In the late 1890s, a railroad worker in Frankfurt Germany noticed that his wife, Auguste Deter, was behaving oddly. Gradually her anxiety and mood changes gave way to memory loss, delusions and other signs of dementia. Committed to an institution in the care of Dr. Alois Alzheimer, Deter became the first person diagnosed with Alzheimer’s disease. A new study establishes that even her subtle, early shifts in behavior — mild behavioral impairment — were scientifically linked to what was to come.