Here is a government published study referred to by many promoting LLLT. Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring
Note the penetration chart down the page. It shows the near infrared only penetrates a couple millimeters. The studies that show value in neurological setting are with mice. 2 mm into a mouse skull is substantial compared to a human brain where 2 mm is not past the skull.

Here is another. New Study Shows Only High-Powered Near-Infrared Light (NIR) Regenerates Damage from Traumatic Brain It mentions the lack of penetration.

Do you have memory loss or lack of short term memory functions ? What are you doing to help you brain perform at its best ?

I have a near infrared system for a shoulder injury. It appeared to just make the inflammation worse.