potential.

We also know that red and near infrared stimulate the mitochondria to work better.

Putting all these things together, it looks like powering up the mitochondria of the damaged neurones on the left side gives the brain the best chance to repair and regenerate the neural pathways that control speech and communication.

This is pretty stunning research. Any improvement to speech after a stroke makes a significant difference to quality of life for the patient and the family. Putting lights on the left side of your head on a daily basis isn’t a difficult thing to do, especially when there is evidence that communication can be improved.

Reference:

Increased Functional Connectivity Within Intrinsic Neural Networks in Chronic Stroke Following Treatment with Red/Near-Infrared Transcranial Photobiomodulation: Case Series with Improved Naming in Aphasia, Margaret A. Naeser, Michael D. Ho, Paula I. Martin, Michael R. Hamblin, and Bang-Bon KooPhotobiomodulation, Photomedicine, and Laser Surgery 2020 38:2, 115-131

Thanks to Connor Olson on Unsplash for the lovely photo of two blokes having a chat over coffee.