[frm88]

Needs citation for your argument. All I read today on this subject claims the contrary:

"Associations between number of children, age at becoming a parent, and dementia risk were similar for both sexes. Lifestyle and socioeconomic factors are more likely to explain the observed associations than normal pregnancy-related physiological changes."

https://pmc.ncbi.nlm.nih.gov/articles/PMC9976501/

[tsoukase]

The article doesn't compare 0 with N children.

Caring for elderly depends on the role of family in society. In my country family still plays a huge role so having no direct descendants has it's impact.