The paper notes that further research is needed on whether there is any causative link, or merely correlation: "Further studies are warranted to determine whet

The paper notes that further research is needed on whether there is any causative link, or merely correlation: "Further studies are warranted to determine whether these findings represent an actual effect of menopausal hormone therapy on dementia risk, or whether they reflect an underlying predisposition in women in need of these treatments." It's not unreasonable to suppose that women who go to the trouble of getting hormone therapy have other conditions, or are experiencing unusually acute effects of aging.