New data shows an experimental Alzheimer’s drug modestly slowed the brain disease’s inevitable worsening. The next question is how much difference that might make in people’s lives. Japanese drugmaker Eisai and its U.S. partner Biogen announced earlier this fall that lecanemab appears to work, a badly needed bright spot after disappointments in the quest for better Alzheimer’s treatments. Tuesday, the companies released full study results. Eisai says the drug’s benefit translates to about a five-month delay in progression over the 18-month study. The Food and Drug Administration is expected to decide whether to approve the drug by early January.