Question

One of the first signs of Alzheimer's Disease is short term memory inpairment. On the other hand the hippocampus and the entorhinal cortex are one of the first areas damaged by AD and these two are involved in the process of turning short ther memory into long term memory. Why is short term memory inpairment one of the first signs of AD and not the ability to form long term memories? Is the short term memories formation linked to the hippocampus also?

Answer 1

The hippocampus is where short-term memories are turned into long-term memories. These are then stored elsewhere in the brain. In Alzheimer's disease, the hippocampus is one of the first regions of the brain to suffer damage, short-term memory loss and disorientation are included among the early symptoms.  Hippocampal damage can also cause amnesia and an inability to form new memories, specifically those regarding time and location.

In a condition like Alzheimers disease,first, lesions occurs in the poorly myelinated limbic neurons in system areas related to memory and learning, such as the hippocampus and the association cortex,  Highly myelinated neurons are only affected in the final phases of the disease, since these neurological changes first occur in hippocampal area and than slowly spreads to other areas like, temporal, parietal, and finally frontal association cortices.long term memory is affected only on later stages of disease.