Human Growth and Development / Unit 15 HGD 2146 worked example, 60 to 90 seconds
Alzheimer's Disease: Pathology
The idea
Alzheimer's disease is the most common dementia: progressive and fatal, affecting memory first, then other cognition, then motor skills. Most people live about six to ten years after noticeable symptoms. Its hallmarks are amyloid plaques, fragments of beta-amyloid protein gathering between neurons, and neurofibrillary tangles, twisted tau protein inside neurons, with tissue death especially in the hippocampus. Age is the biggest risk factor, and APOE4 is the best-known risk gene.
In practice
A brain scan showing a shrunken hippocampus, and under the microscope, plaques between cells and tangles within them.
Where people slip
Plaques and tangles increase with age in most people; beyond the normative range they mark mild cognitive impairment and Alzheimer's. Exam items often ask where each lies: plaques outside neurons, tangles inside.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Human Growth and Development