Brief Answer:
Possible causes; with recommendation for a complete medical checkup

Detailed Answer:
Hello ma'am and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. After reading your query I have a few things in my mind:

+Menopause: I am sure you are already post-menopausal; in most peri- or post-menopausal women the symptoms of menopause cause various changes in lifestyle and limitations (e.g. exhaustion, lethargy, memory loss, thinning of hair, hot flashes, etc.)
+Nutritional deficiencies: Can also be menopause related (E.g. vitamin D or calcium deficiency, brought on by menopause), or individual deficiencies like vitamin B12, etc.
+Anemia: Common in women
+Atrophy of the brain: Will require an MRI of your head/brain

I do not see any serious cause, and in majority of cases it is related to some deficiency, and so an elaborate medical checkup will be in order. Please do not hesitate to go about this, as it is best to find any abnormality as early as possible which can even make the most serious condition easy to treat (i.e. in the early stages).

I hope you find my response helpful. Please do not hesitate to write back to me for any further clarifications, I am always here to help.

Best wishes.

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