This article suggests that the following procedure may offer preemptive protection against common forms of dementia, other than due to traumatic brain injury:
1. Use gene therapy to deliver a photoexcitable gene to most hippocampal neurons, and ideally most brain neurons. The gene is responsible for the strengthening of synaptic function.
2. Wait for the patient to exhibit memory deficits, perhaps many years later.
3. Bombard the brain with the "magic" light frequency, thereby restoring previously inaccessible memories as soon as the synapse function is sufficient.
LLLT already does this, to some extent, without gene therapy. The method above would offer additional protection.