Some scientific research in the field:
https://www.neurology.org/doi/10.1212/WNL.0000000000012388 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960356/ https://pubmed.ncbi.nlm.nih.gov/30276939/ https://pubmed.ncbi.nlm.nih.gov/19459177/
Peace be upon you. Dementia or "dementia" is a disease that increases with age, including memory weakness in addition to the ability to think, concentrate, and perform daily activities, as well as changes in personality and mood; the most famous of its forms is Alzheimer's disease.
Many studies indicate that activating mental activity in the elderly reduces the likelihood of their contracting dementia and delays the age of onset in those who contract it. One of these is a recent study published in the journal "Neurology" (Neurology) entitled: "Mental Activity and Its Relationship to the Onset of Alzheimer's Dementia."
This study concluded that a lifestyle that includes mental activity in the elderly may delay their contracting Alzheimer's disease by up to five years, and there are other studies that support this direction.
This is a message to all of us to maintain and activate mental activity in the elderly as much as possible, and one of the best ways to achieve this is to memorize and contemplate the Noble Quran.