This interesting Health Alert from John Hopkins discusses the different memory systems — episodic, semantic, procedural, and working — of the brain and how they are affected by Alzheimer’s disease…
Normal aging leads to changes in the brain, especially in areas involved in learning and memory. Some neurons shrink; others are disabled by damaging molecules called free radicals. Daily “insults,” such as high blood pressure or elevated low-density lipoprotein (LDL) cholesterol, also take their toll.
Over time, these changes can make it more difficult for an older person to learn new tasks or to retrieve information from memory, such as someone’s name. With Alzheimer’s disease, the damage is more severe and ultimately affects larger regions of the brain.