Hello. I believe I can be of help to you with this issue.
Your wife may be experiencing what is called a fluent or receptive aphasia. This can be caused by small strokes
in language processing areas of the brain. In aphasia, no loss of general intelligence occurs, as is the case with dementia
or a progressive disease process, such as Alzheimer
's. If she had a stroke it was a small, localized one. You might want to check to see if her reading comprehension and expression are intact e.g., have her read a newspaper article and tell you what it means. There are often both hearing and reading comprehension problems with receptive aphasia, but not always.
Please make an appointment to see a clinical neuropsychologist and request a complete neuropsychological testing/evaluation. They can administer an exhaustive series of cognitive tests and quite finely pinpoint what happened, if a stroke or other neurological condition occurred. Alternatively, you can visit a neurologist, who can give you a variety of diagnostic possibilities, but won't give you the detailed 'summary' of where your wife functions in all cognitive domains compared to women her same age (memory, visual-motor functioning, information processing), as a neuropsychologist can.
I hope this information is helpful to you. Please let me know if I have overlooked any aspect of your original question. You can Google the topic: Receptive Aphasia and read more about it. Please hit the green Accept button at the bottom of the screen as well. Thanks.