Final answer:
Alzheimer's disease was historically diagnosed definitively only after death by detecting amyloid plaques and neurofibrillary tangles. Advances now allow for earlier detection through imaging and genetic markers. Identifying early signs and biomarkers for Alzheimer's improves chances for earlier and potentially more effective treatment.
Step-by-step explanation:
Until recently, the only definitive method to diagnose Alzheimer's disease was through postmortem examination to identify characteristic abnormalities such as amyloid plaques and neurofibrillary tangles. These pathological hallmarks, along with a general shrinking of brain volume and severe loss of neurons in the hippocampus, were confirmed upon a patient's death. However, advancements in medicine have led to new diagnostic approaches, including imaging techniques using Pittsburgh Compound B (PiB) for early detection of amyloid plaques, and research into biomarkers in bodily fluids such as blood and cerebrospinal fluid. The genetic component of Alzheimer's, with five new genes identified as raising the likelihood of developing the disease, also provides clues for early detection and potential therapeutic targets.