Re: Forgetting - Senility

Jeffrey Taylor

We should also be aware that a side effect of some drugs is memory loss.  

On Tuesday, October 26, 2021, 12:44:04 PM EDT, Herbert Lewis <herbertlewis@...> wrote:

Small writes "'senility' being a medical term meaning 'later life,' somewhat arbitrarily defined as beginning in our mid-sixties." (p. 188).  As Dave posted there are a wide range of diseases which correlate with old age and memory loss.  Particularly noteworthy is Alzheimer's disease which is a pathological condition that destroys hippocampus neurons which impacts the abilities first to form new memories, second to eventually access all memories, and finally to destroy enough brain cells to kill the afflicted.  I have often read and/or heard that Alzheimer's disease is likely universal, so prevalent that should people not die of something else first eventually everyone would die of this disease.  Small claims this is not true.

There are a number of physical attributes which deteriorate with age.  Bones become less dense.  Muscle mass diminishes.  Vertebrae changes cause the head to tip forward which constricts the throat more easily resulting in choking while eating.  Joint cartridge thins promoting injuries.  Ligaments become less elastic causing loss of flexibility.  Deterioration of eye lenses impact vision.  Ear presbycusis causes hearing loss.  The abilities to taste and smell diminishes.  Skin becomes thinner, less elastic, drier, and finely wrinkled.  Nerves conduct signals more slowly and repair themselves incompletely causing decreased sensation and strength.

Brains are not immune to these non-pathological deteriorations.  Neuron loss decreases sensitivity to chemical substances transmitting messages.  Blood flow to the brain decreases partially contributing to loss of mental functions such as vocabulary, the ability to learn new material, ability to recall words and names, etc.  This non-pathological condition, typically known as "senile dementia," is, like Alzheimer's disease, a progressive cognitive demise afflicting older people.

Small describes the use of Functional MRI to scan the hippocampus of many patients to ascertain whether Alzheimer's disease and normal aging have the same impact on hippocampus health.  Interestingly they do not.  The area of the hippocampus affected by Alzheimer's disease is the Entorhinal Cortex, that affected by normal aging is the Dentate Gyrus.  These are two distinct areas located at opposite ends of the hippocampus.  What I found absolutely amazing is that being afflicted with one of these maladies apparently protects against experiencing the other.  That is, the fMRI scans indicated that hippocampi with Alzheimer's disease show no sign of deterioration from cognitive aging and vice versa.  IMO that's astounding!

As an aside, if Carol C. reads this I'd be interested in her opinion.  She posted that she set a challenge for herself to memorize poetry.  My question is:  Is it more difficult now to memorize than it used to be?

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