As a village doctor in southern Egypt, I see a lot of old people but had not had a lot of experience with Alzheimer’s until it struck my mother nine years ago.

Although some of my patients do suffer from the disease, life expectancy in this country is still comparatively short, and liver disease, hypertension and diabetes often kill people in the countryside before they reach extreme old age. Perhaps because it is relatively uncommon, when an elderly relative starts to get confused, family members simply assume it is another facet of growing old; they rarely see it as a health issue.