Alzheimer’s disease has been described as “the great unlearning.” But what does it reveal about the nature of human identity? What remains when memory unravels? Alan Dienstag is a psychologist who has led support groups with early Alzheimer’s patients, as well as a writing group he co-designed with the novelist Don DeLillo. He’s experienced the early stages of Alzheimer’s as a time for giving memories away rather than losing them.