I don't know of any project on social marketing and the mental health problems in the elderly, but I've found these:

https://www.ncbi.nlm.nih.gov/books/NBK316211/

Article Social interaction and cognitive decline: Results of a 7-yea...

https://www.uptodate.com/contents/safety-and-societal-issues-related-to-dementia

Thank you, Stephen, that` s very helpful.

The Mental Health Foundation and the Joseph Rowntree Foundation have both done interesting work in the past on this subject. The issue is very much linked with loneliness. The social marketing can be addressed to the older people themselves or to the supporters/communities that might help them address their mental health issues or vulnerabilities.