Which disease is associated with being diagnosed only through post-mortem (autopsy)?

Alzheimer's Disease is unique among the options listed in that it cannot be definitively diagnosed during a person's lifetime. It is primarily identified through a post-mortem examination, wherein specific brain changes—such as the presence of amyloid plaques and neurofibrillary tangles—can be observed. These findings are considered definitive for diagnosing Alzheimer's, highlighting the limitations of current diagnostic methods while the individual is alive.

In contrast, conditions like pneumonia, heart disease, and diabetes can typically be diagnosed through clinical evaluations, imaging studies, lab tests, and medical history prior to death. With advances in methodology, these diseases allow for effective management and treatment based on their identifiable symptoms and biomarkers while patients are still living.