Namibia, AfricaRelatives of Ndikuhoole Johanna Nakamhela began noticing the changes eight years ago when she struggled to recall significant moments in her life. She also seemed anxious when mingling with members of her church, something she’d done easily in her decades as a minister’s wife. These changes weren’t typical of the normal aging process, her doctor said, and a brain scan confirmed as much.

Now, when the 77-year-old Nakamhela potters in her kitchen at home in Kalkfeld, a small town just north of the Namibian capital, a caregiver hovers nearby to ensure that she doesn’t leave a pot unattended on the stove or get into trouble with an open gas flame. Her changing brain state often seems to trap her in a